A7220M8R_技术文档

A7220

AiT Semiconductor Inc.

www.ait-ic.com

DC-DC CONVERTER BUCK (STEP-DOWN)

4.3V TO 18V INPUT, 2A SYNCHRONOUS STEP-DOWN

CONVERTER WITH FAST TRANSIENT RESPONSE

DESCRIPTION

FEATURES

The A7220 is a current mode synchronous

buck converter, and has proprietary



2A Output Current

High Efficient Integrated FETs Optimized for portable

application:

95mΩ (High side) and 90mΩ (Low side)

High Efficiency

Up to 95% Efficiency @ 5V Input, 3.3V Output

Up to 93% Efficiency @ 12V Input, 3.3V Output

Wide Input Voltage Range: 4.3V to 18V @ 2A loading

Wide Output Voltage Range: 0.918V to 14V @2A

loading ( 32W output @max)

Low Output Ripple and Allows Ceramic Output Capacitor

Thermal Shutdown Protection

340KHz Switching Frequency(fsw)

Cycle By Cycle Over Current Limit

+/-1.5% High Accuracy Feedback Voltage

Available in SOP8 and package

a

W-mode™® Gm curvature circuit that enables

fast transient response, enables the device to

adopt to both low ESR output capacitors, such

as POSCAP or SP-CAP, and ultra-low ESR

ceramic capacitors.



The A7220 operates from 4.3V to 18V V_IN

input, and the output voltage can be

programmed between 0.918V to 14V with 2A

output current, and +/-1.5% high accuracy

output voltage.



Due to 95mΩ (High side) and 90mΩ (Low

side) integrated FETs, the A7220 works in high

efficiency (up to 94% @12V Input, 3.3V output)

The A7220 is available in SOP8 Package.

APPLICATION



Wide Range of Applications for Low Voltage System

ORDERING INFORMATION

Digital TV Power Supply

High Definition Blu-ray Disc Players

Networking Home Terminal

Digital STB

Package Type

SOP8

Part Number

A7220M8R

A7220M8VR

Ideal for Portable Applications

M

R: Tape & Reel

Note

TYPICAL APPLICATION

V: Halogen free Package

AiT provides all RoHS products

Suffix “ V “ means Halogen free Package

REV3.0

- JUL 2010 RELEASED, FEB 2012 UPDATED -

- 1 -

A7220

AiT Semiconductor Inc.

www.ait-ic.com

DC-DC CONVERTER BUCK (STEP-DOWN)

4.3V TO 18V INPUT, 2A SYNCHRONOUS STEP-DOWN

CONVERTER WITH FAST TRANSIENT RESPONSE

PIN DESCRIPTION

Top View

Pin #

1

Symbol

BS

Function

Supply input for high-side NFET gate driver (boost terminal). Connect

capacitor from this pin to SW pin. An internal PN diode is connected

between V_REGto BS pin.

2

3

IN

Power input and connected to high side NFET drain

Switch node connection between high-side NFET and low-side NFET.

Also serve as inputs to current comparators.

SW

4

5

GND

FB

Signal ground pin, also serve as ground returns for low-side NFET.

Converter feedback input. Connect with feedback resistor divider.

Compensation Node. Used to compensate control loop. Connect a

series RC network from COMP to G. In some cases, an additional

capacitor is required

6

COMP

7

8

EN

SS

Enable control input

Soft-start control. A external capacitor should be connected to GND.

REV3.0

- JUL 2010 RELEASED, FEB 2012 UPDATED -

- 2 -

A7220

AiT Semiconductor Inc.

www.ait-ic.com

DC-DC CONVERTER BUCK (STEP-DOWN)

4.3V TO 18V INPUT, 2A SYNCHRONOUS STEP-DOWN

CONVERTER WITH FAST TRANSIENT RESPONSE

ABSOLUTE MAXIMUM RATINGS

IN

-0.3V to 20V

-0.3V to 25V

-2V to 20V

BS

SW

Voltage Range

SW (10 ns transient)

-2.5V to 21V

-0.3V to 5.5V

-0.3V to 8V

FB,SS,COMP

EN

T_J, Operation Junction

T_STG, Storage temperature

-40℃ to +150℃

-55℃ to +150℃

Stresses above may cause permanent damage to the device. These are stress ratings only and functional operation of the device at

these or any other conditions beyond those indicated in the Electrical Characteristics are not implied. Exposure to absolute maximum

rating conditions for extended periods may affect device reliability.

REV3.0

- JUL 2010 RELEASED, FEB 2012 UPDATED -

- 3 -

A7220

AiT Semiconductor Inc.

www.ait-ic.com

DC-DC CONVERTER BUCK (STEP-DOWN)

4.3V TO 18V INPUT, 2A SYNCHRONOUS STEP-DOWN

CONVERTER WITH FAST TRANSIENT RESPONSE

ELECTRICAL CHARACTERISTICS

Over operating free-air temperature range(unless otherwise noted) V_IN=12V, T_A=25℃

Parameter

Operating-non-switching supply

current

Symbol

Conditions

V_INcurrent, T_A=25℃,

EN=1.8V,V_FB=1.0V

V_EN=0V

Min

Typ.

Max

2.0

Unit

mA

I_IN

-

1.3

Shut Down Supply Current

Feedback Voltage

Feedback Overvoltage

Threshold

ISDN

V_FB

-

2

4

μA

V

4.3V ≤V_IN≤18V

0.900

0.913

0.926

OVP

Aea

Gea

-

1.1

1000

900

-

V

Error Amplifier Voltage Gain

Error Amplifier

V/V

μA/V

ΔIC=+/-10μA

Transconductance

High Side Switch ON Resistance R_DS(on)_1

Low Side Switch ON Resistance R_DS(on)_2

High Side Switch Leakage

-

95

90

-

mΩ

I_LEAKGAEV_EN=0V, V_SW=0V

-

10

μA

Current

High Side Switch Current Limit

Low Side Switch Current Limit

COMP Voltage to Current Sense

Transconductance

I_{LM_H}

I_{LM_L}

Minimum Duty Cycle

From Drain to Source

2.8

-

3.5

1.0

-

A

Gcs

-

3.5

340

100

-

A/V

KHz

Switching Frequency

Short Circuit Switching

Frequency

Fsw_1

Fsw_2

V_FB=0V

Maximum Duty Cycle

Minimum ON Time

Dmax

T_{ON_min}

V_EN_1

V_FB=1.0V

90

220

1.5

-

%

ns

V

EN Threshold Voltage

EN Threshold voltage’s

Hysteresis

V_ENRising

1.1

-

2.0

V_Hys_1

100

-

mV

EN Lockout Threshold Voltage

EN Lockout Hysteresis

Input Under Voltage Lockout

Threshold

V_EN_2

V_Hys_2

1.8

-

2.0

2.2

-

V

210

mV

V_UVLO

V_INRising

3.0

3.6

4.2

V

REV3.0

- JUL 2010 RELEASED, FEB 2012 UPDATED -

- 4 -

A7220

AiT Semiconductor Inc.

www.ait-ic.com

DC-DC CONVERTER BUCK (STEP-DOWN)

4.3V TO 18V INPUT, 2A SYNCHRONOUS STEP-DOWN

CONVERTER WITH FAST TRANSIENT RESPONSE

Parameter

Conditions

Symbol

V_Hys_3

I_SS

Min

Typ.

600

Max

4.55

Unit

mV

μA

Input Under Voltage Lockout

Threshold Hysteresis

Soft-Start Current

V_SS=0V

4.25

4.40

Setting Feedback Voltage by

Using Soft-Start Voltage

Only when VSS <

0.85V by adding

resistor on SS pin

VSS=

VSS+30

mV

VFB-SS

mV

Iss*RSS=4.4μA*RSS

C_SS=0.1μF

Soft-Start Period

T_SS

15

ms

℃

Thermal Shutdown

TSD

160

REV3.0

- JUL 2010 RELEASED, FEB 2012 UPDATED -

- 5 -

A7220

AiT Semiconductor Inc.

www.ait-ic.com

DC-DC CONVERTER BUCK (STEP-DOWN)

4.3V TO 18V INPUT, 2A SYNCHRONOUS STEP-DOWN

CONVERTER WITH FAST TRANSIENT RESPONSE

TEST CIRCUIT

V_IN=12V,V_OUT=3.3V, L=10μH, C_IN=10μF, C_OUT=22μF, T_A=+25℃

1. Fast Transient Response (20A/μs) 2. Startup through Enable

3. 1A Load Operation

4. 2A Load Operation

5. Shutdown through Enable

6. Short Circuit Recovery

REV3.0

- JUL 2010 RELEASED, FEB 2012 UPDATED -

- 6 -

A7220

AiT Semiconductor Inc.

www.ait-ic.com

DC-DC CONVERTER BUCK (STEP-DOWN)

4.3V TO 18V INPUT, 2A SYNCHRONOUS STEP-DOWN

CONVERTER WITH FAST TRANSIENT RESPONSE

APPLICATION INFORMATION

APPLICATION SCHEMATIC (1)

With Electrolytic Capacitor

Figure 1

Compatible with main competitors without any external component change

RECOMMENDED COMPONENT SELECTION

V_OUT

1.0V

1.2V

1.8V

2.5V

3.3V

5.0V

1.0V

1.2V

1.8V

2.5V

3.3V

5.0V

C_OUT

22Μf Ceramic X2

22μF Ceramic X2

47μF SP Cap

R1

R2

R3(comp)

50Ω

C4(comp)

10nF

C5(optional) L(inductor)

1.0K

10K

15K

10K

6.8K

10K

6.8K

10K

15K

10K

6.8K

10K

6.8K

OPEN

3.3μH

4.7μH

6.8μH

10μH

22μH

3.3μH

4.7μH

6.8μH

10μH

22μH

4.7K

100Ω

300Ω

1.5KΩ

2.2KΩ

2.7KΩ

50Ω

10nF

9.7K

3.3nF

10nF

12.0K

26.1K

30.0K

1.0K

47μF SP Cap

4.7K

100Ω

300Ω

1.5KΩ

2.2KΩ

2.7KΩ

10nF

47μF SP Cap

9.7K

3.3nF

47μF SP Cap

12.0K

26.1K

30.0K

47μF SP Cap

REV3.0

- JUL 2010 RELEASED, FEB 2012 UPDATED -

- 7 -

A7220

AiT Semiconductor Inc.

www.ait-ic.com

DC-DC CONVERTER BUCK (STEP-DOWN)

4.3V TO 18V INPUT, 2A SYNCHRONOUS STEP-DOWN

CONVERTER WITH FAST TRANSIENT RESPONSE

V_OUT

1.0V

1.2V

1.8V

2.5V

3.3V

5.0V

12V

C_OUT

R1

R2

R3(comp)

50Ω

C4(comp)

10nF

C5(optional)

150pF

L(inductor)

3.3μH

4.7μH

6.8μH

10μH

470μF/6.3V/Electrolytic

1.0K

4.7K

9.7K

10K

15K

10K

6.8K

10K

6.8K

5.1K

100Ω

10nF

300Ω

3.3nF

470μF/6.3V/Electrolytic 12.0K

470μF/6.3V/Electrolytic 26.1K

1.5KΩ

2.2KΩ

2.7KΩ

3.3KΩ

470μF/10V/Electrolytic

470μF/25V/Electrolytic

30.0K

62.0K

22μH

47μH

REV3.0

- JUL 2010 RELEASED, FEB 2012 UPDATED -

- 8 -

A7220

AiT Semiconductor Inc.

www.ait-ic.com

DC-DC CONVERTER BUCK (STEP-DOWN)

4.3V TO 18V INPUT, 2A SYNCHRONOUS STEP-DOWN

CONVERTER WITH FAST TRANSIENT RESPONSE

APPLICATION SCHEMATIC (2)

Fast Transient Response Without Electrolytic Capacitor

Figure 2

RECOMMENDED COMPONENT SELECTION

V_OUT

1.0V

1.2V

1.8V

2.5V

3.3V

5.0V

1.0V

1.2V

1.8V

2.5V

3.3V

5.0V

C_OUT

R1

R2

R3(comp)

3.0KΩ

C4(comp)

1.0nF

Cff

L(inductor)

2.2μH

3.3μH

4.7μH

6.8μH

22μH

22μF Ceramic X2

47μF SP Cap

2.0K

20K

2.2nF

1.0nF

680pF

390pF

2.2nF

1.0nF

680pF

390pF

6.3K

19.4K

34.5K

52.2K

89.5K

2.0K

2.2μH

3.3μH

4.7μH

6.8μH

22μH

47μF SP Cap

6.3K

47μF SP Cap

19.4K

34.5K

52.2K

89.5K

47μF SP Cap

REV3.0

- JUL 2010 RELEASED, FEB 2012 UPDATED -

- 9 -

A7220

AiT Semiconductor Inc.

www.ait-ic.com

DC-DC CONVERTER BUCK (STEP-DOWN)

4.3V TO 18V INPUT, 2A SYNCHRONOUS STEP-DOWN

CONVERTER WITH FAST TRANSIENT RESPONSE

APPLICATION NOTES

a) C2 ceramic capacitor as close as possible to the chip PIN2 and PIN4 placed;

b) When using 47μH inductors, each switching and transmission of energy, the output of the

need for greater capacitance, so that the large-signal. The feedback loop is stable. 47μH

inductor, the output is required with greater than or equal to 330μF electrolytic capacitor

for energy Bulk.

c) The current path is as short as possible and as far as possible with the chip in the same

PCB level. Played the hole cross-layer connections to avoid the high current path.

d) If feasible, cost and high efficiency design, should make full use of ceramic capacitors or

smaller ESR (such as: 30mohm) electrolytic Capacity, efficiency can be effectively

increased by 1%.

e) EN pin (pin 7) on the pull-up resistor is not less than 100KΩ.

f) If more than one chip share the same input capacitance of the need to adjust of 8

Jiaoruan starting capacitor capacitance value of time-delayed start of each chip to

regulate avoid multiple chip start to impact on the power input capacitance. Delay Time:

delay 15ms per 100nF capacitor.

REV3.0

- JUL 2010 RELEASED, FEB 2012 UPDATED -

- 10 -

A7220

AiT Semiconductor Inc.

www.ait-ic.com

DC-DC CONVERTER BUCK (STEP-DOWN)

4.3V TO 18V INPUT, 2A SYNCHRONOUS STEP-DOWN

CONVERTER WITH FAST TRANSIENT RESPONSE

PACKAGE INFORMATION

Dimension in SOP8 (Unit: mm)

Symbol

Min

Max

A

A1

A2

b

1.350

0.100

1.350

0.330

0.170

4.700

3.800

5.800

1.750

0.250

1.550

0.510

0.250

5.100

4.000

6.200

c

D

E

E1

e

1.270(BSC)

0.400

0°

L

1.270

8°

θ

REV3.0

- JUL 2010 RELEASED, FEB 2012 UPDATED -

- 11 -

A7220

AiT Semiconductor Inc.

www.ait-ic.com

DC-DC CONVERTER BUCK (STEP-DOWN)

4.3V TO 18V INPUT, 2A SYNCHRONOUS STEP-DOWN

CONVERTER WITH FAST TRANSIENT RESPONSE

IMPORTANT NOTICE

AiT Semiconductor Inc. (AiT) reserves the right to make changes to any its product, specifications, to

discontinue any integrated circuit product or service without notice, and advises its customers to obtain the

latest version of relevant information to verify, before placing orders, that the information being relied on is

current.

AiT Semiconductor Inc.'s integrated circuit products are not designed, intended, authorized, or warranted to

be suitable for use in life support applications, devices or systems or other critical applications. Use of AiT

products in such applications is understood to be fully at the risk of the customer. As used herein may

involve potential risks of death, personal injury, or servere property, or environmental damage. In order to

minimize risks associated with the customer's applications, the customer should provide adequate design and

operating safeguards.

AiT Semiconductor Inc. assumes to no liability to customer product design or application support. AiT

warrants the performance of its products of the specifications applicable at the time of sale.

REV3.0

- JUL 2010 RELEASED, FEB 2012 UPDATED -

- 12 -


型号：	A7220M8R
厂家：	AiT Semiconductor
描述：	DC-DC CONVERTER BUCK (STEP-DOWN) DC-DC转换器
文件：	总12页 (文件大小：479K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

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