AD9253BCPZRL7-105_技术文档

Quad, 14-Bit, 80 MSPS/105 MSPS/125 MSPS

Serial LVDS 1.8 V Analog-to-Digital Converter

Data Sheet

AD9253

FEATURES

FUNCTIONAL BLOCK DIAGRAM

AVDD

PDWN

DRVDD

1.8 V supply operation

14

Low power: 110 mW per channel at 125 MSPS with scalable

power options

SNR = 74 dB (to Nyquist)

D0+A

D0–A

SERIAL

LVDS

VIN+A

VIN–A

DIGITAL

PIPELINE

ADC

SERIALIZER

D1+A

D1–A

SERIAL

LVDS

14

VIN+B

DIGITAL

SERIALIZER

PIPELINE

ADC

D0+B

D0–B

SERIAL

LVDS

SFDR = 90 dBc (to Nyquist)

VIN–B

RBIAS

VREF

DNL = 0.75 LSB (typical); INL = 2.0 LSB (typical)

Serial LVDS (ANSI-644, default) and low power, reduced

signal option (similar to IEEE 1596.3)

650 MHz full power analog bandwidth

2 V p-p input voltage range

Serial port control

Full chip and individual channel power-down modes

Flexible bit orientation

Built-in and custom digital test pattern generation

Multichip sync and clock divider

Programmable output clock and data alignment

Programmable output resolution

Standby mode

SERIAL

LVDS

D1+B

D1–B

SENSE

FCO+

FCO–

D0+C

D0–C

D1+C

D1–C

1V

AD9253

REF

SELECT

SERIAL

LVDS

AGND

14

VIN+C

VIN–C

DIGITAL

SERIALIZER

PIPELINE

ADC

SERIAL

LVDS

D0+D

D0–D

SERIAL

LVDS

VIN+D

VIN–D

DIGITAL

SERIALIZER

PIPELINE

ADC

D1+D

D1–D

DCO+

DCO–

SERIAL

LVDS

SERIAL PORT

INTERFACE

CLOCK

MANAGEMENT

VCM

APPLICATIONS

Figure 1.

Medical ultrasound

High speed imaging

Quadrature radio receivers

Diversity radio receivers

Test equipment

as programmable output clock and data alignment and digital

test pattern generation. The available digital test patterns

include built-in deterministic and pseudorandom patterns, along

with custom user-defined test patterns entered via the serial port

interface (SPI).

GENERAL DESCRIPTION

The AD9253 is a quad, 14-bit, 80 MSPS/105 MSPS/125 MSPS

analog-to-digital converter (ADC) with an on-chip sample-

and-hold circuit designed for low cost, low power, small size,

and ease of use. The product operates at a conversion rate of

up to 125 MSPS and is optimized for outstanding dynamic

performance and low power in applications where a small

package size is critical.

The AD9253 is available in a RoHS-compliant, 48-lead LFCSP.

It is specified over the industrial temperature range of −40°C to

+85°C. This product is protected by a U.S. patent.

PRODUCT HIGHLIGHTS

1. Small Footprint. Four ADCs are contained in a small, space-

saving package.

2. Low power of 110 mW/channel at 125 MSPS with scalable

power options.

3. Pin compatible to the AD9633 12-bit quad ADC.

4. Ease of Use. A data clock output (DCO) operates at

frequencies of up to 500 MHz and supports double data

rate (DDR) operation.

The ADC requires a single 1.8 V power supply and LVPECL-/

CMOS-/LVDS-compatible sample rate clock for full performance

operation. No external reference or driver components are

required for many applications.

The ADC automatically multiplies the sample rate clock for the

appropriate LVDS serial data rate. A data clock output (DCO) for

capturing data on the output and a frame clock output (FCO)

for signaling a new output byte are provided. Individual-channel

power-down is supported and typically consumes less than 2 mW

when all channels are disabled. The ADC contains several features

designed to maximize flexibility and minimize system cost, such

5. User Flexibility. The SPI control offers a wide range of

flexible features to meet specific system requirements.

Rev. 0

Information furnished by Analog Devices is believed to be accurate and reliable. However, no

responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other

rights of third parties that may result from its use. Specifications subject to change without notice. No

license is granted by implication or otherwise under any patent or patent rights of Analog Devices.

Trademarks and registeredtrademarks arethe property of their respective owners.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: 781.329.4700

Fax: 781.461.3113

www.analog.com

AD9253

Data Sheet

TABLE OF CONTENTS

Features .............................................................................................. 1

Clock Input Considerations...................................................... 24

Power Dissipation and Power-Down Mode ........................... 26

Digital Outputs and Timing ..................................................... 27

Output Test Modes..................................................................... 30

Serial Port Interface (SPI).............................................................. 31

Configuration Using the SPI..................................................... 31

Hardware Interface..................................................................... 32

Configuration Without the SPI ................................................ 32

SPI Accessible Features.............................................................. 32

Memory Map .................................................................................. 33

Reading the Memory Map Register Table............................... 33

Memory Map Register Table..................................................... 34

Memory Map Register Descriptions........................................ 37

Applications Information.............................................................. 39

Design Guidelines ...................................................................... 39

Power and Ground Recommendations................................... 39

Exposed Pad Thermal Heat Slug Recommendations............ 39

VCM............................................................................................. 39

Reference Decoupling................................................................ 39

SPI Port........................................................................................ 39

Crosstalk Performance .............................................................. 39

Outline Dimensions....................................................................... 40

Ordering Guide .......................................................................... 40

Applications....................................................................................... 1

General Description......................................................................... 1

Functional Block Diagram .............................................................. 1

Product Highlights ........................................................................... 1

Revision History ............................................................................... 2

Specifications..................................................................................... 3

DC Specifications ......................................................................... 3

AC Specifications.......................................................................... 4

Digital Specifications ................................................................... 5

Switching Specifications .............................................................. 6

Timing Specifications .................................................................. 6

Absolute Maximum Ratings.......................................................... 11

Thermal Resistance .................................................................... 11

ESD Caution................................................................................ 11

Pin Configuration and Function Descriptions........................... 12

Typical Performance Characteristics ........................................... 14

AD9253-80 .................................................................................. 14

AD9253-105................................................................................ 16

AD9253-125................................................................................ 18

Equivalent Circuits......................................................................... 21

Theory of Operation ...................................................................... 22

Analog Input Considerations.................................................... 22

Voltage Reference ....................................................................... 23

REVISION HISTORY

10/11—Revision 0: Initial Version

Rev. 0 | Page 2 of 40

Data Sheet

AD9253

SPECIFICATIONS

DC SPECIFICATIONS

AVDD = 1.8 V, DRVDD = 1.8 V, 2 V p-p differential input, 1.0 V internal reference, AIN = −1.0 dBFS, unless otherwise noted.

Table 1.

AD9253-80

Min Typ Max Min Typ

14 14

AD9253-105

AD9253-125

Parameter¹

Temp

Max Min Typ

Max Unit

RESOLUTION

14

Bits

ACCURACY

No Missing Codes

Offset Error

Offset Matching

Gain Error

Gain Matching

Differential Nonlinearity (DNL)

Full

25°C

Full

25°C

Guaranteed

−0.7 −0.3 +0.1 −0.7 −0.3

−0.6 +0.2 +0.6 −0.6 +0.2

Guaranteed

+0.1 −0.7 −0.3

+0.6 −0.6 +0.2

+0.1 % FSR

+0.6 % FSR

−10 −5

0

−10 −5

1

0

1.6

−10 −5

1.1

0

1.6

% FSR

1

1.6

−1

+1.6 −0.8

+1.5 −0.8

+1.5 LSB

LSB

+4.0 LSB

LSB

0.8

0.75

2.0

2

0.75

2.0

2

Integral Nonlinearity (INL)

−4.0

+4.0 −4.0

4.0 −4.0

1.5

2

TEMPERATURE DRIFT

Offset Error

Full

ppm/°C

INTERNAL VOLTAGE REFERENCE

Output Voltage (1 V Mode)

Load Regulation at 1.0 mA (V_REF= 1 V)

Input Resistance

Full

0.98 1.0

1.02 0.98 1.0

1.02

V

mV

kΩ

2

7.5

2

7.5

2

7.5

INPUT-REFERRED NOISE

V_REF= 1.0 V

25°C

0.94

LSB rms

ANALOG INPUTS

Differential Input Voltage (V_REF= 1 V)

Common-Mode Voltage

Differential Input Resistance

Differential Input Capacitance

POWER SUPPLY

Full

2

V p-p

V

kΩ

pF

0.9

5.2

3.5

0.9

5.2

3.5

0.9

5.2

3.5

Full

AVDD

Full

25°C

1.7

1.8

131 144

63

42

1.9

1.7

1.8

158

67

1.9

172

95

1.7

1.8

183

71

1.9

200

100

V

mA

DRVDD

2

I_AVDD

I_DRVDD(ANSI-644 Mode)²

I_DRVDD(Reduced Range Mode)²

TOTAL POWER CONSUMPTION

DC Input

81

48

53

Full

326

349 405

375

405

423

457

mW

Sine Wave Input (Four Channels Including

Output Drivers ANSI-644 Mode)

481

540

Sine Wave Input (Four Channels Including

Output Drivers Reduced Range Mode)

25°C

311

371

425

mW

Power-Down

Standby³

Full

2

178

2

209

2

236

mW

¹See the AN-835 Application Note, Understanding High Speed ADC Testing and Evaluation, for definitions and for details on how these tests were completed.

²Measured with a low input frequency, full-scale sine wave on all four channels.

³Can be controlled via the SPI.

Rev. 0 | Page 3 of 40

AD9253

Data Sheet

AC SPECIFICATIONS

AVDD = 1.8 V, DRVDD = 1.8 V, 2 V p-p differential input, 1.0 V internal reference, AIN = −1.0 dBFS, unless otherwise noted.

Table 2.

AD9253-80

AD9253-105

AD9253-125

Parameter¹

Temp

Unit

Min Typ Max Min Typ Max Min Typ

Max

SIGNAL-TO-NOISE RATIO (SNR)

f_IN= 9.7 MHz

f_IN= 30.5 MHz

f_IN= 70 MHz

f_IN= 140 MHz

25°C

Full

25°C

75.4

74.9

72.2 74.7

72.3

75.1

75.0

72.2 74.4

73.1

75.3

75.2

74.2

72.2

70.7

dBFS

73

f_IN= 200 MHz

70.7

71.2

SIGNAL-TO-NOISE-AND-DISTORTION RATIO (SINAD)

f_IN= 9.7 MHz

f_IN= 30.5 MHz

f_IN= 70 MHz

f_IN= 140 MHz

25°C

Full

25°C

75.3

74.8

70.8 74.6

72.1

75.0

74.9

69.8 74.2

72.8

75.2

75.1

71.6 74.1

71.9

dBFS

f_IN= 200 MHz

70.5

70.8

70.4

EFFECTIVE NUMBER OF BITS (ENOB)

f_IN= 9.7 MHz

f_IN= 30.5 MHz

f_IN= 70 MHz

f_IN= 140 MHz

25°C

Full

25°C

12.2

12.1

11.9

11.6

11.5

12.1

12.0

11.8

11.5

12.2

12.1

12.0

11.6

11.4

Bits

f_IN= 200 MHz

SPURIOUS-FREE DYNAMIC RANGE (SFDR)

f_IN= 9.7 MHz

f_IN= 30.5 MHz

f_IN= 70 MHz

f_IN= 140 MHz

25°C

Full

25°C

98

93

94

85

84

98

92

89

85

82

98

92

90

85

83

dBc

77

75

77

f_IN= 200 MHz

WORST HARMONIC (SECOND OR THIRD)

f_IN= 9.7 MHz

f_IN= 30.5 MHz

f_IN= 70 MHz

f_IN= 140 MHz

25°C

Full

25°C

−98

−93

−94

−85

−84

−98

−92

−89 −75

−85

−82

−98

−92

−90

−85

−83

dBc

−77

−84

f_IN= 200 MHz

WORST OTHER HARMONIC (EXCLUDING SECOND OR THIRD)

f_IN= 9.7 MHz

f_IN= 30.5 MHz

f_IN= 70 MHz

f_IN= 140 MHz

25°C

Full

25°C

−100

−99

−98

−95

−99

−95 −77

−98

−92

−101

−100

−95

−96

−92

dBFS

f_IN= 200 MHz

TWO-TONE INTERMODULATION DISTORTION (IMD)—AIN1 AND

AIN2 = −7.0 dBFS

f_IN1= 70.5 MHz, f_IN2= 72.5 MHz

CROSSTALK²

CROSSTALK (OVERRANGE CONDITION)³

POWER SUPPLY REJECTION RATIO (PSRR)^{1, 4}

AVDD

25°C

Full

90

88

86

dBc

dB

−95

−89

−95

−89

−95

−89

25°C

dB

25°C

48

75

48

75

48

75

dB

DRVDD

ANALOG INPUT BANDWIDTH, FULL POWER

650

MHz

¹See the AN-835 Application Note, Understanding High Speed ADC Testing and Evaluation, for definitions and for details on how these tests were completed.

²Crosstalk is measured at 70 MHz with −1.0 dBFS analog input on one channel and no input on the adjacent channel.

³Overrange condition is specified with 3 dB of the full-scale input range.

⁴PSRR is measured by injecting a sinusoidal signal at 10 MHz to the power supply pin and measuring the output spur on the FFT. PSRR is calculated as the ratio of the

amplitudes of the spur voltage over the pin voltage, expressed in decibels.

Rev. 0 | Page 4 of 40

Data Sheet

AD9253

DIGITAL SPECIFICATIONS

AVDD = 1.8 V, DRVDD = 1.8 V, 2 V p-p differential input, 1.0 V internal reference, AIN = −1.0 dBFS, unless otherwise noted.

Table 3.

Parameter¹

Temp

Min

Typ

Max

Unit

CLOCK INPUTS (CLK+, CLK−)

Logic Compliance

CMOS/LVDS/LVPECL

Differential Input Voltage²

Input Voltage Range

Input Common-Mode Voltage

Input Resistance (Differential)

Input Capacitance

Full

25°C

0.2

AGND − 0.2

3.6

AVDD + 0.2

V p-p

V

kΩ

pF

0.9

15

4

LOGIC INPUTS (PDWN, SYNC, SCLK)

Logic 1 Voltage

Logic 0 Voltage

Full

1.2

0

AVDD + 0.2

0.8

V

Input Resistance

Input Capacitance

25°C

30

2

kΩ

pF

LOGIC INPUT (CSB)

Logic 1 Voltage

Logic 0 Voltage

Full

1.2

0

AVDD + 0.2

0.8

V

Input Resistance

Input Capacitance

25°C

26

2

kΩ

pF

LOGIC INPUT (SDIO)

Logic 1 Voltage

Logic 0 Voltage

Full

1.2

0

AVDD + 0.2

0.8

V

Input Resistance

Input Capacitance

25°C

26

5

kΩ

pF

LOGIC OUTPUT (SDIO)³

Logic 1 Voltage (I_OH= 800 μA)

Logic 0 Voltage (I_OL= 50 μA)

DIGITAL OUTPUTS (D0 x, D1 x), ANSI-644

Logic Compliance

Full

1.79

V

0.05

LVDS

Differential Output Voltage (V_OD)

Output Offset Voltage (V_OS)

Output Coding (Default)

Full

290

1.15

345

1.25

400

1.35

mV

V

Twos complement

DIGITAL OUTPUTS (D0 x, D1 x), LOW POWER,

REDUCED SIGNAL OPTION

Logic Compliance

LVDS

Differential Output Voltage (V_OD)

Output Offset Voltage (V_OS)

Output Coding (Default)

Full

160

1.15

200

1.25

230

1.35

mV

V

Twos complement

¹See the AN-835 Application Note, Understanding High Speed ADC Testing and Evaluation, for definitions and for details on how these tests were completed.

²This is specified for LVDS and LVPECL only.

³This is specified for 13 SDIO/OLM pins sharing the same connection.

Rev. 0 | Page 5 of 40

AD9253

Data Sheet

SWITCHING SPECIFICATIONS

AVDD = 1.8 V, DRVDD = 1.8 V, 2 V p-p differential input, 1.0 V internal reference, AIN = −1.0 dBFS, unless otherwise noted.

Table 4.

Parameter^{1, 2}

CLOCK³

Temp

Min

Typ

Max

Unit

Input Clock Rate

Conversion Rate

Full

10

1000

80/105/125

MHz

MSPS

ns

Clock Pulse Width High (t_EH)

Clock Pulse Width Low (t_EL)

OUTPUT PARAMETERS³

Propagation Delay (t_PD)

Rise Time (t_R) (20% to 80%)

Fall Time (t_F) (20% to 80%)

FCO Propagation Delay (t_FCO

DCO Propagation Delay (t_CPD

DCO to Data Delay (t_DATA

DCO to FCO Delay (t_FRAME

6.25/4.76/4.00

ns

Full

2.3

300

2.3

ns

ps

ns

ps

)

1.5

3.1

4

t_FCO+ (t_SAMPLE/16)

(t_SAMPLE/16)

4

)

(t_SAMPLE/16) − 300

(t_SAMPLE/16) + 300

4

)

Lane Delay (t_LD)

90

ps

Data to Data Skew (t_DATA-MAX− t_DATA-MIN

Wake-Up Time (Standby)

Wake-Up Time (Power-Down)⁵

Pipeline Latency

)

Full

50

200

ps

ns

μs

25°C

Full

250

375

16

Clock cycles

APERTURE

Aperture Delay (t_A)

Aperture Uncertainty (Jitter, t_J)

Out-of-Range Recovery Time

25°C

1

135

1

ns

fs rms

Clock cycles

¹See the AN-835 Application Note, Understanding High Speed ADC Testing and Evaluation, for definitions and for details on how these tests were completed.

²Measured on standard FR-4 material.

³Can be adjusted via the SPI. The conversion rate is the clock rate after the divider.

⁴t_SAMPLE/16 is based on the number of bits in two LVDS data lanes. t_SAMPLE= 1/f_S.

⁵Wake-up time is defined as the time required to return to normal operation from power-down mode.

TIMING SPECIFICATIONS

Table 5.

Unit

Parameter

Description

Limit

SYNC TIMING REQUIREMENTS

t_SSYNC

t_HSYNC

SYNC to rising edge of CLK+ setup time

SYNC to rising edge of CLK+ hold time

See Figure 74

0.24

0.40

ns typ

SPI TIMING REQUIREMENTS

t_DS

t_DH

t_CLK

t_S

t_H

t_HIGH

t_LOW

t_{EN_SDIO}

Setup time between the data and the rising edge of SCLK

Hold time between the data and the rising edge of SCLK

Period of the SCLK

Setup time between CSB and SCLK

Hold time between CSB and SCLK

SCLK pulse width high

SCLK pulse width low

Time required for the SDIO pin to switch from an input to an output relative to the

SCLK falling edge (not shown in Figure 74)

2

40

2

10

ns min

t_{DIS_SDIO}

Time required for the SDIO pin to switch from an output to an input relative to the

SCLK rising edge (not shown in Figure 74)

10

ns min

Rev. 0 | Page 6 of 40

Data Sheet

AD9253

Timing Diagrams

Refer to the Memory Map Register Descriptions section and Table 21 for SPI register settings.

N – 1

VIN±x

N

N + 1

t_A

t_EH

t_EL

CLK–

CLK+

DCO–

t_CPD

DDR

SDR

DCO+

DCO–

DCO+

FCO–

t_FCO

t_FRAME

FCO+

D0–A

t_PD

t_DATA

BITWISE

MODE

D12

D10

D08

D06

D04

D02

LSB

0

D12

D10

D08

D06

D04

D02

LSB

0

N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 16 N – 16 N – 16 N – 16 N – 16 N – 16 N – 16 N – 16

D0+A

D1–A

t_LD

MSB

D11

D09

D07

D05

D03

D01

0

MSB

D11

D09

D07

D05

D03

D01

0

N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 16 N – 16 N – 16 N – 16 N – 16 N – 16 N – 16 N – 16

D1+A

FCO–

FCO+

D0–A

BYTEWISE

MODE

D05

D04

D03

D02

D01

LSB

0

D05

D04

D03

D02

D01

LSB

0

N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 16 N – 16 N – 16 N – 16 N – 16 N – 16 N – 16 N – 16

D0+A

D1–A

MSB

D12

D11

D10

D09

D08

D07

D06

MSB

D12

D11

D10

D09

D08

D07

D06

N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 16 N – 16 N – 16 N – 16 N – 16 N – 16 N – 16 N – 16

D1+A

Figure 2. 16-Bit DDR/SDR, Two-Lane, 1× Frame Mode (Default)

Rev. 0 | Page 7 of 40

AD9253

Data Sheet

N – 1

VIN±x

CLK–

N + 1

t_A

N

t_EH

t_EL

CLK+

DCO–

t_CPD

DDR

SDR

DCO+

DCO–

DCO+

FCO–

t_FRAME

t_FCO

FCO+

D0–A

t_DATA

t_PD

BITWISE

MODE

D10

D08

D06

D04

D02

LSB

D10

D08

D06

D04

D02

LSB

N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 16 N – 16 N – 16 N – 16 N – 16 N – 16

D0+A

D1–A

t_LD

MSB

D09

D07

D05

D03

D01

MSB

D09

D07

D05

D03

D01

N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 16 N – 16 N – 16 N – 16 N – 16 N – 16

D1+A

FCO–

FCO+

D0–A

BYTEWISE

MODE

D05

D04

D03

D02

D01

LSB

D05

D04

D03

D02

D01

LSB

N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 16 N – 16 N – 16 N – 16 N – 16 N – 16

D0+A

D1–A

MSB

D10

D09

D08

D07

D06

MSB

D10

D09

D08

D07

D06

N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 16 N – 16 N – 16 N – 16 N – 16 N – 16

D1+A

N – 1

Figure 3. 12-Bit DDR/SDR, Two-Lane, 1× Frame Mode

VIN±x

N

N + 1

t_A

t_EH

t_EL

CLK–

CLK+

DCO–

t_CPD

DDR

SDR

DCO+

DCO–

DCO+

FCO–

t_FCO

t_FRAME

FCO+

D0–A

t_PD

t_DATA

BITWISE

MODE

D12

D10

D08

D06

D04

D02

LSB

0

D12

D10

D08

D06

D04

D02

LSB

0

N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 16 N – 16 N – 16 N – 16 N – 16 N – 16 N – 16 N – 16

D0+A

D1–A

t_LD

MSB

D11

D09

D07

D05

D03

D01

0

MSB

D11

D09

D07

D05

D03

D01

0

N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 16 N – 16 N – 16 N – 16 N – 16 N – 16 N – 16 N – 16

D1+A

FCO–

FCO+

D0–A

BYTEWISE

MODE

D05

D04

D03

D02

D01

LSB

0

D05

D04

D03

D02

D01

LSB

0

N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 16 N – 16 N – 16 N – 16 N – 16 N – 16 N – 16 N – 16

D0+A

D1–A

MSB

D12

D11

D10

D09

D08

D07

D06

MSB

D12

D11

D10

D09

D08

D07

D06

N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 16 N – 16 N – 16 N – 16 N – 16 N – 16 N – 16 N – 16

D1+A

Figure 4. 16-Bit DDR/SDR, Two-Lane, 2× Frame Mode

Rev. 0 | Page 8 of 40

Data Sheet

AD9253

N – 1

VIN±x

CLK–

N + 1

t_A

N

t_EH

t_EL

CLK+

DCO–

t_CPD

DDR

SDR

DCO+

DCO–

DCO+

FCO–

t_FRAME

t_FCO

FCO+

D0–A

t_DATA

t_PD

BITWISE

MODE

D10

D08

D06

D04

D02

LSB

D10

D08

D06

D04

D02

LSB

N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 16 N – 16 N – 16 N – 16 N – 16 N – 16

D0+A

D1–A

t_LD

MSB

D09

D07

D05

D03

D01

MSB

D09

D07

D05

D03

D01

N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 16 N – 16 N – 16 N – 16 N – 16 N – 16

D1+A

FCO–

FCO+

D0–A

BYTEWISE

MODE

D05

D04

D03

D02

D01

LSB

D05

D04

D03

D02

D01

LSB

N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 16 N – 16 N – 16 N – 16 N – 16 N – 16

D0+A

D1–A

MSB

D10

D09

D08

D07

D06

MSB

D10

D09

D08

D07

D06

N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 16 N – 16 N – 16 N – 16 N – 16 N – 16

D1+A

Figure 5. 12-Bit DDR/SDR, Two-Lane, 2× Frame Mode

N – 1

VIN±x

t_A

N

t_EH

t_EL

CLK–

CLK+

t_CPD

DCO–

DCO+

t_FCO

t_FRAME

FCO–

FCO+

t_DATA

t_PD

D0–x

D0+x

MSB

D12

D11

D10

D9

D8

D7

D6

D5

D4

D3

D2

D1

LSB

0

MSB

D14

D13

N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 16 N – 16 N – 16

Figure 6. Wordwise DDR, One-Lane, 1× Frame, 16-Bit Output Mode

Rev. 0 | Page 9 of 40

AD9253

Data Sheet

N – 1

VIN±x

t_A

N

t_EH

t_EL

CLK–

CLK+

t_CPD

DCO–

DCO+

t_FCO

t_FRAME

FCO–

FCO+

t_DATA

t_PD

D0–x

D0+x

MSB

D10

D9

D8

D7

D6

D5

D4

D3

D2

D1

D0

MSB

D10

N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 16 N – 16

Figure 7. Wordwise DDR, One-Lane, 1× Frame, 12-Bit Output Mode

CLK+

t_SSYNC

t_HSYNC

SYNC

Figure 8. SYNC Input Timing Requirements

Rev. 0 | Page 10 of 40

Data Sheet

AD9253

ABSOLUTE MAXIMUM RATINGS

THERMAL RESISTANCE

Table 6.

Parameter

Rating

Table 7. Thermal Resistance

Electrical

Air Flow

Velocity

(m/sec)

AVDD to AGND

DRVDD to AGND

Digital Outputs

(D0 x, D1 x, DCO+,

DCO−, FCO+, FCO−) to AGND

−0.3 V to +2.0 V

1

Package Type

θ_JA

θ_JB

θ_JC

7.1

Unit

48-Lead LFCSP

0.0

23.7

20.0

18.7

7.8

N/A

°C/W

7 mm × 7 mm 1.0

(CP-48-13) 2.5

N/A °C/W

CLK+, CLK− to AGND

−0.3 V to +2.0 V

¹θ_JAfor a 4-layer PCB with solid ground plane (simulated). Exposed pad

soldered to PCB.

VIN+x, VIN−x to AGND

SCLK/DTP, SDIO/OLM, CSB to AGND

SYNC, PDWN to AGND

RBIAS to AGND

VREF, SENSE to AGND

Environmental

ESD CAUTION

Operating Temperature

Range (Ambient)

Maximum Junction

Temperature

−40°C to +85°C

150°C

Lead Temperature

(Soldering, 10 sec)

300°C

Storage Temperature

Range (Ambient)

−65°C to +150°C

Stresses above those listed under Absolute Maximum Ratings

may cause permanent damage to the device. This is a stress

rating only; functional operation of the device at these or any

other conditions above those indicated in the operational

section of this specification is not implied. Exposure to absolute

maximum rating conditions for extended periods may affect

device reliability.

Rev. 0 | Page 11 of 40

AD9253

Data Sheet

PIN CONFIGURATION AND FUNCTION DESCRIPTIONS

1

2

3

4

5

6

7

8

9

36 VIN+A

VIN+D

VIN–D

AVDD

CLK–

CLK+

AVDD

DRVDD

D1–D

35

34

VIN–A

AVDD

33 PDWN

32

31

CSB

SDIO/OLM

AD9253

TOP VIEW

(Not to Scale)

30 SCLK/DTP

DRVDD

29

28 D0+A

10

D0–A

D1+D

27

11

D1+A

D0–D

26

D0+D 12

25 D1–A

NOTES

1. THE EXPOSED THERMAL PAD ON THE BOTTOM OF THE

PACKAGE PROVIDES THE ANALOG GROUND FOR THE PART.

THIS EXPOSED PAD MUST BE CONNECTED TO GROUND FOR

PROPER OPERATION.

Figure 9. 48-Lead LFCSP Pin Configuration, Top View

Table 8. Pin Function Descriptions

Pin No.

Mnemonic

Description

0

AGND,

Exposed Pad

Analog Ground, Exposed Pad. The exposed thermal pad on the bottom of the package provides the

analog ground for the part. This exposed pad must be connected to ground for proper operation.

1

2

VIN+D

VIN−D

ADC D Analog Input True.

ADC D Analog Input Complement.

1.8 V Analog Supply Pins.

3, 4, 7, 34, 39, 45, 46 AVDD

5, 6

CLK−, CLK+

DRVDD

Differential Encode Clock. PECL, LVDS, or 1.8 V CMOS inputs.

Digital Output Driver Supply.

Channel D Digital Outputs.

Channel C Digital Outputs.

Data Clock Outputs.

Frame Clock Outputs.

Channel B Digital Outputs.

Channel A Digital Outputs.

SPI Clock Input/Digital Test Pattern.

SPI Data Input and Output Bidirectional SPI Data/Output Lane Mode.

SPI Chip Select Bar. Active low enable; 30 kΩ internal pull-up.

8, 29

9, 10

11, 12

13, 14

15, 16

17, 18

19, 20

21, 22

23, 24

25, 26

27, 28

30

D1−D, D1+D

D0−D, D0+D

D1−C, D1+C

D0−C, D0+C

DCO−, DCO+

FCO−, FCO+

D1−B, D1+B

D0−B, D0+B

D1−A, D1+A

D0−A, D0+A

SCLK/DTP

31

32

SDIO/OLM

CSB

33

PDWN

Digital Input, 30 kΩ Internal Pull-Down.

PDWN high = power-down device.

PDWN low = run device, normal operation.

35

36

37

38

40

41

42

43

VIN−A

VIN+A

VIN+B

VIN−B

RBIAS

SENSE

VREF

ADC A Analog Input Complement.

ADC A Analog Input True.

ADC B Analog Input True.

ADC B Analog Input Complement.

Sets Analog Current Bias. Connect to 10 kΩ (1% tolerance) resistor to ground.

Reference Mode Selection.

Voltage Reference Input and Output.

Analog Input Common-Mode Voltage.

VCM

Rev. 0 | Page 12 of 40

Data Sheet

AD9253

Pin No.

44

47

Mnemonic

SYNC

VIN−C

Description

Digital Input. SYNC input to clock divider.

ADC C Analog Input Complement.

ADC C Analog Input True.

48

VIN+C

Rev. 0 | Page 13 of 40

AD9253

Data Sheet

TYPICAL PERFORMANCE CHARACTERISTICS

AD9253-80

0

–20

AIN = –1dBFS

SNR = 75.5dB

ENOB = 12.07BITS

AIN = –1 DBFS

SNR = 72.3dB

–20

ENOB = 11.5 BITS

SFDR = 85dBc

SFDR = 99.3dBc

–40

–60

–80

–60

–80

–100

–120

–140

–100

–120

–140

0

5

10

15

20

25

30

35

40

0

5

10

15

20

25

30

35

40

FREQUENCY (MHz)

Figure 10. Single-Tone 16k FFT with f_IN= 9.7 MHz, f_SAMPLE= 80 MSPS

Figure 13. Single-Tone 16k FFT with f_IN= 140 MHz, f_SAMPLE= 80 MSPS

0

AIN = –1dBFS

SNR = 73.9dB

ENOB = 11.9 BITS

AIN = –1dBFS

SNR = 70.7dB

ENOB = 11.3 BITS

–20

SFDR = 92.7dBc

SFDR = 83.7dBc

–40

–60

–80

–60

–80

–100

–120

–140

–100

–120

–140

0

5

10

15

20

25

30

35

40

0

5

10

15

20

25

30

35

40

FREQUENCY (MHz)

Figure 11. Single-Tone 16k FFT with f_IN= 30.5 MHZ, f_SAMPLE= 80 MSPS

Figure 14. Single-Tone 16k FFT with f_IN= 200 MHz, f_SAMPLE= 80 MSPS

0

120

AIN = –1dBFS

SNR = 74.7dB

ENOB = 11.9 BITS

SFDRFS

–20

100

SFDR = 94.2dBc

SNRFS

–40

80

–60

–80

60

SFDR

40

SNR

–100

–120

–140

20

0

–20

0

5

10

15

20

25

30

35

40

–100 –90 –80 –70 –60 –50 –40 –30 –20 –10

0

FREQUENCY (MHz)

INPUT AMPLITUDE (dBFS)

Figure 12. Single-Tone 16k FFT with f_IN= 70 MHz, f_SAMPLE= 80 MSPS

Figure 15. SNR/SFDR vs. Analog Input Level, f_IN= 9.7 MHz, f_SAMPLE= 80 MSPS

Rev. 0 | Page 14 of 40

Data Sheet

AD9253

0

100

90

80

70

60

50

40

30

20

10

0

AIN1 AND AIN2 = –7dBFS

SFDR = 90.9dBc

IMD2 = 91dBc

SFDR (dBc)

SNR (dBFS)

–20

IMD3 = 90.9dBc

–40

–60

–80

–100

–120

–140

0

5

10

15

20

25

30

35

40

0

20

40

60

80

100 120 140 160 180 200

FREQUENCY (MHz)

INPUT FREQUENCY (MHz)

Figure 16. Two-Tone 16k FFT with f_IN1= 70.5 MHz and f_IN2= 72.5 MHz,

_SAMPLE= 80 MSPS

Figure 18. SNR/SFDR vs. f_IN, f_SAMPLE= 80 MSPS

f

0

105

100

95

SFDR (dBc)

–20

SFDR (dBc)

–40

–60

IMD3 (dBc)

90

85

–80

80

SFDR (dBFS)

SNR (dBFS)

–100

–120

75

IMD3 (dBFS)

70

–40

–90

–78

–66

–54

–42

–30

–18

–6

–15

10

35

60

85

INPUT AMPLITUDE (dBFS)

TEMPERATURE (°C)

Figure 17. Two-Tone SFDR/IMD3 vs. Input Amplitude (AIN) with

f_IN1= 70.5 MHz and f_IN2= 72.5 MHz, f_SAMPLE= 80 MSPS

Figure 19. SNR/SFDR vs. Temperature, f_IN= 10.3 MHz, f_SAMPLE= 80 MSPS

Rev. 0 | Page 15 of 40

AD9253

Data Sheet

AD9253-105

0

–20

AIN = –1dBFS

SNR = 75.1dB

ENOB = 12.02 BITS

SFDR = 97.8dBc

AIN = –1dBFS

SNR = 73.1dB

ENOB = 11.6 BITS

SFDR = 85dBc

–20

–40

–60

–80

–100

–120

–100

–120

–140

0

10

20

30

40

50

0

10

20

30

40

50

FREQUENCY (MHz)

Figure 20. Single-Tone 16k FFT with f_IN= 9.7 MHz, f_SAMPLE= 105 MSPS

Figure 23. Single-Tone 16k FFT with f_IN= 140 MHz, f_SAMPLE= 105 MSPS

0

AIN = –1dBFS

SNR = 74dB

ENOB = 11.9 BITS

AIN = –1dBFS

SNR = 71.2dB

–20

ENOB = 11.3 BITS

SFDR = 82dBc

SFDR = 92.1dBc

–40

–60

–80

–60

–80

–100

–120

–140

–100

–120

–140

0

10

20

30

40

50

0

10

20

30

40

50

FREQUENCY (MHz)

Figure 21. Single-Tone 16k FFT with f_IN= 30.5 MHZ, f_SAMPLE= 105 MSPS

Figure 24. Single-Tone 16k FFT with f_IN= 200 MHz, f_SAMPLE= 105 MSPS

0

120

AIN = –1dBFS

SNR = 73.4dB

ENOB = 11.9 BITS

SFDRFS

–20

100

SFDR = 89.8dBc

–40

SNRFS

80

–60

–80

60

SFDR

40

SNR

–100

–120

–140

20

0

–20

0

10

20

30

40

50

–100 –90 –80 –70 –60 –50 –40 –30 –20 –10

0

FREQUENCY (MHz)

INPUT AMPLITUDE (dBFS)

Figure 22. Single-Tone 16k FFT with f_IN= 70 MHz, f_SAMPLE= 105 MSPS

Figure 25. SNR/SFDR vs. Analog Input Level, f_IN= 9.7 MHz, f_SAMPLE= 105 MSPS

Rev. 0 | Page 16 of 40

Data Sheet

AD9253

0

100

90

80

70

60

50

40

30

20

10

0

AIN1 AND AIN2 = –7dBFS

SFDR = 87.5dBc

IMD2 = 92.6dBc

IMD3 = 87.5dBc

SFDR (dBc)

SNR (dBFS)

–20

–40

–60

–80

–100

–120

–140

0

10

20

30

40

50

0

20

40

60

80

100 120 140 160 180 200

FREQUENCY (MHz)

INPUT FREQUENCY (MHz)

Figure 26. Two-Tone 16k FFT with f_IN1= 70.5 MHz and f_IN2= 72.5 MHz,

Figure 28. SNR/SFDR vs. f_IN, f_SAMPLE= 105 MSPS

f

_SAMPLE= 105 MSPS

0

100

95

90

85

80

75

70

SFDR (dBc)

–20

SFDR (dBc)

–40

–60

IMD3 (dBc)

–80

SNR (dBFS)

SFDR (dBFS)

–100

–120

IMD3 (dBFS)

–90

–78

–66

–54

–42

–30

–18

–6

–40

–15

10

35

60

85

INPUT AMPLITUDE (dBFS)

TEMPERATURE (°C)

Figure 27. Two-Tone SFDR/IMD3 vs. Input Amplitude (AIN) with

f_IN1= 70.5 MHz and f_IN2= 72.5 MHz, f_SAMPLE= 105 MSPS

Figure 29. SNR/SFDR vs. Temperature, f_IN= 10.3 MHz, f_SAMPLE= 105 MSPS

Rev. 0 | Page 17 of 40

AD9253

Data Sheet

AD9253-125

0

–20

AIN = –1dBFS

SNR = 75.3dB

ENOB = 12.04 BITS

SFDR = 98.52dBc

AIN = –1dBFS

SNR = 73.1dB

ENOB = 11.6 BITS

SFDR = 85dBc

–20

–40

–60

–80

–100

–120

–100

–120

–140

0

10

20

30

40

50

60

0

10

20

30

40

50

60

FREQUENCY (MHz)

Figure 30. Single-Tone 16k FFT with f_IN= 9.7 MHz, f_SAMPLE= 125 MSPS

Figure 33. Single-Tone 16k FFT with f_IN= 140 MHz, f_SAMPLE= 125 MSPS

0

AIN = –1dBFS

SNR = 70.6dB

ENOB = 11.2 BITS

AIN = –1dBFS

SNR = 74.2dB

ENOB = 12 BITS

–20

SFDR = 83.2dBc

SFDR = 92.5dBc

–40

–60

–80

–60

–80

–100

–120

–140

–100

–120

–140

0

10

20

30

40

50

60

0

10

20

30

40

50

60

FREQUENCY (MHz)

Figure 34. Single-Tone 16k FFT with f_IN= 200 MHz, f_SAMPLE= 125 MSPS

Figure 31. Single-Tone 16k FFT with f_IN= 30.5 MHZ, f_SAMPLE= 125 MSPS

0

A

= –1dBFS

IN

AIN = –1dBFS

SNR = 73.2dB

ENOB = 11.9 BITS

SNR = 72.4dB

ENOB = 11.7 BITS

SFDR = 88.4dBc

–20

–40

–20

SFDR = 91.2dBc

–40

–60

–80

–100

–120

–140

–100

–120

–140

0

10

20

30

40

50

60

0

10

20

30

40

50

60

FREQUENCY (MHz)

Figure 35. Single-Tone 16k FFT with f_IN= 140 MHz at f_SAMPLE= 122.88 MSPS

Figure 32. Single-Tone 16k FFT with f_IN= 70 MHz, f_SAMPLE= 125 MSPS

Rev. 0 | Page 18 of 40

Data Sheet

AD9253

120

100

90

80

70

60

50

40

30

20

10

0

SFDRFS

SNRFS

SFDR (dBc)

SNR (dBFS)

100

80

60

40

20

0

SFDR

SNR

–100 –90 –80 –70 –60 –50 –40 –30 –20 –10

0

20

40

60

80

100 120 140 160 180 200

INPUT AMPLITUDE (dBFS)

INPUT FREQUENCY (MHz)

Figure 36. SNR/SFDR vs. Analog Input Level, f_IN= 9.7 MHz, f_SAMPLE= 125 MSPS

Figure 39. SNR/SFDR vs. f_IN, f_SAMPLE= 125 MSPS

0

100

95

90

85

80

75

70

SFDR (dBc)

AIN1 AND AIN2 = –7dBFS

SFDR = 86.2dBc

IMD2 = 98.3dBc

–20

IMD3 = 86.2dBc

–40

–60

–80

–100

–120

–140

SNR (dBFS)

0

10

20

30

40

50

60

–40

–15

10

35

60

85

FREQUENCY (MHz)

TEMPERATURE (°C)

Figure 37. Two-Tone 16k FFT with f_IN1= 70.5 MHz and f_IN2= 72.5 MHz,

Figure 40. SNR/SFDR vs. Temperature, f_IN= 10.3 MHz, f_SAMPLE= 125 MSPS

f

_SAMPLE= 125 MSPS

2.5

2.0

0

–20

1.5

SFDR (dBc)

1.0

–40

–60

0.5

IMD3 (dBc)

0

–0.5

–1.0

–1.5

–2.0

–2.5

–80

SFDR (dBFS)

–100

–120

IMD3 (dBFS)

0

2000

4000

6000

8000 10000 12000 14000 16000

–90

–78

–66

–54

–42

–30

–18

–6

OUTPUT CODE

INPUT AMPLITUDE (dBFS)

Figure 41. INL, f_IN= 9.7 MHz, f_SAMPLE= 125 MSPS

Figure 38. Two-Tone SFDR/IMD3 vs. Input Amplitude (AIN) with

f_IN1= 70.5 MHz and f_IN2= 72.5 MHz, f_SAMPLE= 125 MSPS

Rev. 0 | Page 19 of 40

AD9253

Data Sheet

1.0

0.8

105

100

95

SFDR

0.6

0.4

90

0.2

85

0

–0.2

–0.4

–0.6

–0.8

80

SNRFS

75

70

65

20

–1.0

0

45

70

95

120

2000

4000

6000

8000 10000 12000 14000 16000

SAMPLE FREQUENCY (MSPS)

OUTPUT CODE

Figure 45. SNR/SFDR vs. Encode, f_IN= 9.7 MHz, f_SAMPLE= 125 MSPS

Figure 42. DNL, f_IN= 9.7 MHz, f_SAMPLE= 125 MSPS

500,000

450,000

105

100

0.94 LSB rms

400,000

350,000

95

SFDR

90

85

80

300,000

250,000

200,000

150,000

100,000

50,000

SNRFS

75

70

0

65

N – 3

N – 4

N – 2 N – 1

N

N + 1 N + 2 N + 3 N + 4 N + 5

20

45

70

95

120

CODE

SAMPLE FREQUENCY (MSPS)

Figure 46. SNR/SFDR vs. Encode, f_IN= 70 MHz, f_SAMPLE= 125 MSPS

Figure 43. Input-Referred Noise Histogram, f_SAMPLE= 125 MSPS

100

90

80

70

60

50

40

30

20

10

0

DRVDD

AVDD

1

10

FREQUENCY (MHz)

Figure 44. PSRR vs. Frequency, f_CLK= 125 MHz, f_SAMPLE= 125 MSPS

Rev. 0 | Page 20 of 40

Data Sheet

AD9253

EQUIVALENT CIRCUITS

AVDD

350Ω

SCLK/DTP, SYNC,

AND PDWN

VIN±x

30kΩ

Figure 47. Equivalent Analog Input Circuit

Figure 51. Equivalent SCLK/DTP, SYNC, and PDWN Input Circuit

AVDD

5Ω

CLK+

AVDD

15kΩ

0.9V

AVDD

375Ω

RBIAS

AND VCM

5Ω

CLK–

Figure 52. Equivalent RBIAS and VCM Circuit

Figure 48. Equivalent Clock Input Circuit

AVDD

30kΩ

350Ω

SDIO/OLM

30kΩ

350Ω

30kΩ

CSB

Figure 53. Equivalent CSB Input Circuit

Figure 49. Equivalent SDIO/OLM Input Circuit

DRVDD

AVDD

V

D0–x, D1–x

D0+x, D1+x

V

375Ω

VREF

7.5kΩ

DRGND

Figure 50. Equivalent Digital Output Circuit

Figure 54. Equivalent VREF Circuit

Rev. 0 | Page 21 of 40

AD9253

Data Sheet

THEORY OF OPERATION

the output stage of the driving source. In addition, low Q inductors

or ferrite beads can be placed on each leg of the input to reduce

high differential capacitance at the analog inputs and therefore

achieve the maximum bandwidth of the ADC. Such use of low

Q inductors or ferrite beads is required when driving the converter

front end at high IF frequencies. Either a differential capacitor or

two single-ended capacitors can be placed on the inputs to

provide a matching passive network. This ultimately creates a

low-pass filter at the input to limit unwanted broadband noise.

See the AN-742 Application Note, the AN-827 Application Note,

and the Analog Dialogue article “Transformer-Coupled Front-

End for Wideband A/D Converters” (Volume 39, April 2005) for

more information. In general, the precise values depend on the

application.

The AD9253 is a multistage, pipelined ADC. Each stage

provides sufficient overlap to correct for flash errors in the

preceding stage. The quantized outputs from each stage are

combined into a final 14-bit result in the digital correction

logic. The serializer transmits this converted data in a 16-bit

output. The pipelined architecture permits the first stage to

operate with a new input sample while the remaining stages

operate with preceding samples. Sampling occurs on the rising

edge of the clock.

Each stage of the pipeline, excluding the last, consists of a low

resolution flash ADC connected to a switched-capacitor DAC

and an interstage residue amplifier (for example, a multiplying

digital-to-analog converter (MDAC)). The residue amplifier

magnifies the difference between the reconstructed DAC output

and the flash input for the next stage in the pipeline. One bit of

redundancy is used in each stage to facilitate digital correction

of flash errors. The last stage simply consists of a flash ADC.

Input Common Mode

The analog inputs of the AD9253 are not internally dc-biased.

Therefore, in ac-coupled applications, the user must provide

this bias externally. Setting the device so that V_CM= AVDD/2 is

recommended for optimum performance, but the device can

function over a wider range with reasonable performance, as

shown in Figure 56.

The output staging block aligns the data, corrects errors, and

passes the data to the output buffers. The data is then serialized

and aligned to the frame and data clocks.

ANALOG INPUT CONSIDERATIONS

An on-chip, common-mode voltage reference is included in the

design and is available from the VCM pin. The VCM pin must

be decoupled to ground by a 0.1 μF capacitor, as described in

the Applications Information section.

The analog input to the AD9253 is a differential switched-

capacitor circuit designed for processing differential input

signals. This circuit can support a wide common-mode range

while maintaining excellent performance. By using an input

common-mode voltage of midsupply, users can minimize

signal-dependent errors and achieve optimum performance.

Maximum SNR performance is achieved by setting the ADC to

the largest span in a differential configuration. In the case of the

AD9253, the largest input span available is 2 V p-p.

100

SFDR

90

H

C_PAR

80

SNRFS

H

VIN+x

C_SAMPLE

70

60

50

40

30

20

S

C_SAMPLE

VIN–x

H

C_PAR

H

Figure 55. Switched-Capacitor Input Circuit

0.5

0.7

0.9

(V)

1.1

1.3

The clock signal alternately switches the input circuit between

sample mode and hold mode (see Figure 55). When the input

circuit is switched to sample mode, the signal source must be

capable of charging the sample capacitors and settling within

one-half of a clock cycle. A small resistor in series with each

input can help reduce the peak transient current injected from

V

CM

Figure 56. SNR/SFDR vs. Common-Mode Voltage,

f_IN= 9.7 MHz, f_SAMPLE= 125 MSPS

Rev. 0 | Page 22 of 40

Data Sheet

AD9253

Differential Input Configurations

Internal Reference Connection

There are several ways to drive the AD9253 either actively or

passively. However, optimum performance is achieved by driving

the analog inputs differentially. Using a differential double balun

configuration to drive the AD9253 provides excellent performance

and a flexible interface to the ADC (see Figure 58) for baseband

applications.

A comparator within the AD9253 detects the potential at the

SENSE pin and configures the reference into two possible

modes, which are summarized in Table 9. If SENSE is grounded,

the reference amplifier switch is connected to the internal resistor

divider (see Figure 57), setting VREF to 1.0 V.

Table 9. Reference Configuration Summary

For applications where SNR is a key parameter, differential trans-

former coupling is the recommended input configuration (see

Figure 59), because the noise performance of most amplifiers is

not adequate to achieve the true performance of the AD9253.

Resulting

Differential

Span (V p-p)

SENSE

Voltage (V) VREF (V)

Resulting

Selected Mode

Fixed Internal

Reference

AGND to

0.2

1.0 internal

2.0

Regardless of the configuration, the value of the shunt capacitor,

C, is dependent on the input frequency and may need to be

reduced or removed.

Fixed External

Reference

AVDD

1.0 applied

to external

VREF pin

2.0

It is not recommended to drive the AD9253 inputs single-ended.

VIN+A/VIN+B

VOLTAGE REFERENCE

VIN–A/VIN–B

A stable and accurate 1.0 V voltage reference is built into the

AD9253. VREF can be configured using either the internal 1.0 V

reference or an externally applied 1.0 V reference voltage. The

various reference modes are summarized in the Internal Reference

Connection section and the External Reference Operation

section. The VREF pin should be externally decoupled to

ground with a low ESR, 1.0 ꢀF capacitor in parallel with a low

ESR, 0.1 ꢀF ceramic capacitor.

ADC

CORE

VREF

0.1µF

1.0µF

SELECT

LOGIC

SENSE

0.5V

ADC

Figure 57. Internal Reference Configuration

0.1µF

R

*C1

5pF

0.1µF

VIN+x

33Ω

C

2V p-p

C

ADC

0.1µF

C

R

VCM

VIN–x

33Ω

ET1-1-I3

*C1

R

200Ω

*C1 IS OPTIONAL

0.1µF

C

0.1µF

Figure 58. Differential Double Balun Input Configuration for Baseband Applications

ADT1-1WT

1:1 Z RATIO

*C1

R

VIN+x

VIN–x

33ꢀ

2Vp-p

49.9ꢀ

ADC

C

5pF

*C1

R

VCM

33ꢀ

200ꢀ

0.1µF

0.1μF

*C1 IS OPTIONAL

Figure 59. Differential Transformer-Coupled Configuration

for Baseband Applications

Rev. 0 | Page 23 of 40

AD9253

Data Sheet

If the internal reference of the AD9253 is used to drive multiple

converters to improve gain matching, the loading of the reference

by the other converters must be considered. Figure 60 shows

how the internal reference voltage is affected by loading.

0

Clock Input Options

The AD9253 has a flexible clock input structure. The clock input

can be a CMOS, LVDS, LVPECL, or sine wave signal.

Regardless of the type of signal being used, clock source jitter is

of the most concern, as described in the Jitter Considerations

section.

–0.5

–1.0

Figure 62 and Figure 63 show two preferred methods for clock-

ing the AD9253 (at clock rates up to 1 GHz prior to internal CLK

divider). A low jitter clock source is converted from a single-

ended signal to a differential signal using either an RF transformer

or an RF balun.

INTERNAL V

REF

= 1V

–1.5

–2.0

–2.5

–3.0

–3.5

–4.0

–4.5

–5.0

The RF balun configuration is recommended for clock frequencies

between 125 MHz and 1 GHz, and the RF transformer is recom-

mended for clock frequencies from 10 MHz to 200 MHz. The

back-to-back Schottky diodes across the transformer/balun

secondary winding limit clock excursions into the AD9253 to

approximately 0.8 V p-p differential.

0

0.5

1.0

1.5

2.0

2.5

3.0

LOAD CURRENT (mA)

This limit helps prevent the large voltage swings of the clock

from feeding through to other portions of the AD9253 while

preserving the fast rise and fall times of the signal that are critical

to achieving low jitter performance. However, the diode

capacitance comes into play at frequencies above 500 MHz. Care

must be taken in choosing the appropriate signal limiting diode.

Figure 60. V_REFError vs. Load Current

External Reference Operation

The use of an external reference may be necessary to enhance

the gain accuracy of the ADC or improve thermal drift charac-

teristics. Figure 61 shows the typical drift characteristics of the

internal reference in 1.0 V mode.

®

4

Mini-Circuits

ADT1-1WT, 1:1 Z

0.1µF

XFMR

CLOCK

INPUT

2

0

CLK+

100ꢀ

50ꢀ

ADC

0.1µF

CLK–

SCHOTTKY

DIODES:

0.1µF

–2

–4

–6

–8

HSMS2822

Figure 62. Transformer-Coupled Differential Clock (Up to 200 MHz)

0.1µF

CLOCK

INPUT

CLK+

50ꢀ

ADC

–40

–15

10

35

60

85

0.1µF

CLK–

TEMPERATURE (°C)

SCHOTTKY

DIODES:

HSMS2822

Figure 61. Typical V_REFDrift

When the SENSE pin is tied to AVDD, the internal reference is

disabled, allowing the use of an external reference. An internal

reference buffer loads the external reference with an equivalent

7.5 kΩ load (see Figure 54). The internal buffer generates the

positive and negative full-scale references for the ADC core. There-

fore, the external reference must be limited to a maximum of 1.0 V.

Figure 63. Balun-Coupled Differential Clock (Up to 1 GHz)

If a low jitter clock source is not available, another option is to

ac couple a differential PECL signal to the sample clock input

pins, as shown in Figure 65. The AD9510/AD9511/AD9512/

AD9513/AD9514/AD9515/AD9516/AD9517 clock drivers offer

excellent jitter performance.

It is not recommended to leave the SENSE pin floating.

A third option is to ac couple a differential LVDS signal to the

sample clock input pins, as shown in Figure 66. The AD9510/

AD9511/AD9512/AD9513/AD9514/AD9515/AD9516/AD9517

clock drivers offer excellent jitter performance.

CLOCK INPUT CONSIDERATIONS

For optimum performance, clock the AD9253 sample clock

inputs, CLK+ and CLK−, with a differential signal. The signal

is typically ac-coupled into the CLK+ and CLK− pins via a

transformer or capacitors. These pins are biased internally

(see Figure 48) and require no external bias.

In some applications, it may be acceptable to drive the sample

clock inputs with a single-ended 1.8 V CMOS signal. In such

applications, drive the CLK+ pin directly from a CMOS gate, and

Rev. 0 | Page 24 of 40

Data Sheet

AD9253

80

75

70

65

60

bypass the CLK− pin to ground with a 0.1 ꢀF capacitor (see

Figure 67).

SNRFS (DCS ON)

SNRFS (DCS OFF)

Input Clock Divider

The AD9253 contains an input clock divider with the ability

to divide the input clock by integer values between 1 and 8.

The AD9253 clock divider can be synchronized using the

external SYNC input. Bit 0 and Bit 1 of Register 0x109 allow the

clock divider to be resynchronized on every SYNC signal or

only on the first SYNC signal after the register is written. A

valid SYNC causes the clock divider to reset to its initial state.

This synchronization feature allows multiple parts to have their

clock dividers aligned to guarantee simultaneous input sampling.

55

40

42

44

46

48

50

52

54

56

58

60

DUTY CYCLE (%)

Clock Duty Cycle

Figure 64. SNR vs. DCS On/Off

Typical high speed ADCs use both clock edges to generate a vari-

ety of internal timing signals and, as a result, may be sensitive to

clock duty cycle. Commonly, a 5% tolerance is required on the

clock duty cycle to maintain dynamic performance characteristics.

Jitter in the rising edge of the input is still of concern and is not

easily reduced by the internal stabilization circuit. The duty

cycle control loop does not function for clock rates less than

20 MHz, nominally. The loop has a time constant associated

with it that must be considered in applications in which the

clock rate can change dynamically. A wait time of 1.5 μs to 5 μs

is required after a dynamic clock frequency increase or decrease

before the DCS loop is relocked to the input signal.

The AD9253 contains a duty cycle stabilizer (DCS) that retimes

the nonsampling (falling) edge, providing an internal clock

signal with a nominal 50% duty cycle. This allows the user to

provide a wide range of clock input duty cycles without affecting

the performance of the AD9253. Noise and distortion perform-

ance are nearly flat for a wide range of duty cycles with the DCS

on, as shown in Figure 64.

0.1µF

CLK+

CLOCK

INPUT

AD951x

PECL DRIVER

100ꢀ

ADC

0.1µF

CLK–

CLOCK

INPUT

240ꢀ

50kꢀ

Figure 65. Differential PECL Sample Clock (Up to 1 GHz)

0.1µF

CLOCK

INPUT

CLK+

AD951x

LVDS DRIVER

100ꢀ

ADC

0.1µF

CLOCK

INPUT

CLK–

50kꢀ

Figure 66. Differential LVDS Sample Clock (Up to 1 GHz)

V

CC

OPTIONAL

100ꢀ

0.1µF

1

0.1µF

1kꢀ

AD951x

CMOS DRIVER

CLOCK

INPUT

CLK+

50ꢀ

ADC

CLK–

0.1µF

1

50ꢀ RESISTOR IS OPTIONAL.

Figure 67. Single-Ended 1.8 V CMOS Input Clock (Up to 200 MHz)

Rev. 0 | Page 25 of 40

AD9253

Data Sheet

Jitter Considerations

POWER DISSIPATION AND POWER-DOWN MODE

High speed, high resolution ADCs are sensitive to the quality of the

clock input. The degradation in SNR at a given input frequency

(f_A) due only to aperture jitter (t_J) can be calculated by

As shown in Figure 69, the power dissipated by the AD9253 is

proportional to its sample rate. The digital power dissipation

does not vary significantly because it is determined primarily by

the DRVDD supply and bias current of the LVDS output drivers.

350











1

SNR Degradation = 20 log

¹⁰



2  f_At_J

In this equation, the rms aperture jitter represents the root mean

square of all jitter sources, including the clock input, analog input

signal, and ADC aperture jitter specifications. IF undersampling

applications are particularly sensitive to jitter (see Figure 68).

300

125 MSPS

250

200

150

105 MSPS

80 MSPS

65 MSPS

The clock input should be treated as an analog signal in cases

where aperture jitter may affect the dynamic range of the AD9253.

Power supplies for clock drivers should be separated from the

ADC output driver supplies to avoid modulating the clock signal

with digital noise. Low jitter, crystal-controlled oscillators make

the best clock sources. If the clock is generated from another

type of source (by gating, dividing, or other methods), it should

be retimed by the original clock at the last step.

50 MSPS

40 MSPS

20 MSPS

100

10 20 30 40 50 60 70 80 90 100 110 120 130

SAMPLE RATE (MSPS)

Figure 69. Analog Core Power vs. f_SAMPLEfor f_IN= 10.3 MHz

Refer to the AN-501 Application Note and the AN-756

Application Note for more in-depth information about jitter

performance as it relates to ADCs.

The AD9253 is placed in power-down mode either by the SPI

port or by asserting the PDWN pin high. In this state, the ADC

typically dissipates 2 mW. During power-down, the output

drivers are placed in a high impedance state. Asserting the

PDWN pin low returns the AD9253 to its normal operating

mode. Note that PDWN is referenced to the digital output

driver supply (DRVDD) and should not exceed that supply

voltage.

130

RMS CLOCK JITTER REQUIREMENT

120

110

16 BITS

100

90

80

70

60

50

40

30

14 BITS

12 BITS

Low power dissipation in power-down mode is achieved by

shutting down the reference, reference buffer, biasing networks,

and clock. Internal capacitors are discharged when entering

power-down mode and then must be recharged when returning

to normal operation. As a result, wake-up time is related to the

time spent in power-down mode, and shorter power-down

cycles result in proportionally shorter wake-up times. When

using the SPI port interface, the user can place the ADC in

power-down mode or standby mode. Standby mode allows the

user to keep the internal reference circuitry powered when

faster wake-up times are required. See the Memory Map section

for more details on using these features.

10 BITS

8 BITS

0.125ps

0.25ps

0.5ps

1.0ps

2.0ps

1

10

100

1000

ANALOG INPUT FREQUENCY (MHz)

Figure 68. Ideal SNR vs. Input Frequency and Jitter

Rev. 0 | Page 26 of 40

Data Sheet

AD9253

DIGITAL OUTPUTS AND TIMING

The AD9253 differential outputs conform to the ANSI-644 LVDS

standard on default power-up. This can be changed to a low power,

reduced signal option (similar to the IEEE 1596.3 standard) via the

SPI. The LVDS driver current is derived on chip and sets the

output current at each output equal to a nominal 3.5 mA. A 100 Ω

differential termination resistor placed at the LVDS receiver

inputs results in a nominal 350 mV swing (or 700 mV p-p

differential) at the receiver.

When operating in reduced range mode, the output current is

reduced to 2 mA. This results in a 200 mV swing (or 400 mV p-p

differential) across a 100 Ω termination at the receiver.

D0 400mV/DIV

D1 400mV/DIV

DCO 400mV/DIV

FCO 400mV/DIV

4ns/DIV

The AD9253 LVDS outputs facilitate interfacing with LVDS

receivers in custom ASICs and FPGAs for superior switching

performance in noisy environments. Single point-to-point net

topologies are recommended with a 100 Ω termination resistor

placed as close to the receiver as possible. If there is no far-end

receiver termination or there is poor differential trace routing,

timing errors may result. To avoid such timing errors, it is

recommended that the trace length be less than 24 inches and

that the differential output traces be close together and at equal

lengths. An example of the FCO and data stream with proper

trace length and position is shown in Figure 70. Figure 71 shows

the LVDS output timing example in reduced range mode.

Figure 71. AD9253-125, LVDS Output Timing Example in Reduced Range Mode

An example of the LVDS output using the ANSI-644 standard

(default) data eye and a time interval error (TIE) jitter histo-

gram with trace lengths less than 24 inches on standard FR-4

material is shown in Figure 72.

500

EYE: ALL BITS

ULS: 7000/400354

400

300

200

100

0

–100

–200

–300

–400

–500

–0.8ns

–0.4ns

0ns

0.4ns

0.8ns

7k

6k

5k

4k

3k

2k

1k

0

D0 500mV/DIV

D1 500mV/DIV

DCO 500mV/DIV

FCO 500mV/DIV

4ns/DIV

Figure 70. AD9253-125, LVDS Output Timing Example in ANSI-644 Mode (Default)

200ps

250ps

300ps

350ps

400ps

450ps

500ps

Figure 72. Data Eye for LVDS Outputs in ANSI-644 Mode with Trace Lengths

Less than 24 Inches on Standard FR-4 Material, External 100 Ω Far-End

Termination Only

Rev. 0 | Page 27 of 40

AD9253

Data Sheet

Figure 73 shows an example of trace lengths exceeding 24 inches

on standard FR-4 material. Notice that the TIE jitter histogram

reflects the decrease of the data eye opening as the edge deviates

from the ideal position.

500

400

EYE: ALL BITS

ULS: 8000/414024

300

200

It is the user’s responsibility to determine if the waveforms

meet the timing budget of the design when the trace lengths

exceed 24 inches. Additional SPI options allow the user to further

increase the internal termination (increasing the current) of all

four outputs to drive longer trace lengths. This can be achieved

by programming Register 0x15. Even though this produces

sharper rise and fall times on the data edges and is less prone to

bit errors, the power dissipation of the DRVDD supply increases

when this option is used.

100

0

–100

–200

–300

–400

–500

–0.8ns

–0.4ns

0ns

0.4ns

–0.8ns

The format of the output data is twos complement by default.

An example of the output coding format can be found in Table 10.

To change the output data format to offset binary, see the

Memory Map section.

12k

10k

8k

Data from each ADC is serialized and provided on a separate

channel in two lanes in DDR mode. The data rate for each serial

stream is equal to 16 bits times the sample clock rate, with a

maximum of 500 Mbps/lane [(16 bits × 125 MSPS)/(2 × 2) =

500 Mbps/lane)]. The lowest typical conversion rate is 10 MSPS.

See the Memory Map section for details on enabling this feature.

6k

4k

2k

Two output clocks are provided to assist in capturing data from

the AD9253. The DCO is used to clock the output data and is

equal to four times the sample clock (CLK) rate for the default

mode of operation. Data is clocked out of the AD9253 and must

be captured on the rising and falling edges of the DCO that

supports double data rate (DDR) capturing. The FCO is used to

signal the start of a new output byte and is equal to the sample

clock rate in 1× frame mode. See the Timing Diagrams section

for more information.

0k

–800ps –600ps –400ps –200ps

0ps

200ps

400ps 600ps

Figure 73. Data Eye for LVDS Outputs in ANSI-644 Mode with Trace Lengths

Greater than 24 Inches on Standard FR-4 Material, External 100 Ω Far-End

Termination Only

Table 10. Digital Output Coding

Input (V)

Condition (V)

<−VREF − 0.5 LSB

−VREF

Offset Binary Output Mode

Twos Complement Mode

1000 0000 0000 0000

0000 0000 0000 0000

0111 1111 1111 1100

VIN+ − VIN−

0000 0000 0000 0000

1000 0000 0000 0000

1111 1111 1111 1100

0 V

+VREF − 1.0 LSB

>+VREF − 0.5 LSB

Rev. 0 | Page 28 of 40

Data Sheet

AD9253

Table 11. Flexible Output Test Modes

Output Test

Mode

Bit Sequence

Subject to

Data Format

Select

Pattern Name

Off (default)

Midscale short

Digital Output Word 1

Digital Output Word 2

Notes

0000

0001

N/A

Yes

1000 0000 0000 (12-bit)

1000 0000 0000 0000 (16-bit)

Offset binary

code shown

0010

0011

0100

0101

+Full-scale short

−Full-scale short

Checkerboard

1111 1111 1111 (12-bit)

0000 0000 0000 0000 (16-bit)

0000 0000 0000 (12-bit)

0000 0000 0000 0000 (16-bit)

1010 1010 1010 (12-bit)

1010 1010 1010 1010 (16-bit)

N/A

Yes

No

Yes

Offset binary

code shown

Offset binary

code shown

0101 0101 0101 (12-bit)

0101 0101 0101 0100 (16-bit)

N/A

PN sequence long¹

PN23

ITU 0.150

X²³+ X¹⁸+ 1

PN9

ITU 0.150

X⁹+ X⁵+ 1

0110

0111

PN sequence short¹N/A

N/A

Yes

No

One-/zero-word

toggle

1111 1111 1111 (12-bit)

111 1111 1111 1100 (16-bit)

0000 0000 0000 (12-bit)

0000 0000 0000 0000 (16-bit)

1000

1001

User input

1-/0-bit toggle

Register 0x19 to Register 0x1A Register 0x1B to Register 0x1C No

1010 1010 1010 (12-bit)

1010 1010 1010 1000 (16-bit)

0000 0011 1111 (12-bit)

0000 0001 1111 1100 (16-bit)

N/A

No

1010

1011

1× sync

One bit high

1000 0000 0000 (12-bit)

Pattern

associated

with the

1000 0000 0000 0000 (16-bit)

external pin

1100

Mixed frequency

1010 0011 0011 (12-bit)

N/A

No

1010 0001 1001 1100 (16-bit)

¹All test mode options except PN sequence short and PN sequence long can support 12-bit to 16-bit word lengths to verify data capture to the receiver.

patterns do not adhere to the data format select option. In

addition, custom user-defined test patterns can be assigned in

the 0x19, 0x1A, 0x1B, and 0x1C register addresses.

When the SPI is used, the DCO phase can be adjusted in 60°

increments relative to the data edge. This enables the user to

refine system timing margins if required. The default DCO+

and DCO− timing, as shown in Figure 2, is 90° relative to the

output data edge.

The PN sequence short pattern produces a pseudorandom bit

sequence that repeats itself every 2⁹− 1 or 511 bits. A

description of the PN sequence and how it is generated can be

found in Section 5.1 of the ITU-T 0.150 (05/96) standard. The

seed value is all 1s (see Table 12 for the initial values). The

output is a parallel representation of the serial PN9 sequence in

MSB-first format. The first output word is the first 14 bits of the

PN9 sequence in MSB aligned form.

A 12-bit serial stream can also be initiated from the SPI. This

allows the user to implement and test compatibility to lower

resolution systems. When changing the resolution to a 12-bit

serial stream, the data stream is shortened. See Figure 3 for the

12-bit example. However, in the default option with the serial

output number of bits at 16, the data stream stuffs two 0s at the

end of the 14-bit serial data.

The PN sequence long pattern produces a pseudorandom bit

sequence that repeats itself every 2²³− 1 or 8,388,607 bits. A

description of the PN sequence and how it is generated can be

found in Section 5.6 of the ITU-T 0.150 (05/96) standard. The

seed value is all 1s (see Table 12 for the initial values) and the

AD9253 inverts the bit stream with relation to the ITU standard.

The output is a parallel representation of the serial PN23 sequence

in MSB-first format. The first output word is the first 14 bits of the

PN23 sequence in MSB aligned form

In default mode, as shown in Figure 2, the MSB is first in the

data output serial stream. This can be inverted so that the LSB is

first in the data output serial stream by using the SPI.

There are 12 digital output test pattern options available that

can be initiated through the SPI. This is a useful feature when

validating receiver capture and timing. Refer to Table 11 for the

output bit sequencing options available. Some test patterns have

two serial sequential words and can be alternated in various

ways, depending on the test pattern chosen. Note that some

Rev. 0 | Page 29 of 40

AD9253

Data Sheet

Table 12. PN Sequence

and output data. This pin has an internal 10 kΩ resistor to GND.

It can be left unconnected.

Initial

Value

First Three Output Samples

(MSB First) Twos Complement

Sequence

Table 14. Digital Test Pattern Pin Settings

PN Sequence Short

PN Sequence Long

0x1FE0

0x1FFF

0x1DF1, 0x3CC8, 0x294E

0x1FE0, 0x2001, 0x1C00

Resulting

Selected DTP

Normal Operation

DTP

DTP Voltage

10 kΩ to AGND

AVDD

D0 x and D1 x

Consult the Memory Map section for information on how to

change these additional digital output timing features through

the SPI.

Normal operation

1000 0000 0000 0000

Additional and custom test patterns can also be observed when

commanded from the SPI port. Consult the Memory Map

section for information about the options available.

SDIO/OLM Pin

For applications that do not require SPI mode operation, the

CSB pin is tied to AVDD, and the SDIO/OLM pin controls the

output lane mode according to Table 13.

CSB Pin

The CSB pin should be tied to AVDD for applications that do

not require SPI mode operation. By tying CSB high, all SCLK

and SDIO information is ignored.

For applications where this pin is not used, CSB should be

tied to AVDD. When using the one-lane mode, the encode

rate should be ≤62.5 MSPS to meet the maximum output rate

of 1 Gbps.

RBIAS Pin

To set the internal core bias current of the ADC, place a

10.0 kΩ, 1% tolerance resistor to ground at the RBIAS pin.

Table 13. Output Lane Mode Pin Settings

OLM Pin

OUTPUT TEST MODES

Voltage

Output Mode

AVDD (Default)

GND

Two-lane. 1× frame, 16-bit serial output

One-lane. 1× frame, 16-bit serial output

The output test options are described in Table 11 and controlled by

the output test mode bits at Address 0x0D. When an output test

mode is enabled, the analog section of the ADC is disconnected

from the digital back-end blocks and the test pattern is run

through the output formatting block. Some of the test patterns

are subject to output formatting, and some are not. The PN

generators from the PN sequence tests can be reset by setting

Bit 4 or Bit 5 of Register 0x0D. These tests can be performed

with or without an analog signal (if present, the analog signal is

ignored), but they do require an encode clock. For more

information, see the AN-877 " QQMJDBUJPO / PUF, Interfacing to

High Speed ADCs via SPI.

SCLK/DTP Pin

The SCLK/DTP pin is for use in applications that do not require

SPI mode operation. This pin can enable a single digital test

pattern if it and the CSB pin are held high during device power-

up. When SCLK/DTP is tied to AVDD, the ADC channel

outputs shift out the following pattern: 1000 0000 0000 0000.

The FCO and DCO function normally while all channels shift out

the repeatable test pattern. This pattern allows the user to

perform timing alignment adjustments among the FCO, DCO,

Rev. 0 | Page 30 of 40

Data Sheet

AD9253

SERIAL PORT INTERFACE (SPI)

The falling edge of the CSB, in conjunction with the rising edge

of the SCLK, determines the start of the framing. An example of

the serial timing and its definitions can be found in Figure 74

and Table 5.

The AD9253 serial port interface (SPI) allows the user to configure

the converter for specific functions or operations through a

structured register space provided inside the ADC. The SPI

offers the user added flexibility and customization, depending on

the application. Addresses are accessed via the serial port and

can be written to or read from via the port. Memory is organized

into bytes that can be further divided into fields, which are docu-

mented in the Memory Map section. For detailed operational

information, see the AN-877 Application Note, Interfacing to

High Speed ADCs via SPI.

Other modes involving the CSB are available. The CSB can be

held low indefinitely, which permanently enables the device;

this is called streaming. The CSB can stall high between bytes to

allow for additional external timing. When CSB is tied high, SPI

functions are placed in high impedance mode. This mode turns

on any SPI pin secondary functions.

During an instruction phase, a 16-bit instruction is transmitted.

Data follows the instruction phase, and its length is determined

by the W0 and W1 bits.

CONFIGURATION USING THE SPI

Three pins define the SPI of this ADC: the SCLK pin, the SDIO

pin, and the CSB pin (see Table 15). The SCLK (a serial clock) is

used to synchronize the read and write data presented from and

to the ADC. The SDIO (serial data input/output) is a dual-

purpose pin that allows data to be sent to and read from the

internal ADC memory map registers. The CSB (chip select bar)

is an active low control that enables or disables the read and

write cycles.

In addition to word length, the instruction phase determines

whether the serial frame is a read or write operation, allowing

the serial port to be used both to program the chip and to read

the contents of the on-chip memory. The first bit of the first byte in

a multibyte serial data transfer frame indicates whether a read

command or a write command is issued. If the instruction is a

readback operation, performing a readback causes the serial

data input/output (SDIO) pin to change direction from an input to

an output at the appropriate point in the serial frame.

Table 15. Serial Port Interface Pins

Function

SCLK Serial clock. The serial shift clock input, which is used to

synchronize serial interface reads and writes.

SDIO Serial data input/output. A dual-purpose pin that

typically serves as an input or an output, depending on

the instruction being sent and the relative position in the

timing frame.

All data is composed of 8-bit words. Data can be sent in MSB-

first mode or in LSB-first mode. MSB-first mode is the default

on power-up and can be changed via the SPI port configuration

register. For more information about this and other features,

see the AN-877 Application Note, Interfacing to High Speed

ADCs via SPI.

CSB

Chip select bar. An active low control that gates the read

and write cycles.

t_HIGH

t_DS

t_CLK

t_H

t_S

t_DH

t_LOW

CSB

SCLK DON’T CARE

SDIO DON’T CARE

DON’T CARE

R/W

W1

W0

A12

A11

A10

A9

A8

A7

D5

D4

D3

D2

D1

D0

DON’T CARE

Figure 74. Serial Port Interface Timing Diagram

Rev. 0 | Page 31 of 40

AD9253

Data Sheet

When the device is in SPI mode, the PDWN pin (if enabled)

remains active. For SPI control of power-down, the PDWN pin

should be set to its default state.

HARDWARE INTERFACE

The pins described in Table 15 comprise the physical interface

between the user programming device and the serial port of the

AD9253. The SCLK pin and the CSB pin function as inputs

when using the SPI interface. The SDIO pin is bidirectional,

functioning as an input during write phases and as an output

during readback.

SPI ACCESSIBLE FEATURES

Table 16 provides a brief description of the general features that

are accessible via the SPI. These features are described in detail

in the AN-877 Application Note, Interfacing to High Speed ADCs

via SPI. The AD9253 part-specific features are described in detail

following Table 17, the external memory map register table.

The SPI interface is flexible enough to be controlled by either

FPGAs or microcontrollers. One method for SPI configuration

is described in detail in the AN-812 Application Note, Micro-

controller-Based Serial Port Interface (SPI) Boot Circuit.

Table 16. Features Accessible Using the SPI

Feature Name

Description

The SPI port should not be active during periods when the full

dynamic performance of the converter is required. Because the

SCLK signal, the CSB signal, and the SDIO signal are typically

asynchronous to the ADC clock, noise from these signals can

degrade converter performance. If the on-board SPI bus is used for

other devices, it may be necessary to provide buffers between

this bus and the AD9253 to prevent these signals from transi-

tioning at the converter inputs during critical sampling periods.

Power Mode

Allows the user to set either power-down mode

or standby mode

Allows the user to access the DCS, set the

clock divider, set the clock divider phase, and

enable the sync

Allows the user to digitally adjust the

converter offset

Allows the user to set test modes to have

known data on output bits

Clock

Offset

Test I/O

Some pins serve a dual function when the SPI interface is not

being used. When the pins are strapped to DRVDD or ground

during device power-on, they are associated with a specific

function. Table 16 describes the strappable functions supported

on the AD9253.

Output Mode

Output Phase

Allows the user to set the output mode

Allows the user to set the output clock polarity

ADC Resolution Allows for power consumption scaling with

respect to sample rate.

CONFIGURATION WITHOUT THE SPI

In applications that do not interface to the SPI control registers,

the SDIO/OLM pin, the SCLK/DTP pin, and the PDWN pin

serve as standalone CMOS-compatible control pins. When the

device is powered up, it is assumed that the user intends to use the

pins as static control lines for the duty cycle stabilizer, output

data format, and power-down feature control. In this mode,

CSB should be connected to AVDD, which disables the serial

port interface.

Rev. 0 | Page 32 of 40

Data Sheet

AD9253

MEMORY MAP

Default Values

READING THE MEMORY MAP REGISTER TABLE

After the AD9253 is reset, critical registers are loaded with

default values. The default values for the registers are given in

the memory map register table, Table 17.

Each row in the memory map register table has eight bit locations.

The memory map is roughly divided into three sections: the chip

configuration registers (Address 0x00 to Address 0x02); the device

index and transfer registers (Address 0x05 and Address 0xFF);

and the global ADC functions registers, including setup, control,

and test (Address 0x08 to Address 0x109).

Logic Levels

An explanation of logic level terminology follows:

•

“Bit is set” is synonymous with “bit is set to Logic 1” or

“writing Logic 1 for the bit.”

The memory map register table (see Table 17) lists the default

hexadecimal value for each hexadecimal address shown. The

column with the heading Bit 7 (MSB) is the start of the default

hexadecimal value given. For example, Address 0x05, the device

index register, has a hexadecimal default value of 0x3F. This

means that in Address 0x05, Bits[7:6] = 0, and the remaining

Bits[5:0] = 1. This setting is the default channel index setting.

The default value results in both ADC channels receiving the

next write command. For more information on this function

and others, see the AN-877 " QQMJDBUJPO / PUF, Interfacing to

High Speed ADCs via SPI. This application note details the

functions controlled by Register 0x00 to Register 0xFF. The

remaining registers are documented in the Memory Map

Register Descriptions section.

•

“Clear a bit” is synonymous with “bit is set to Logic 0” or

“writing Logic 0 for the bit.”

Channel-Specific Registers

Some channel setup functions, such as the signal monitor

thresholds, can be programmed differently for each channel. In

these cases, channel address locations are internally duplicated

for each channel. These registers and bits are designated in

Table 17 as local. These local registers and bits can be accessed

by setting the appropriate data channel bits (A, B, C, or D) and

the clock channel DCO bit (Bit 5) and FCO bit (Bit 4) in

Register 0x05. If all the bits are set, the subsequent write affects

the registers of all channels and the DCO/FCO clock channels.

In a read cycle, only one of the channels (A, B, C, or D) should

be set to read one of the four registers. If all the bits are set

during a SPI read cycle, the part returns the value for Channel

A. Registers and bits designated as global in Table 17 affect the

entire part or the channel features for which independent

settings are not allowed between channels. The settings in

Register 0x05 do not affect the global registers and bits.

Open Locations

All address and bit locations that are not included in Table 17

are not currently supported for this device. Unused bits of a

valid address location should be written with 0s. Writing to these

locations is required only when part of an address location is

open (for example, Address 0x05). If the entire address location

is open or not listed in Table 17 (for example, Address 0x13), this

address location should not be written.

Rev. 0 | Page 33 of 40

AD9253

Data Sheet

MEMORY MAP REGISTER TABLE

The AD9253 uses a 3-wire interface and 16-bit addressing and,

therefore, Bit 0 and Bit 7 in Register 0x00 are set to 0, and Bit 3

and Bit 4 are set to 1. When Bit 5 in Register 0x00 is set high,

the SPI enters a soft reset, where all of the user registers revert

to their default values and Bit 2 is automatically cleared.

Table 17.

Default

Value

(Hex)

ADDR

(Hex)

Bit 7

(MSB)

Bit 0

(LSB)

Parameter Name

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Comments

Chip Configuration Registers

0x00

SPI port

configuration

0 =

SDO

active

LSB first

Soft

reset

1 =

16-bit

address

1 =

16-bit

address

Soft

reset

LSB first

0 = SDO 0x18

active

The nibbles

are mirrored

so that LSB-

first or MSB-

first mode

registers

correctly. The

default for

ADCs is 16-bit

mode.

0x01

0x02

Chip ID (global)

8-bit chip ID, Bits[7:0]

AD9253 0x8F = quad 14-bit 80 MSPS/105 MSPS/125 MSPS serial LVDS

0x8F

Unique chip

ID used to

differentiate

devices; read

only.

Chip grade

(global)

Open

Speed grade ID[6:4]

100 = 80 MSPS

Open

Unique

speed grade

ID used to

differentiate

graded

101 = 105 MSPS

110 = 125 MSPS

devices; read

only.

Device Index and Transfer Registers

0x05

Device index

Open

Clock

Channel Channel

DCO

Clock

Data

Channel

D

Data

Channel

C

Data

Channel

B

Data

Channel

A

0x3F

Bits are set to

determine

which device

on chip

FCO

receives the

next write

command.

The default is

all devices on

chip.

0xFF

Transfer

Open

Initiate

override

0x00

Set resolution/

sample rate

override.

Global ADC Function Registers

0x08

Power modes

(global)

External

power-

down

Power mode

Determines

various

generic

modes of chip

operation.

00 = chip run

01 = full power-

down

10 = standby

11 = reset

function

0 = full

power-

down

1 =

standby

0x09

Clock (global)

Open

Duty

cycle

stabilize

0 = off

1 = on

0x01

Turns duty

cycle stabilizer

on or off.

Rev. 0 | Page 34 of 40

Data Sheet

AD9253

Default

Value

(Hex)

ADDR

(Hex)

Bit 7

(MSB)

Bit 0

(LSB)

Parameter Name

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Comments

0x0B

Clock divide

(global)

Open

Clock divide ratio[2:0]

000 = divide by 1

001 = divide by 2

010 = divide by 3

011 = divide by 4

100 = divide by 5

101 = divide by 6

110 = divide by 7

111 = divide by 8

0x00

0x0C

0x0D

Enhancement

control

Open

Chop

Open

0x00

Enables/

disables chop

mode.

mode

0 = off

1 = on

Test mode (local

except for PN

sequence resets)

User input test mode

00 = single

Reset

PN long

gen

Reset PN

short

gen

Output test mode[3:0] (local)

0000 = off (default)

When set, the

test data is

placed on the

output pins in

place of

0001 = midscale short

0010 = positive FS

0011 = negative FS

01 = alternate

10 = single once

11 = alternate once

(affects user input test

mode only,

0100 = alternating checkerboard

0101 = PN 23 sequence

0110 = PN 9 sequence

0111 = one/zero word toggle

1000 = user input

normal data.

Bits[3:0] = 1000)

1001 = 1-/0-bit toggle

1010 = 1× sync

1011 = one bit high

1100 = mixed bit frequency

0x10

0x14

Offset adjust

(local)

8-bit device offset adjustment [7:0] (local)

Offset adjust in LSBs from +127 to −128 (twos complement format)

0x00

0x01

Device offset

trim.

Output mode

Open

LVDS-ANSI/

LVDS-IEEE

option

0 = LVDS-

ANSI

Open

Output

invert

(local)

Open

Output

format

0 =

offset

binary

1 =

Configures

the outputs

and the

format of the

data.

1 = LVDS-

IEEE

twos

reduced

range link

(global)

see

comple-

ment

(global)

Table 18

0x15

0x16

Output adjust

Output phase

Open

Output driver

termination[1:0]

00 = none

01 = 200 Ω

10 = 100 Ω

Open

Output

drive

0 = 1×

drive

1 = 2×

drive

0x00

0x03

Determines

LVDS or other

output

properties.

11 = 100 Ω

Input clock phase adjust[6:4]

(value is number of input clock

cycles of phase delay)

see Table 19

Output clock phase adjust[3:0]

(0000 through 1011)

see Table 20

On devices

that use

global clock

divide,

determines

which phase

of the divider

output is used

to supply the

output clock.

Internal

latching is

unaffected.

Rev. 0 | Page 35 of 40

AD9253

Data Sheet

Default

ADDR

(Hex)

Bit 7

(MSB)

Bit 0

(LSB)

Value

(Hex)

Parameter Name

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Comments

0x18

V_REF

Open

Internal V_REFadjustment

digital scheme[2:0]

000 = 1.0 V p-p

0x04

Selects and/or

adjusts the

V_REF

.

001 = 1.14 V p-p

010 = 1.33 V p-p

011 = 1.6 V p-p

100 = 2.0 V p-p

0x19

0x1A

0x1B

0x1C

0x21

USER_PATT1_LSB

(global)

B7

B6

B5

B4

B3

B2

B1

B9

B1

B9

B0

B8

B0

B8

0x00

0x30

User Defined

Pattern 1 LSB.

USER_PATT1_MSB

(global)

B15

B7

B14

B6

B13

B5

B12

B4

B11

B3

B10

B2

User Defined

Pattern 1 MSB.

USER_PATT2_LSB

(global)

User Defined

Pattern 2 LSB.

USER_PATT2_MSB

(global)

B15

B14

B13

B12

B11

Open

B10

User Defined

Pattern 2 MSB.

Serial output data

control (global)

LVDS

output

LSB

SDR/DDR one-lane/two-lane,

bitwise/bytewise[6:4]

Select

2×

frame

Serial output

number of bits

00 = 16 bits

Serial stream

control.

Default causes

MSB first and

the native bit

stream.

000 = SDR two-lane, bitwise

001 = SDR two-lane, bytewise

010 = DDR two-lane, bitwise

011 = DDR two-lane, bytewise

100 = DDR one-lane

first

10 = 12 bits

0x22

Serial channel

status (local)

Open

Channel

output

reset

Channel 0x00

power-

down

Used to power

down

individual

sections of a

converter.

0x100

Resolution/

sample rate

override

Resolution/

sample rate

override

Resolution

01 = 14 bits

10 = 12 bits

Sample rate

000 = 20 MSPS

001 = 40 MSPS

010 = 50 MSPS

011 = 65 MSPS

100 = 80 MSPS

101 = 105 MSPS

110 = 125 MSPS

0x00

Resolution/

sample rate

override

(requires

transfer

enable

register, 0xFF).

0x101

0x102

0x109

User I/O Control 2

User I/O Control 3

Sync

Open

SDIO

pull-

down

0x00

Disables SDIO

pull-down.

Open

VCM

power-

down

Open

VCM control.

Open

Sync

Enable

sync

Rev. 0 | Page 36 of 40

Data Sheet

AD9253

Output Mode (Register 0x14)

Bit 7—Open

MEMORY MAP REGISTER DESCRIPTIONS

For additional information about functions controlled in

Register 0x00 to Register 0xFF, see the AN-877 Application Note,

Interfacing to High Speed ADCs via SPI.

Bit 6—LVDS-ANSI/LVDS-IEEE Option

Setting this bit chooses LVDS-IEEE (reduced range) option.

The default setting is LVDS-ANSI. As described in Table 18,

when LVDS-ANSI or LVDS-IEEE reduced range link is selected,

the user can select the driver termination. The driver current

is automatically selected to give the proper output swing.

Device Index (Register 0x05)

There are certain features in the map that can be set inde-

pendently for each channel, whereas other features apply

globally to all channels (depending on context) regardless of

which are selected. The first four bits in Register 0x05 can be

used to select which individual data channels are affected. The

output clock channels can be selected in Register 0x05 as well. A

smaller subset of the independent feature list can be applied to

those devices.

Table 18. LVDS-ANSI/LVDS-IEEE Options

Output

Mode,

Bit 6

Output

Driver

Termination

Output

Mode

Output Driver

Current

0

LVDS-ANSI

User

Automatically

selected to give

proper swing

Automatically

selected to give

proper swing

selectable

Transfer (Register 0xFF)

All registers except Register 0x100 are updated the moment

they are written. Setting Bit 0 of this transfer register high

initializes the settings in the ADC sample rate override register

(Address 0x100).

1

LVDS-IEEE

reduced

User

selectable

range link

Bits[5:3]—Open

Power Modes (Register 0x08)

Bits[7:6]—Open

Bit 2—Output Invert

Setting this bit inverts the output bit stream.

Bit 1—Open

Bit 5—External Power-Down Pin Function

If set, the external PDWN pin initiates power-down mode. If

cleared, the external PDWN pin initiates standby mode.

Bit 0—Output Format

By default, this bit is set to send the data output in twos

complement format. Resetting this bit changes the output mode

to offset binary.

Bits[4:2]—Open

Bits[1:0]—Power Mode

In normal operation (Bits[1:0] = 00), all ADC channels are

active.

Output Adjust (Register 0x15)

Bits[7:6]—Open

In power-down mode (Bits[1:0] = 01), the digital datapath clocks

are disabled while the digital datapath is reset. Outputs are

disabled.

Bits[5:4]—Output Driver Termination

These bits allow the user to select the internal termination

resistor.

In standby mode (Bits[1:0] = 10), the digital datapath clocks

and the outputs are disabled.

Bits[3:1]—Open

Bit 0—Output Drive

During a digital reset (Bits[1:0] = 11), all the digital datapath

clocks and the outputs (where applicable) on the chip are reset,

except the SPI port. Note that the SPI is always left under

control of the user; that is, it is never automatically disabled or

in reset (except by power-on reset).

Bit 0 of the output adjust register controls the drive strength on

the LVDS driver of the FCO and DCO outputs only. The default

values set the drive to 1× while the drive can be increased to 2×

by setting the appropriate channel bit in Register 0x05 and then

setting Bit 0. These features cannot be used with the output

driver termination select. The termination selection takes

precedence over the 2× driver strength on FCO and DCO when

both the output driver termination and output drive are selected.

Enhancement Control (Register 0x0C)

Bits[7:3]—Open

Bit 2—Chop Mode

For applications that are sensitive to offset voltages and other

low frequency noise, such as homodyne or direct conversion

receivers, chopping in the first stage of the AD9253 is a feature

that can be enabled by setting Bit 2. In the frequency domain,

chopping translates offsets and other low frequency noise to

Output Phase (Register 0x16)

Bit 7—Open

Bits[6:4]—Input Clock Phase Adjust

f

_CLK/2 where it can be filtered.

Bits[1:0]—Open

Rev. 0 | Page 37 of 40

AD9253

Data Sheet

Table 19. Input Clock Phase Adjust Options

Serial Output Data Control (Register 0x21)

Input Clock Phase

Adjust, Bits[6:4]

Number of Input Clock Cycles of

Phase Delay

The serial output data control register is used to program the

AD9253 in various output data modes depending upon the data

capture solution. Table 21 describes the various serialization

options available in the AD9253.

000 (Default)

001

010

011

100

101

110

111

0

1

2

3

4

5

6

7

Resolution/Sample Rate Override (Register 0x100)

This register is designed to allow the user to downgrade the device.

Any attempt to upgrade the default speed grade results in a chip

power-down. Settings in this register are not initialized until Bit 0

of the transfer register (Register 0xFF) is written high.

User I/O Control 2 (Register 0x101)

Bits[7:1]—Open

Bits[3:0]—Output Clock Phase Adjust

Table 20. Output Clock Phase Adjust Options

Bit 0—SDIO Pull-Down

Output Clock (DCO),

DCO Phase Adjustment (Degrees

Bit 0 can be set to disable the internal 30 kꢁ pull-down on the

SDIO pin, which can be used to limit the loading when many

devices are connected to the SPI bus.

Phase Adjust, Bits[3:0]

Relative to D0 x/D1 x Edge)

0000

0001

0

60

0010

0011 (Default)

0100

0101

0110

0111

1000

1001

1010

120

180

240

300

360

420

480

540

600

660

User I/O Control 3 (Register 0x102)

Bits[7:4]—Open

Bit 3—VCM Power-Down

Bit 3 can be set high to power down the internal VCM

generator. This feature is used when applying an external

reference.

Bits[2:0]—Open

1011

Table 21. SPI Register Options

Serialization Options Selected

Register 0x21

Contents

Serial Output Number

of Bits (SONB)

16-bit

12-bit

Frame Mode

Serial Data Mode

DCO Multiplier

4 × f_S

8 × f_S

4 × f_S

8 × f_S

3 × f_S

6 × f_S

3 × f_S

6 × f_S

Timing Diagram

Figure 2 (default setting)

Figure 2

Figure 4

Figure 6

Figure 3

Figure 5

0x30

0x20

0x10

0x00

0x34

0x24

0x14

0x04

0x40

0x32

0x22

0x12

0x02

0x36

0x26

0x16

0x06

0x42

1×

2×

1×

2×

1×

DDR two-lane bytewise

DDR two-lane bitwise

SDR two-lane bytewise

SDR two-lane bitwise

DDR two-lane bytewise

DDR two-lane bitwise

SDR two-lane bytewise

SDR two-lane bitwise

DDR one-lane

DDR two-lane bytewise

DDR two-lane bitwise

SDR two-lane bytewise

SDR two-lane bitwise

DDR two-lane bytewise

DDR two-lane bitwise

SDR two-lane bytewise

SDR two-lane bitwise

DDR one-lane

6 × f_S

Figure 5

Figure 7

Rev. 0 | Page 38 of 40

Data Sheet

AD9253

APPLICATIONS INFORMATION

DESIGN GUIDELINES

VCM

The VCM pin should be decoupled to ground with a 0.1 ꢀF

capacitor.

Before starting design and layout of the AD9253 as a system,

it is recommended that the designer become familiar with these

guidelines, which describes the special circuit connections and

layout requirements that are needed for certain pins.

REFERENCE DECOUPLING

The VREF pin should be externally decoupled to ground with a

low ESR, 1.0 ꢀF capacitor in parallel with a low ESR, 0.1 ꢀF

ceramic capacitor.

POWER AND GROUND RECOMMENDATIONS

When connecting power to the AD9253, it is recommended

that two separate 1.8 V supplies be used. Use one supply for

analog (AVDD); use a separate supply for the digital outputs

(DRVDD). For both AVDD and DRVDD, several different

decoupling capacitors should be used to cover both high and

low frequencies. Place these capacitors close to the point of

entry at the PCB level and close to the pins of the part, with

minimal trace length.

SPI PORT

The SPI port should not be active during periods when the full

dynamic performance of the converter is required. Because the

SCLK, CSB, and SDIO signals are typically asynchronous to the

ADC clock, noise from these signals can degrade converter

performance. If the on-board SPI bus is used for other devices,

it may be necessary to provide buffers between this bus and the

AD9253 to keep these signals from transitioning at the con-

verter inputs during critical sampling periods.

A single PCB ground plane should be sufficient when using the

AD9253. With proper decoupling and smart partitioning of the

PCB analog, digital, and clock sections, optimum performance

is easily achieved.

CROSSTALK PERFORMANCE

The AD9253 is available in a 48-lead LFCSP package with the

input pairs on either corner of the chip. See Figure 9 for the pin

configuration. To maximize the crosstalk performance on the

board, add grounded filled vias in between the adjacent

channels as shown in Figure 76.

EXPOSED PAD THERMAL HEAT SLUG

RECOMMENDATIONS

It is required that the exposed pad on the underside of the ADC

be connected to analog ground (AGND) to achieve the best

electrical and thermal performance of the AD9253. An exposed

continuous copper plane on the PCB should mate to the

AD9253 exposed pad, Pin 0. The copper plane should have

several vias to achieve the lowest possible resistive thermal path

for heat dissipation to flow through the bottom of the PCB.

These vias should be solder-filled or plugged.

To maximize the coverage and adhesion between the ADC and

PCB, partition the continuous copper plane by overlaying a

silkscreen on the PCB into several uniform sections. This provides

several tie points between the ADC and PCB during the reflow

process, whereas using one continuous plane with no partitions

only guarantees one tie point. See Figure 75 for a PCB layout

example. For detailed information on packaging and the PCB

layout of chip scale packages, see the AN-772 " QQMJDBUJPO / PUF,

A Design and Manufacturing Guide for the Lead Frame Chip

Scale Package (LFCSP), at www.analog.com.

VIN

CHANNEL A

GROUNDED

FILLED VIAS

VIN

FOR ADDED

CHANNEL D

CROSSTALK

ISOLATION

PIN 1

VIN

CHANNEL B

VIN

CHANNEL C

Figure 76. Layout Technique to Maximize Crosstalk Performance

SILKSCREEN PARTITION

PIN 1 INDICATOR

Figure 75. Typical PCB Layout

Rev. 0 | Page 39 of 40

AD9253

Data Sheet

OUTLINE DIMENSIONS

7.10

7.00 SQ

6.90

0.30

0.23

0.18

PIN 1

INDICATOR

PIN 1

INDICATOR

37

36

48

1

0.50

BSC

EXPOSED

PAD

5.65

5.60 SQ

5.55

24

13

0.45

0.40

0.35

0.20 MIN

TOP VIEW

BOTTOM VIEW

FOR PROPER CONNECTION OF

THE EXPOSED PAD, REFER TO

THE PIN CONFIGURATION AND

FUNCTION DESCRIPTIONS

0.80

0.75

0.70

0.05 MAX

0.02 NOM

SECTION OF THIS DATA SHEET.

COPLANARITY

0.08

0.20 REF

SEATING

PLANE

COMPLIANT TO JEDEC STANDARDS MO-220-WKKD.

Figure 77. 48-Lead Lead Frame Chip Scale Package [LFCSP_WQ]

7 mm × 7 mm Body, Very Very Thin Quad

(CP-48-13)

Dimensions shown in millimeters

ORDERING GUIDE

Model¹

Temperature Range

−40°C to +85°C

Package Description

Package Option

CP-48-13

AD9253BCPZ-80

AD9253BCPZRL7-80

AD9253BCPZ-105

AD9253BCPZRL7-105

AD9253BCPZ-125

AD9253BCPZRL7-125

AD9253-125EBZ

48-Lead Lead Frame Chip Scale Package (LFCSP_WQ)

Evaluation Board

−40°C to +85°C

CP-48-13

¹Z = RoHS Compliant Part.

registered trademarks are the property of their respective owners.

D10065-0-10/11(0)

Rev. 0 | Page 40 of 40


型号：	AD9253BCPZRL7-105
厂家：	ADI
描述：	Quad, 14-Bit, 80 MSPS/105 MSPS/125 MSPS 四通道，14位， 80 MSPS / 105 MSPS / 125 MSPS 转换器模数转换器
文件：	总40页 (文件大小：1264K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

AD9253BCPZRL7-105 [ADI]

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