MAX1234ETI_技术文档

19-2512; Rev 3; 8/05

1ꢀ5k ꢁEDꢂ-rotected TouchꢂEcreen

Controllers Include DAC and Keypad Controller

General Description

Features

The MAX1233/MAX1234 are complete PDA controllers in

5mm × 5mm, 28-pin QFN and TQFN packages. They fea-

ture a 12-bit analog-to-digital converter (ADC), low on-

resistance switches for driving resistive touch screens, an

internal +1.0V/+2.5V or external reference, 2°C accu-

rate, on-chip temperature sensor, direct +6V battery mon-

itor, keypad controller, 8-bit digital-to-analog converter

(DAC), and a synchronous serial interface. Each of the

keypad controllers’ eight row and column inputs can be

reconfigured as general-purpose parallel I/O pins (GPIO).

All analog inputs are fully ESD protected, eliminating the

need for external TransZorb^™devices.

♦ ESD-Protected Analog Inputs

15kV IEC 1000-4-2 Air-Gap Discharge

8kV IEC 1000-4-2 Contact Discharge

♦ Single-Supply Operation

+2.7V to +3.6V (MAX1233)

+4.75V to +5.25V (MAX1234)

♦ 4-Wire Touch-Screen Interface

♦ Internal +1.0V/+2.5V Reference or External

Reference (+1.0V to AV

)

DD

♦ SPI^™/QSPI^™/MICROWIRE^™-Compatible 10MHz

Serial Interface

The MAX1233/MAX1234 offer programmable resolution

and sampling rates. Interrupts from the devices alert the

host processor when data is ready, when the screen is

touched, or a key press is detected. Software-

configurable scan control and internal timers give the user

flexibility without burdening the host processor. These

devices consume only 260µA at the maximum sampling

rate of 50ksps. Supply current falls to below 50µA for

sampling rates of 10ksps. The MAX1233/MAX1234 are

guaranteed over the -40°C to +85°C temperature range.

♦ 12-Bit, 50ksps ADC Measures

Resistive Touch-Screen Position and Pressure

Two Auxiliary Analog Inputs

Two Battery Voltages (0.5V to 6V)

On-Chip Temperature

♦ 8-Bit DAC for LCD Bias Control

♦ 4 × 4 Keypad Programmable Controller Offers Up

to Eight GPIO Pins

♦ Automatic Detection of Screen Touch, Key Press,

Applications

and End of Conversion

Personal Digital Assistants

♦ Programmable 8-, 10-, 12-Bit Resolution

♦ Programmable Conversion Rates

♦ AutoShutdown^™Between Conversions

Pagers

Touch-Screen Monitors

Cellular Phones

♦ Low Power

MP3 Players

260µA at 50ksps

50µA at 10ksps

6µA at 1ksps

Portable Instruments

Point-of-Sale Terminals

0.3µA Shutdown Current

-in Configuration

♦ 28-Pin 5mm × 5mm QFN and TQFN Packages

TOP VIEW

Ordering Information

PART

TEMP RANGE

PIN-PACKAGE

DV

AV

1

2

3

4

5

6

7

21 C4

20 C3

19 C2

18 C1

17 R1

16 R2

15 R3

DD

MAX1233EGI

MAX1233ETI

MAX1234EGI

MAX1234ETI

-40°C to +85°C 28 QFN (5mm x 5mm)

-40°C to +85°C 28 TQFN (5mm x 5mm)

-40°C to +85°C 28 QFN (5mm x 5mm)

-40°C to +85°C 28 TQFN (5mm x 5mm)

DD

*X+

*Y+

*X-

MAX1233

MAX1234

*Y-

GND

TransZorb is a trademark of General Semiconductor Industries, Inc.

SPI and QSPI are trademarks of Motorola, Inc.

QFN/TQFN

MICROWIRE is a trademark of National Semiconductor Corp.

AutoShutdown is a trademark of Maxim Integrated Products, Inc.

*PIN INCLUDES 8kV/15kV ESD PROTECTION.

________________________________________________________________ Maxim Integrated Products

1

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at

1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

1ꢀ5k ꢁEDꢂ-rotected TouchꢂEcreen

Controllers Include DAC and Keypad Controller

ABSOLUTE MAXIMUM RATINGS

AV

DV

to GND............................................................-0.3V to +6V

All Other Pins..................................................................... 2.5kV

Maximum Current into Any Pin............................................50mA

DD

to AV .......................................................-0.3V to +0.3V

DD

Digital Inputs/Outputs to GND.................-0.3V to (DV + 0.3V)

X+, Y+, X-, Y-, AUX1, AUX2,

Continuous Power Dissipation (T = +70°C)

DD

A

28-Pin QFN (derate 28.5mW/°C above +70°C) .................2W

28-Pin TQFN (derate 28.5mW/°C above +70°C) ...............2W

Operating Temperature Range ...........................-40°C to +85°C

Storage Temperature Range.............................-60°C to +150°C

Lead Temperature (soldering, 10s) .................................+300°C

and REF to GND ..................................-0.3V to (AV + 0.3V)

DD

BAT1, BAT2 to GND.................................................-0.3V to +6V

Maximum ESD per IEC 1000-4-2 (per MIL STD-883 HBM)

X+, X-, Y+, Y-, AUX1, AUX2, BAT1, BAT2...................... 15kV

Stresses beyond those listed under “Absolute Maximum Ratings” 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 operational sections of the specifications is not implied. Exposure to

absolute maximum rating conditions for extended periods may affect device reliability.

ELECTRICAL CHARACTERISTICS

(DV

= AV

= +2.7V to +3.6V (MAX1233), DV

= AV

= +4.75V to +5.25V (MAX1234), external reference V

= 2.5V

REF

DD

(MAX1233), V

= 4.096V (MAX1234); f

= 10MHz, f

= 50ksps, 12-bit mode, 0.1µF capacitor at REF, T = -40°C to

REF

SCLK

SAMPLE A

+85°C, unless otherwise noted. Typical values are at T = +25°C.)

A

PARAMETER

SYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

ANALOG-TO-DIGITAL CONVERTER

DC ACCURACY (Note 1)

Resolution

Software-programmable 8/10/12 bit

12

2

Bits

No Missing Codes

11

12-bit mode

0.8

0.5

0.8

0.5

2

Relative Accuracy (Note 2)

Differential Nonlinearity

Offset Error

INL

LSB

10-bit and 8-bit modes

12-bit mode

2

DNL

10-bit and 8-bit modes

12-bit mode

4

10-bit and 8-bit modes

12-bit mode

4

Gain Error (Note 3)

10-bit mode

LSB

8-bit mode

12-bit mode

Total Unadjusted Error

TUE

LSB

10-bit and 8-bit modes

1

Offset Temperature Coefficient

Gain Temperature Coefficient

Channel-to-Channel Offset

0.4

0.1

ppm/°C

LSB

Channel-to-Channel Gain

Matching

0.1

50

LSB

Noise

Including internal V

µV

RMS

REF

MAX1233

AV = DV

0.4

= +2.7V to +3.6V

= +5V 5%

DD

Full-scale

input

Power-Supply Rejection

PSR

mV

MAX1234

0.3

AV

= DV

DD

DYNAMIC SPECIFICATIONS (1kHz SINE WAVE, V = 2.5V

FOR MAX1233, V = 4.096V FOR MAX1234, 50ksps,

P-P

IN

P-P

IN

f

= 10MHz)

SCLK

Signal-to-Noise Plus Distortion

SINAD

69

dB

2

_______________________________________________________________________________________

1ꢀ5k ꢁEDꢂ-rotected TouchꢂEcreen

Controllers Include DAC and Keypad Controller

ELECTRICAL CHARACTERISTICS (continued)

(DV

= AV

= +2.7V to +3.6V (MAX1233), DV

= AV

= +4.75V to +5.25V (MAX1234), external reference V

= 2.5V

REF

DD

(MAX1233), V

= 4.096V (MAX1234); f

= 10MHz, f

= 50ksps, 12-bit mode, 0.1µF capacitor at REF, T = -40°C to

REF

SCLK

SAMPLE A

+85°C, unless otherwise noted. Typical values are at T = +25°C.)

A

PARAMETER

Total Harmonic Distortion

Spurious-Free Dynamic Range

Full-Power Bandwidth

Full-Linear Bandwidth

CONVERSION RATE

Internal Oscillator Frequency

Aperture Delay

SYMBOL

THD

CONDITIONS

MIN

TYP

-84

84

MAX

UNITS

dB

SFDR

dB

-3dB point

0.5

50

MHz

kHz

SINAD > 67dB

8

11.5

70

MHz

ns

30

Aperture Jitter

<50

ps

Maximum Serial Clock Frequency

Duty Cycle

f

10

30

MHz

%

SCLK

AUXILIARY ANALOG INPUTS (AUX1, AUX2)

Input Voltage Range

0

V

REF

1

Channel not selected or conversion

stopped

Input Leakage Current

0.1

34

µA

pF

Input Capacitance

BATTERY MONITOR INPUTS (BAT1, BAT2)

Input Voltage Range

0.5

6.0

V

Sampling battery

Battery monitor OFF

Internal reference

10

1

kΩ

GΩ

%

Input Impedance

Accuracy

-3

+3

TEMPERATURE MEASUREMENT

Temperature Range

-40

+85

°C

Differential method (Note 4)

1.6

0.3

3

Resolution

Single measurement method (Note 5)

Differential method (Note 4)

Accuracy

°C

Single measurement method (Note 5)

2

INTERNAL ADC REFERENCE

2.5V mode, T = +25°C

2.470

0.980

2.500

1.000

60

2.530

1.020

A

V

Reference Output Voltage

V

REF

1.0V mode, T = +25°C

A

Output Tempco

TCV

ppm/°C

Ω

REF

Reference Output Impedance

Reference Short-Circuit Current

Normal operation

250

18

mA

EXTERNAL ADC REFERENCE (INTERNAL REFERENCE DISABLED, REFERENCE APPLIED TO REF)

Reference Input Voltage Range

Input Impedance

(Note 6)

1.0

V

DD

CS = GND or V

1

GΩ

DD

V

= +2.5V at 50ksps (MAX1233)

= +4.096V at 50ksps (MAX1234)

5

10

15

REF

Input Current

µA

8

Shutdown/between conversions

0.1

_______________________________________________________________________________________

3

1ꢀ5k ꢁEDꢂ-rotected TouchꢂEcreen

Controllers Include DAC and Keypad Controller

ELECTRICAL CHARACTERISTICS (continued)

(DV

= AV

= +2.7V to +3.6V (MAX1233), DV

= AV

= +4.75V to +5.25V (MAX1234), external reference V

= 2.5V

REF

DD

(MAX1233), V

= 4.096V (MAX1234); f

= 10MHz, f

= 50ksps, 12-bit mode, 0.1µF capacitor at REF, T = -40°C to

SAMPLE A

REF

SCLK

+85°C, unless otherwise noted. Typical values are at T = +25°C.)

A

PARAMETER

SYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

DIGITAL-TO-ANALOG CONVERTER

DC ACCURACY

Resolution

8

Bits

LSB

mV

Integral Linearity Error

Differential Linearity Error

Offset Error

INL

(Note 7)

1.0

25

DNL

No missing codes

(Note 8)

V

1

OS

Offset Error Temperature

Coefficient

ppm/°C

%

Full-Scale Error

Code = 255, no load

5

Full-Scale Error Temperature

Coefficient

10

ppm/°C

DYNAMIC PERFORMANCE

Voltage Output Slew Rate

Output Settling Time

Glitch Impulse

Positive and negative

0.5LSB; 50kΩ and 50pF load (Note 9)

Code 127 to 128

0.4

20

40

50

V/µs

µs

nV/s

µs

Wake-Up Time

From shutdown

DAC OUTPUT

✕

0.85

0.9

0.95

Internal DAC Reference

V

(Note 10)

V

REFDAC

AV

DD

Code = 255; 0 to 100µA

Code = 0; 0 to 100µA

Power-down mode

TOUCH-SCREEN CONTROLLER

Y+, X+

0.5

Output Load Regulation

Output Resistance

LSB

0.5

1.0

MΩ

7

9

On-Resistance

Ω

Y-, X-

Touch-Detection Internal Pullup

Resistance

X+ to AV

1

MΩ

DD

KEYPAD CONTROLLER

C4, C3, C2, C1 (Note 11)

R4, R3, R2, R1 (Note 11)

DIGITAL INTERFACE

Pullup Resistance

0.5

16

kΩ

Pulldown Resistance

DIGITAL INPUTS (SCLK, CS, DIN, R_, C_)

✕

0.3

DV

Input Voltage Low

V

IL

DD

✕

0.7

DV

Input Voltage High

V

I

V

IH

DD

Input Leakage Current

0.1

1

µA

L

4

_______________________________________________________________________________________

1ꢀ5k ꢁEDꢂ-rotected TouchꢂEcreen

Controllers Include DAC and Keypad Controller

ELECTRICAL CHARACTERISTICS (continued)

(DV

= AV

= +2.7V to +3.6V (MAX1233), DV

= AV

= +4.75V to +5.25V (MAX1234), external reference V

= 2.5V

REF

DD

(MAX1233), V

= 4.096V (MAX1234); f

= 10MHz, f

= 50ksps, 12-bit mode, 0.1µF capacitor at REF, T = -40°C to

SAMPLE A

REF

SCLK

+85°C, unless otherwise noted. Typical values are at T = +25°C.)

A

PARAMETER

Input Capacitance

SYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

C

15

pF

IN

DIGITAL OUTPUT (DOUT)

I

= 2mA

= 4mA

0.4

0.8

SINK

Output Voltage Low

V

OL

DV

0.5

-

DD

Output Voltage High

V

I

= 1.5mA

SOURCE

OH

DIGITAL OUTPUT (BUSY, PENIRQ, KEYIRQ, R_, C_)

Output Voltage Low

V

I

= 0.2mA

0.4

V

OL

SINK

DV

0.5

DD

Output Voltage High

V

I

= 0.2mA

OH

SOURCE

POWER REQUIREMENTS

MAX1233

2.7

3

3.6

5.25

5

AV

DV

/

DD

Supply Voltage (Note 12)

V

DD

MAX1234

4.75

5

Idle; all blocks shut down

0.5

150

670

Only ADC on; f = 20ksps

SAMPLE

500

230

900

Analog and Digital Supply

Current

I

+

AVDD

µA

I

DVDD

Only DAC on; no load

Only internal reference on

TIMING CHARACTERISTICS

SCLK Clock Period

t

100

40

0

ns

CP

SCLK Pulse Width High

SCLK Pulse Width Low

DIN to SCLK Rise Setup

SCLK Rise to DIN Hold

SCLK Fall to DOUT Valid

CS Fall to DOUT Enabled

CS Rise to DOUT Disabled

CS Fall to SCLK Rise

t

CH

t

CL

DS

DH

t

C

= 50pF

40

45

40

DOV

LOAD

t

DV

t

DOD

t

40

0

CSS

CSH

GPO

CSW

CS Fall to SCLK Ignored

SCLK Rise to R_/C_ Data Valid

CS Pulse Width High

t

C

= 50pF (Note 13)

230

LOAD

t

40

Note 1: Tested at DV

= AV

= +2.7V (MAX1233), DV

= AV

= +5V (MAX1234).

DD

Note 2: Relative accuracy is the deviation of the analog value at any code from its theoretical value after the offset and gain errors

have been removed.

Note 3: Offset nulled.

Note 4: Difference between TEMP1 and TEMP2; temperature in °K = (V

Note 5: Temperature coefficient is -2.1mV/°C. Determine absolute temperature by extrapolating from a calibrated value.

- V

) × 2680°K/V. No calibration is necessary.

TEMP1

TEMP2

Note 6: ADC performance is limited by the conversion noise floor, typically 300µV . An external reference below 2.5V can

P-P

compromise the ADC performance.

Note 7: Guaranteed from code 5 to 255.

_______________________________________________________________________________________

5

1ꢀ5k ꢁEDꢂ-rotected TouchꢂEcreen

Controllers Include DAC and Keypad Controller

ELECTRICAL CHARACTERISTICS (continued)

(DV

= AV

= +2.7V to +3.6V (MAX1233), DV

= AV

= +4.75V to +5.25V (MAX1234), external reference V

= 2.5V

REF

DD

(MAX1233), V

= 4.096V (MAX1234); f

= 10MHz, f

= 50ksps, 12-bit mode, 0.1µF capacitor at REF, T = -40°C to

SAMPLE A

REF

SCLK

+85°C, unless otherwise noted. Typical values are at T = +25°C.)

A

Note 8: The offset value extrapolated from the range over which the INL is guaranteed.

Note 9: Output settling time is measured by stepping from code 5 to 255, and from code 255 to 5.

Note 10: Actual output voltage at full scale is 255/256 × V

.

REFDAC

Note 11: Resistance is open when configured as GPIO or in shutdown.

Note 12: AV and DV should not differ by more than 300mV.

DD

Note 13: When configured as GPIO.

Timing Diagram

CS

t

CSW

t

CSH

t

CP

t

CSH

t

CH

CSS

t

CL

CSS

SCLK

t

DH

t

DS

DIN

t

DOD

DOV

t

DV

DOUT

R_/C_

NOTE: TIMING NOT TO SCALE.

t

GPO

6

_______________________________________________________________________________________

1ꢀ5k ꢁEDꢂ-rotected TouchꢂEcreen

Controllers Include DAC and Keypad Controller

Typical Operating Characteristics

(AV

= DV

= 3V (MAX1233) or 5V (MAX1234), external V

= +2.5V (MAX1233), external V

= +4.096V (MAX1234), f

SCLK

=

DD

REF

10MHz (50% duty cycle), f

= 20ksps, C = 50pF, 0.1µF capacitor at REF, T = +25°C, unless otherwise noted.)

LOAD A

SAMPLE

SHUTDOWN CURRENT

vs. ANALOG SUPPLY VOLTAGE

SHUTDOWN CURRENT

vs. TEMPERATURE

INTERNAL OSCILLATOR FREQUENCY

vs. ANALOG SUPPLY VOLTAGE

300

250

200

150

100

50

300

250

200

150

100

50

10.0

9.8

9.6

9.4

9.2

9.0

8.8

8.6

8.4

8.2

8.0

MAX1233/MAX1234

0

2.7

3.2

3.7

4.2

4.7

5.2

-40

-20

0

20

40

60

80

2.7

3.2

3.7

4.2

4.7

5.2

AV (V)

DD

TEMPERATURE (°C)

AV (V)

DD

INTERNAL OSCILLATOR FREQUENCY

vs. TEMPERATURE

TEMP1 DIODE VOLTAGE

vs. ANALOG SUPPLY VOLTAGE

TEMP1 DIODE VOLTAGE

vs. TEMPERATURE

9.8

9.6

9.4

9.2

9.0

8.8

8.6

0.70

0.68

0.66

0.64

0.62

0.60

0.58

0.56

0.54

0.52

0.50

0.80

0.75

0.70

0.65

0.60

0.55

0.50

0.45

0.40

MAX1234, AV = +5.0V

DD

MAX1233, AV = +3.0V

DD

-40 -20

0

20

40

60

80

2.7

3.2

3.7

4.2

4.7

5.2

-40 -25 -10

5

20 35 50 65 80

TEMPERATURE (°C)

AV (V)

DD

TEMPERATURE (°C)

TEMP2 DIODE VOLTAGE

vs. ANALOG SUPPLY VOLTAGE

TEMP2 DIODE VOLTAGE

vs. TEMPERATURE

0.80

0.75

0.70

0.65

0.60

0.90

0.85

0.80

0.75

0.70

0.65

0.60

2.7

3.2

3.7

4.2

4.7

5.2

-40 -25 -10

5

20 35 50 65 80

AV (V)

DD

TEMPERATURE (°C)

_______________________________________________________________________________________

7

1ꢀ5k ꢁEDꢂ-rotected TouchꢂEcreen

Controllers Include DAC and Keypad Controller

Typical Operating Characteristics (continued)

(AV

= DV

= 3V (MAX1233) or 5V (MAX1234), external V

= +2.5V (MAX1233), external V

= +4.096V (MAX1234), f

=

DD

REF

SCLK

10MHz (50% duty cycle), f

= 20ksps, C = 50pF, 0.1µF capacitor at REF, T = +25°C, unless otherwise noted.)

LOAD A

SAMPLE

ADC INTEGRAL NONLINEARITY

vs. OUTPUT CODE

ADC DIFFERENTIAL NONLINEARITY

vs. OUTPUT CODE

1.0

0.8

0.6

0.4

0.2

0

1.0

0.8

0.6

0.4

0.2

0

-0.2

-0.4

-0.6

-0.8

-0.2

-0.4

-0.6

-0.8

-1.0

0

500 1000 1500 2000 2500 3000 3500 4000

OUTPUT CODE

0

500 1000 1500 2000 2500 3000 3500 4000

OUTPUT CODE

ADC OFFSET ERROR

vs. ANALOG SUPPLY VOLTAGE

ADC OFFSET ERROR vs. TEMPERATURE

2.0

1.5

1.0

0.5

0

2.0

1.5

1.0

0.5

0

-0.5

-1.0

-1.5

-0.5

-1.0

-1.5

-2.0

2.7

3.2

3.7

4.2

4.7

5.2

-40

-20

0

20

40

60

80

AV (V)

DD

TEMPERATURE (°C)

ADC GAIN ERROR

vs. TEMPERATURE

ADC GAIN ERROR

vs. ANALOG SUPPLY VOLTAGE

2.0

1.5

1.0

0.5

0

2.0

1.5

1.0

0.5

0

-0.5

-1.0

-1.5

-2.0

-0.5

-1.0

-1.5

-2.0

2.7

-40

-20

0

20

40

60

80

3.2

3.7

4.2

4.7

5.2

TEMPERATURE (°C)

AV (V)

DD

8

_______________________________________________________________________________________

1ꢀ5k ꢁEDꢂ-rotected TouchꢂEcreen

Controllers Include DAC and Keypad Controller

Typical Operating Characteristics (continued)

(AV

= DV

= 3V (MAX1233) or 5V (MAX1234), external V

= +2.5V (MAX1233), external V

= +4.096V (MAX1234), f

SCLK

=

DD

REF

10MHz (50% duty cycle), f

= 20ksps, C = 50pF, 0.1µF capacitor at REF, T = +25°C, unless otherwise noted.)

LOAD A

SAMPLE

ADC SUPPLY CURRENT

vs. SAMPLING RATE

ADC EXTERNAL REFERENCE INPUT

CURRENT vs. SAMPLING RATE

1000

100

10

8

MAX1233

= +2.5V

V

REF

6

4

2

0

1

0.1

1

10

100

1k

10k

100k

100

1k

10k

100k

f

(Hz)

SAMPLE

f

(Hz)

SAMPLE

ADC SUPPLY CURRENT

vs. TEMPERATURE

ADC SUPPLY CURRENT

vs. SUPPLY VOLTAGE

140

120

100

80

250

200

150

100

50

AV = +3V

DD

EXTERNAL REF

f

= 20ksps

SAMPLE

60

40

20

0

-40

-20

0

20

40

60

80

2.7

3.2

3.7

4.2

4.7

5.2

TEMPERATURE (°C)

AV (V)

DD

DAC DIFFERENTIAL NONLINEARITY

vs. OUTPUT CODE

DAC INTEGRAL NONLINEARITY vs. CODE

0.075

0.050

0.025

0

0.075

0.050

0.025

0

-0.025

-0.050

-0.075

-0.025

-0.500

-0.075

-0.100

0

50

100

150

200

250

300

250

150

0

50

100

200

300

OUTPUT CODE

CODE

_______________________________________________________________________________________

9

1ꢀ5k ꢁEDꢂ-rotected TouchꢂEcreen

Controllers Include DAC and Keypad Controller

Typical Operating Characteristics (continued)

(AV

= DV

= 3V (MAX1233) or 5V (MAX1234), external V

= +2.5V (MAX1233), external V

= +4.096V (MAX1234), f

=

DD

REF

SCLK

10MHz (50% duty cycle), f

= 20ksps, C = 50pF, 0.1µF capacitor at REF, T = +25°C, unless otherwise noted.)

LOAD A

SAMPLE

DAC FULL-SCALE ERROR

vs. ANALOG SUPPLY VOLTAGE

DAC FULL-SCALE ERROR

vs. TEMPERATURE

MAX1233/34 toc21

MAX1233/34 toc22

0.75

0.50

0.25

0

1.2

0.8

0.4

0

1.2

0.8

0.4

0

0.75

0.50

0.25

0

-0.25

-0.50

-0.4

-0.8

-0.4

-0.8

-0.25

-0.50

-0.75

-1.2

5.5

-1.2

-0.75

2.5

3.0

3.5

4.0

4.5

5.0

-40

-20

0

20

40

60

80

AV (V)

DD

TEMPERATURE (°C)

DAC SUPPLY CURRENT

vs. ANALOG SUPPLY VOLTAGE

DAC SUPPLY CURRENT

vs. TEMPERATURE

250

200

150

100

50

200

175

150

125

100

75

50

25

0

2.7

3.2

3.7

4.2

4.7

5.2

-40

-20

0

20

40

60

80

AV (V)

DD

TEMPERATURE (°C)

ADC REFERENCE VOLTAGE

vs. TEMPERATURE

ADC REFERENCE VOLTAGE

vs. ANALOG SUPPLY VOLTAGE

MAX1233/34 toc26

MAX1233/34 toc25

2.60

2.55

2.50

2.45

2.40

1.250

1.125

1.000

0.875

0.750

2.550

2.525

2.500

2.475

2.450

1.020

1.010

1.000

0.990

0.980

V

= 1.0V

REF

V

= 1.0V

= 2.5V

REF

V

REF

V

= 2.5V

2.7

3.2

3.7

4.2

4.7

5.2

-40

-20

0

20

40

60

80

TEMPERATURE (°C)

AV (V)

DD

10 ______________________________________________________________________________________

1ꢀ5k ꢁEDꢂ-rotected TouchꢂEcreen

Controllers Include DAC and Keypad Controller

Typical Operating Characteristics (continued)

(AV

= DV

= 3V (MAX1233) or 5V (MAX1234), external V

= +2.5V (MAX1233), external V

= +4.096V (MAX1234), f

=

DD

REF

SCLK

10MHz (50% duty cycle), f

= 20ksps, C = 50pF, 0.1µF capacitor at REF, T = +25°C, unless otherwise noted.)

LOAD A

SAMPLE

ADC REFERENCE SUPPLY CURRENT

vs. ANALOG SUPPLY VOLTAGE

REFERENCE SUPPLY CURRENT

vs. TEMPERATURE

750

700

650

600

750

700

650

600

550

2.7

3.2

3.7

4.2

4.7

5.2

-40 -25 -10

5

20 35 50 65 80

AV (V)

DD

TEMPERATURE (°C)

-in Description

NAME

FUNCTION

Positive Digital Supply Voltage, +2.7V to +3.6V for MAX1233, +4.75V to +5.25V for MAX1234. Bypass

with a 0.1µF capacitor. Must be within 300mV of AV

1

DV

DD

.

DD

Positive Analog Supply Voltage, +2.7V to +3.6V for MAX1233, +4.75V to +5.25V for MAX1234.

2

AV

Bypass with a 0.1µF capacitor. Must be within 300mV of DV

.

DD

3*

4*

X+

X+ Position Input

Y+

X-

Y+ Position Input

5*

X- Position Input

6*

Y-

Y- Position Input

7

GND

BAT1

BAT2

AUX1

AUX2

Analog and Digital Ground

8*

Battery Monitoring Input 1. Measures battery voltages up to 6V.

Battery Monitoring Input 2. Measures battery voltages up to 6V.

Auxiliary Analog Input 1 to ADC. Measures analog voltages from zero to V

Auxiliary Analog Input 2 to ADC. Measures analog voltages from zero to V

9*

10*

11*

.

REF

.

REF

Voltage Reference Output/Input. Reference voltage for analog-to-digital conversion. In internal

reference mode, the reference buffer provides a 2.5V or 1.0V nominal output. In external reference

mode, apply a reference voltage between 1.0V and AV . Bypass REF to GND with a 0.1µF

DD

12

REF

capacitor in the external reference mode only.

13

14

15

16

17

18

DACOUT

R4

DAC Voltage Output; 0.9 × AV

Full Scale

DD

Keypad Row 4. Can be reconfigured as GPIO3.

Keypad Row 3. Can be reconfigured as GPIO2.

Keypad Row 2. Can be reconfigured as GPIO1.

Keypad Row 1. Can be reconfigured as GPIO0.

Keypad Column 1. Can be reconfigured as GPIO4.

R3

R2

R1

C1

______________________________________________________________________________________ 11

1ꢀ5k ꢁEDꢂ-rotected TouchꢂEcreen

Controllers Include DAC and Keypad Controller

-in Description (continued)

19

20

21

22

23

24

NAME

C2

FUNCTION

Keypad Column 2. Can be reconfigured as GPIO5.

C3

Keypad Column 3. Can be reconfigured as GPIO6.

C4

Keypad Column 4. Can be reconfigured as GPIO7.

KEYIRQ

PENIRQ

DOUT

Active-Low Keypad Interrupt. KEYIRQ is low when a key press is detected.

Active-Low Pen Touch Interrupt. PENIRQ is low when a screen touch is detected.

Serial Data Output. Data is clocked out at SCLK falling edge. High impedance when CS is high.

Active-Low Busy Output. BUSY goes low and stays low during each functional operation. The host

controller should wait until BUSY is high again before using the serial interface.

25

26

27

BUSY

DIN

Serial Data Input. Data is clocked in on the rising edge of SCLK.

Serial Clock Input. Clocks data in and out of the serial interface and sets the conversion speed (duty

cycle must be 30% to 70%).

SCLK

Active-Low Chip Select. Data is not clocked into DIN unless CS is low. When CS is high, DOUT is

high impedance.

28

CS

*ESD protected: 8kꢀ Contact, 15kꢀ Air.

open or floating. The point where the touch screen is

pressed brings the two resistive layers in contact and

creates a voltage-divider at that point. The data convert-

er senses the voltage at the point of contact through the

X+ input and digitizes it.

Detailed Description

The MAX1233/MAX1234 are 4-wire touch-screen con-

trollers. Figure 1 shows the functional diagram of the

MAX1233/MAX1234. Each device includes a 12-bit sam-

pling ADC, 8-bit voltage output DAC, keypad scanner

that can also be configured as a GPIO, internal clock,

reference, temperature sensor, two battery monitor

inputs, two auxiliary analog inputs, SPI/QSPI/

MICROWIRE-compatible serial interface, and low on-

resistance switches for driving touch screens.

12ꢂBit ADC

Analog Inputs

Figure 3 shows a block diagram of the ADC’s analog

input section including the input multiplexer, the differen-

tial input, and the differential reference. The input multi-

plexer switches between X+, X-, Y+, Y-, AUX1, AUX2,

BAT1, BAT2, and the internal temperature sensor.

The 16-bit register inside the MAX1233/MAX1234

allows for easy control and stores results that can be

read at any time. The BUSY output indicates that a

functional operation is in progress. The PENIRQ and

KEYIRQ outputs, respectively, indicate that a screen

touch or a key press has occurred.

The time required for the T/H to acquire an input signal

is a function of how quickly its input capacitance is

charged. If the input signal’s source impedance is high,

the acquisition time lengthens, and more time must be

allowed. The acquisition time (t

) is the maximum

ACQ

TouchꢂEcreen Operation

The 4-wire touch-screen controller works by creating a

voltage gradient across the vertical or horizontal resis-

tive touch screen connected to the analog inputs of the

MAX1233/MAX1234, as shown in Figure 2. The voltage

across the touch-screen panels is applied through inter-

nal MOSFET switches that connect each resistive layer

time the device takes to acquire the input signal to 12-

bit accuracy. Configure t by writing to the ADC

ACQ

control register. See Table 1 for the maximum input sig-

nal source impedance (R

during acquisition.

) for complete settling

SOURCE

Accommodate higher source impedances by placing a

0.1µF capacitor between the analog input and GND.

to AV

and ground. For example, to measure the Y

DD

position when a pointing device presses on the touch

screen, the Y+ and Y- drivers are turned on, connecting

Input Bandwidth

The ADC’s input-tracking circuitry has a 0.5MHz small-

signal bandwidth. To avoid high-frequency signals

being aliased into the frequency band of interest, anti-

alias filtering is recommended.

one side of the vertical resistive layer to AV

and the

DD

other side to ground. The horizontal resistive layer func-

tions as a sense line. One side of this resistive layer gets

connected to the X+ input, while the other side is left

12 ______________________________________________________________________________________

1ꢀ5k ꢁEDꢂ-rotected TouchꢂEcreen

Controllers Include DAC and Keypad Controller

C1 C2 C3 C4 R1 R2

R3 R4

KEYPAD CONTROLLER

AND GPIO

OSCILLATOR

MAX1233

MAX1234

REGISTERS AND

SCAN STATE

CONTROL

TEMP

SENSOR

DOUT

SCLK

DIN

*X+

*X-

X/Y SWITCHES

SERIAL

DATA

I/O

*Y+

*Y-

MUX

CS

12-BIT

ADC

PENIRQ

KEYIRQ

*BAT1

*BAT2

BATTERY MONITOR

BUSY

*AUX1

*AUX2

INTERNAL

REFERENCE

2.5V/1.0V

REF

8-BIT

DAC

DACOUT

REF

DAC

*ESD PROTECTED

Figure 1. Block Diagram

Table 1. Maximum Input Source

Impedance

+AV

DD

FORCE LINE

MAXIMUM R

COMPLETE SETTLING

DURING ACQUISITION (kΩ)

FOR

SOURCE

ACQUISITION RESOLUTION

Y+

X+

Y-

TIME (µs)

(BITS)

1.5

5.0

95

8

2.6

2.0

1.5

23

10

12

8

SENSE LINE

+REF

-REF

+IN

-IN

SENSE

LINE

10

12

8

19

15

560

470

400

FORCE LINE

95

10

12

GND

95

Figure 2. Touch-Screen Measurement

______________________________________________________________________________________ 13

1ꢀ5k ꢁEDꢂ-rotected TouchꢂEcreen

Controllers Include DAC and Keypad Controller

+AV

DD

V

REF

TEMP2

TEMP1

MAX1233

MAX1234

X+

X-

REF ON/OFF

+REF

Y+

Y-

+IN

-IN

CONVERTER

2.5V/1.0V

REFERENCE

-

REF

7.5kΩ

V

BAT1

BAT2

2.5kΩ

BATTERY

ON

BATTERY

ON

AUX1

AUX2

GND

Figure 3. Simplified Diagram of Analog Input Section

Analog Input Protection

to 8kV, using the Contact-Discharge method and

15kV using the Air-Gap method specified in IEC-

1000-4-2.

Internal protection diodes that clamp the analog input

to AV

and GND allow the analog input pins to swing

DD

from GND - 0.3V to AV

+ 0.3V without damage.

DD

Reference for ADC

Analog inputs must not exceed AV

by more than

DD

Internal Reference

The MAX1233/MAX1234 offer an internal voltage refer-

ence for the ADC that can be set to +1.0V or +2.5V. The

MAX1233/MAX1234 typically use the internal reference

for battery monitoring, temperature measurement, and for

50mV or be lower than GND by more than 50mV for

accurate conversions. If an off-channel analog input

voltage exceeds the supplies, limit the input current to

50mA. All analog inputs are also fully ESD protected

14 ______________________________________________________________________________________

1ꢀ5k ꢁEDꢂ-rotected TouchꢂEcreen

Controllers Include DAC and Keypad Controller

ment, temperature measurement, or auxiliary input

measurement is written to the ADC control register, the

device powers on the internal reference, waits for the

internal reference to settle, completes the requested

+1.25V

BANDGAP

scan, and powers down the internal reference. The ref-

erence power delay depends upon the ADC resolution

REF PIN

3R

2R

2x

selected (see Table 8). Do not bypass REF with an

external capacitor when performing scans in auto

power-down mode.

OPTIONAL

Full-Power Mode (RES1 = 0, RES0 = 1)

In the full-power mode, the RES1 bit is set LOW and

RES0 bit is set HIGH. In this mode, the device is pow-

ered up and the internal ADC reference is always ON.

The MAX1233/MAX1234 internal reference remains fully

powered after completing a scan.

Figure 4. Block Diagram of the Internal Reference

Internal Cloc5

The MAX1233/MAX1234 operate from an internal oscil-

lator, which is accurate to within 20% of the 10MHz

specified clock rate. The internal oscillator controls the

timing of the acquisition, conversion, touch-screen set-

tling, reference power-up, and keypad debounce times.

measurement of the auxiliary inputs. Figure 4 shows the

on-chip reference circuitry of the MAX1233/MAX1234.

Set the internal reference voltage by writing to the RFV

bits in the ADC control register (see Tables 4, 5, and 12).

The MAX1233/MAX1234 can accept an external refer-

ence connected to REF for ADC conversion.

8ꢂBit DAC

The MAX1233/MAX1234 have a voltage-output, true 8-bit

monotonic DAC with less than 1LSB integral nonlinearity

error and less than 1LSB differential nonlinearity error. It

requires a supply current of only 150µA (typ) and pro-

vides a buffered voltage output. The DAC is at midscale

code at power-up and remains there until a new code is

written to the DAC register. During shutdown, the DAC’s

output is pulled to ground with a 1MΩ load.

The internal DAC can be used in various system applica-

tions such as LCD/TFT-bias control, automatic tuning

(VCO), power amplifier bias control, programmable

threshold levels, and automatic gain control (AGC).

External Reference

The MAX1233/MAX1234 can accept an external refer-

ence connected to the REF pin for ADC conversions.

The internal reference should be disabled (RES1 = 1)

when using an external reference. At a conversion rate

of 50ksps, an external reference at REF must deliver up

to 15µA of load current and have 50Ω or less output

impedance. If the external reference has high output

impedance or is noisy, bypass it close to the REF pin

with a 0.1µF capacitor.

Selecting Internal or External Reference

Set the type of reference being used by programming

the ADC control register. To select the internal refer-

ence, clock zeros into bits [A/D3:A/D0] and a zero to bit

RES1, as shown in the Control Registers section. To

change to external reference mode, clock zeros into

bits [A/D3:A/D0] and a one to bit RES1. See Table 13

for more information about selecting an internal or

external reference for the ADC.

The 8-bit DAC in the MAX1233/MAX1234 employs a

current-steering topology as shown in Figure 5. At the

core of this DAC is a reference voltage-to-current con-

verter (V/I) that generates a reference current. This cur-

rent is mirrored to 255 equally weighted current

sources. DAC switches control the outputs of these cur-

rent mirrors so that only the desired fraction of the total

current-mirror currents is steered to the DAC output.

The current is then converted to a voltage across a

resistor, and the output amplifier buffers this voltage.

Reference -ower Modes

Auto Power-Down Mode (RES1 = RES0 = 0)

The MAX1233/MAX1234 are in auto power-down mode

at initial power-up. Set the RES1 and RES0 bits to zero

to use the MAX1233/MAX1234 in the auto power-down

mode. In this mode, the internal reference is normally

off. When a command to perform a battery measure-

DAC Output Voltage

The 8-bit DAC code is binary unipolar with 1LSB =

(V

/256). The DAC has a full-scale output voltage of

REF

(0.9 × AV

- 1LSB).

DD

______________________________________________________________________________________ 15

1ꢀ5k ꢁEDꢂ-rotected TouchꢂEcreen

Controllers Include DAC and Keypad Controller

+AV

DD

V

REF

1MΩ

SW255

SW1

SW2

S1

TOUCH-SCREEN

DETECTOR

PENIRQ

TOUCH

OUT

X+

Y+

SCREEN

Figure 5. DAC Current-Steering Topology

X-

Y-

Output Buffer

The DAC voltage output is an internally buffered unity-

gain follower that slews at up to 0.4V/µs. The output

can swing from zero to full scale. With a 1/4FS to 3/4FS

output transition, the amplifier output typically settles to

1/2LSB in less than 5µs when loaded with 10kΩ in par-

allel with 50pF. The buffer amplifier is stable with any

combination of resistive loads >10kΩ and capacitive

loads <50pF.

S2

Power-On Reset

All registers of the MAX1233/MAX1234 power up at a

default zero state, except the DAC data register, which

is set to 10000000, so the output is at midscale.

Figure 6. Touch-Screen Detection Block Diagram

shown in Figure 6. When the screen is touched, the X+

pin is pulled to GND through the touch screen and a

touch is detected.

Keypad Controller and G-IO

The keypad controller is designed to interface a matrix-

type 4 rows × 4 columns (16 keys or fewer) keypad to a

host controller. The KEY control register controls keypad

interrupt, keypad scan, and keypad debounce times.

The KeyMask and ColumnMask registers enable mask-

ing of a particular key or an entire column of the keypad

when they are not in use. The MAX1233/MAX1234 offer

two keypad data registers. KPData1 is the pending reg-

ister. KPData2 holds keypad scan results of only the

unmasked keys. If 12 or fewer keys are being monitored,

one or more of the row/column pins of the

MAX1233/MAX1234 can be software programmed as

GPIO pins.

When the 1MΩ pullup resistor is first connected, the X+

pin can be floating near ground. To prevent false touch

detection in this case, the X+ pin is precharged high for

0.1µs using the 7Ω PMOS driver before touch detection

begins.

Keyꢂ-ress Detection

Key-press detection can be enabled or disabled by

writing to the keypad control register as shown in Table

17. Key-press detection is disabled at initial power-up.

Once key-press detection is enabled, the C_ pins are

internally connected to DV

and the R_ pins are inter-

DD

nally pulled to GND through a 16kΩ resistor. When a

key is pressed, the associated row pin is pulled to

DV

and the key press is detected. Figure 7 shows

DD

TouchꢂEcreen Detection

Touch-screen detection can be enabled or disabled by

writing to the ADC control register as shown in Table 4.

Touch-screen detection is disabled at initial power-up.

Once touch-screen detection is enabled, the Y- driver

is on and the Y- pin is connected to GND. The X+ pin is

the key-press detection circuitry.

Interrupts

PEN Interrupt Request (PENIRQ)

The PENIRQ output can be used to alert the host con-

troller of a screen touch. The PENIRQ output is normally

high and goes low after a screen touch is detected.

internally pulled to AV

through a 1MΩ resistor as

DD

16 ______________________________________________________________________________________

1ꢀ5k ꢁEDꢂ-rotected TouchꢂEcreen

Controllers Include DAC and Keypad Controller

SIMPLIFIED KEYPAD CIRCUITRY

DRIVERS PULL HIGH

OR GO THREE-STATE

C1

C2

C3

C4

R1

R2

R3

R4

TO KEYPAD

WAKEUP AND

DEBOUNCE

LOGIC

KEYPAD

Figure 7. Key-Press Detection Circuitry

X+

PENIRQ

BUSY

CS

DATA

READ

DIN

DATA

READ

DOUT

TOUCH-

SCREEN

DATA

DOUT

TOUCH-

SCREEN

DATA

Figure 8a. Timing Diagram for Touch-Initiated Screen Scan

Figure 8b. Timing Diagram for Host-Initiated Screen Scan

______________________________________________________________________________________ 17

1ꢀ5k ꢁEDꢂ-rotected TouchꢂEcreen

Controllers Include DAC and Keypad Controller

PENIRQ returns high only after a touch-screen scan is

completed. PENIRQ does not go low again until one of

R_

the touch-screen data registers is read. Figures 8a and

8b show the timing diagrams for the PENIRQ pin.

KEYIRQ

Keypad Interrupt Request (KEYIRQ)

The KEYIRQ output can be used to alert the host con-

troller of a key press. The KEYIRQ output is normally

high and goes low after a key press is detected.

BUSY

KEYIRQ returns high only after a key-press scan is

completed. KEYIRQ does not go low again until one of

the key-press data registers is read. Figures 9a and 9b

CS

show the timing diagrams for the KEYIRQ pin.

DATA

READ

Busy Indicator (BUSY)

BUSY informs the host processor that a scan is in

progress. BUSY is normally high and goes low and

stays low during each functional operation. The host

controller should wait until BUSY is high again before

using the serial interface.

DOUT

TOUCH-

SCREEN

DATA

Figure 9a. Timing Diagram for Key-Press-Initiated Debounce

Scan

Digital Interface

The MAX1233/MAX1234 interface to the host controller

through a standard 3-wire serial interface at up to

10MHz. DIN and CS are the digital inputs to the

MAX1233/MAX1234. DOUT is the serial data output.

Data is clocked out at the SCLK falling edge and is high

impedance when CS is high. PENIRQ and KEYIRQ com-

municate interrupts from the touch-screen and keypad

controllers to the host processor when a screen touch or

a key press is detected. BUSY informs the host proces-

sor that a scan is in progress. In addition to these digital

I/Os, the row and column pins of the keypad controller

can be programmed as GPIO pins.

R_

KEYIRQ

BUSY

CS

DATA

READ

DIN

Communications Protocol

The MAX1233/MAX1234 are controlled by reading from

and writing to registers through the 3-wire serial inter-

face. These registers are addressed through a 16-bit

command that is sent prior to the data. The command

is shown in Table 2.

DOUT

TOUCH-

SCREEN

DATA

Figure 9b. Timing Diagram for Host-Initiated Keypad

Debounce Scan

The first 16 bits after the falling edge of CS contain the

command word. The command word begins with an

R/W bit, which specifies the direction of data flow on

the serial bus. Bits 14 through 7 are reserved for future

use. Bit 6 specifies the page of memory in which the

desired register is located. The last 6 bits specify the

address of the desired register. The next 16 bits of data

are read from or written to the address specified in the

command word. After 32 clock cycles, the interface

automatically increments its address pointer and con-

tinues reading or writing until the rising edge of CS, or

until it reaches the end of the page.

Table 2. Command Word Format

BIT15

MSB

BIT0

BIT14 BIT13 BIT12 BIT11 BIT10 BIT9

RES RES RES RES RES RES

BIT8

BIT7

BIT6

BIT5

BIT4

BIT3

BIT2

BIT1

LSB

RES PAGE ADD5 ADD4 ADD3 ADD2 ADD1 ADD0

R/W

RES

18 ______________________________________________________________________________________

1ꢀ5k ꢁEDꢂ-rotected TouchꢂEcreen

Controllers Include DAC and Keypad Controller

Table 3. Register Summary for MAX1233/MAX1234

ADDR

(HEX)

00

01

02

03

04

05

06

07

08

09

0A

0B

0C

0D

0E

0F

10

11

12

13

14

15

16

17

18

19

1A

1B

1C

1D

1E

1F

00

01

02

03

04

05

06

07

08

09

0A

0B

0C

0D

0E

REGISTER

PAGE

BIT15

BIT14

BIT13 BIT12 BIT11

BIT10

BIT9

BIT8

BIT7

BIT6

BIT5

BIT4

BIT3

BIT2

BIT1

BIT0

NAME

0

1

X

Y

Z1

Z2

KPD

BAT1

BAT2

AUX1

0

K15

0

GPD7

K1_15

K2_15

0

RES

0

K14

0

X11

Y11

X10

Y10

X9

Y9

X8

Y8

X7

Y7

X6

Y6

X5

Y5

X4

Y4

X3

Y3

X2

Y2

X1

Y1

X0

Y0

0

Z1_11 Z1_10 Z1_9

Z2_11 Z2_10 Z2_9

Z1_8 Z1_7 Z1_6 Z1_5 Z1_4 Z1_3 Z1_2 Z1_1 Z1_0

Z2_8 Z2_7 Z2_6 Z2_5 Z2_4 Z2_3 Z2_2 Z2_1 Z2_0

K8

K13

0

K12

0

K11

K10

K9

K7

K6

K5

K4

K3

K2

K1

K0

B1_11 B1_10 B1_9 B1_8 B1_7 B1_6 B1_5 B1_4 B1_3 B1_2 B1_1 B1_0

B2_11 B2_10 B2_9 B2_8 B2_7 B2_6 B2_5 B2_4 B2_3 B2_2 B2_1 B2_0

A1_11 A1_10 A1_9 A1_8 A1_7 A1_6 A1_5 A1_4 A1_3 A1_2 A1_1 A1_0

A2_11 A2_10 A2_9 A2_8 A2_7 A2_6 A2_5 A2_4 A2_3 A2_2 A2_1 A2_0

AUX2

TEMP1

TEMP2

DAC

Reserved

GPIO

KPData1

KPData2

Reserved

ADC

0

T1_11 T1_10 T1_9

T2_11 T2_10 T2_9

T1_8 T1_7 T1_6 T1_5 T1_4 T1_3 T1_2 T1_1 T1_0

T2_8 T2_7 T2_6 T2_5 T2_4 T2_3 T2_2 T2_1 T2_0

0

DA7

DA6

DA5

DA4

DA3

DA2

DA1

DA0

0

GPD6

GPD5 GPD4 GPD3 GPD2 GPD1 GPD0

K1_14 K1_1 K1_1 K1_11 K1_10 K1_9 K1_8 K1_7 K1_6 K1_5 K1_4 K1_3 K1_2 K1_1 K1_0

K2_14 K2_1 K2_1 K2_11 K2_10 K2_9 K2_8 K2_7 K2_6 K2_5 K2_4 K2_3 K2_2 K2_1 K2_0

0

RES

ST1

0

RES

ST0

0

RES

RFV

0

RES

ADSTS

RES

PENSTS

A/D3 A/D2 A/D1 A/D0 RES1 RES0 AVG1 AVG2 CNR1 CNR0 ST2

KEY

DAC

KEYSTS1 KEYSTS0 DBN2 DBN1 DBN0 HLD2 HLD1 HLD0

DAPD

0

PU6

0

PU2

0

PU1

0

PU0

Reserved

0

PU7

0

Reserved

GPIO

Pullup

0

PU5

PU4

PU3

1

0F

10

11

GPIO

GP7

KM15

CM4

GP6

KM14

CM3

GP5

GP4

GP3

GP2

GP1

GP0

KM8

0

OE7

KM7

0

OE6

KM6

0

OE5

KM5

0

OE4

KM4

0

OE3

KM3

0

OE2

KM2

0

OE1

KM1

0

OE0

KM0

0

KPKeyMask

KPColumn

Mask

KM13 KM12 KM11 KM10 KM9

CM2 CM1

0

1

12

13

14

15

16

17

18

19

1A

1B

1C

1D

1E

1F

Reserved

0

______________________________________________________________________________________ 19

1ꢀ5k ꢁEDꢂ-rotected TouchꢂEcreen

Controllers Include DAC and Keypad Controller

In order to read the entire first page of memory, for

example, the host processor must send the

Memory Map

The MAX1233/MAX1234s’ internal memory is divided

into two pages—one for data and one for control, each

of which contains thirty-two 16-bit registers.

MAX1233/MAX1234 the command 0x8000 . The

H

MAX1233/MAX1234 then begin clocking out 16-bit data

starting with the X-data register. In order to write to the

second page of memory, the host processor sends the

Control Registers

Table 3 provides a summary of all registers and bit

locations of the MAX1233/MAX1234.

MAX1233/MAX1234 the command 0x0040 . The suc-

H

ceeding data is then written in 16-bit words beginning

with the ADC control register. Figures 10a and 10b show

a complete write and read operation, respectively,

between the processor and the MAX1233/MAX1234.

ADC Control Register

The ADC measures touch position, touch pressure, bat-

tery voltage, auxiliary analog inputs, and temperature.

The ADC control register determines which input is

selected and converted. Tables 4 and 5 show the for-

mat and bit descriptions for the ADC control register.

SCLK

WRITE OPERATION

CS

D0

DIN

D15

D15 IS READ/WRITE BIT

LOW FOR WRITE

D15–D0 COMMAND WORD

D15–D0 DATA WORD

THREE-

STATE

DOUT

THREE-

STATE

TIMING NOT TO SCALE.

Figure 10a. Timing Diagram of Write Operation

SCLK

READ OPERATION

CS

DIN

D15 D14

D0

D15–D0 COMMAND

WORD

DOUT

THREE-STATE

D0

D15

D0

THREE-STATE

DATA WORD

Figure 10b. Timing Diagram of Read Operation

Table 4. ADC Control Register

BIT15

BIT14 BIT13 BIT12 BIT11 BIT10 BIT9 BIT8 BIT7 BIT6 BIT5 BIT4 BIT3 BIT2 BIT1 BIT0

ST1 ST0 RFV

PENSTS ADSTS A/D3 A/D2 A/D1 A/D0 RES1 RES0 AVG1 AVG0 CNR1 CNR0 ST2

20 ______________________________________________________________________________________

1ꢀ5k ꢁEDꢂ-rotected TouchꢂEcreen

Controllers Include DAC and Keypad Controller

Bits 14-15: Pen Interrupt Status and

ADC Status Bits

Bits 6-7: Converter Averaging Control

These bits specify the number of data averages the

converter performs. Table 9 shows how to program for

the desired number of averages. When averaging is

used, ADSTS and BUSY indicate the converter is busy

until all conversions needed for the averaging finish.

These bits are identical, regardless of read or write.

These bits are used to control or monitor ADC scans.

Bits 10-13: ADC Scan Select

These bits control which input to convert and which con-

verter mode is used. The bits are identical regardless of a

read or write. See Table 7 for details about using these bits.

Bits 4-5: ADC Conversion Rate Control

These bits specify the internal conversion rate, which

the ADC uses to perform a single conversion, as shown

in Table 10. Lowering the conversion rate also reduces

power consumption. These bits are identical, regard-

less of read or write.

Bits 8-9: ADC Resolution Control

These bits specify the ADC resolution and are identical

regardless of read or write. Table 8 shows how to use

these bits to set the resolution.

Table 5. ADC Control Register Bit Descriptions

BIT

NAME

PENSTS

ADSTS

A/D3

DESCRIPTION

15 (MSB)

Read: pen interrupt status; Write: sets interrupt initiated touch-screen scans

14

Read: ADC status; Write: stops ADC

Selects ADC scan functions

13

12

A/D2

Selects ADC scan functions

11

A/D1

Selects ADC scan functions

10

A/D0

Selects ADC scan functions

9

RES1

RES0

AVG1

AVG0

CNR1

CNR0

ST2

Controls ADC resolution

8

Controls ADC resolution

7

Controls ADC result averaging

Controls ADC conversion rate

Controls touch-screen settling wait time

Chooses 1.0V or 2.5V reference

6

5

4

3

2

1

ST1

ST0

0 (LSB)

RFV

Table 6. ADSTS Bit Operation

PENSTS

ADSTS

READ FUNCTION

WRITE FUNCTION

Performs one scan and waits to detect a screen touch. Upon

detection, issues an interrupt and waits until told to scan by the

host controller.

No screen touch detected;

scan or conversion in progress

0

Screen touch detected;

scan or conversion in progress detection, issues an interrupt and performs a scan.

Stops any ongoing scan and waits to detect a screen touch. Upon

1

0

1

0

1

Stops any ongoing scan and waits to detect a screen touch. Upon

detection, issues an interrupt and waits until told to scan by the

host controller.

No screen touch detected;

data available

Screen touch detected;

data available

Stops any ongoing scan and powers down the screen touch

detection circuit. No screen touches are detected in this mode.

______________________________________________________________________________________ 21

1ꢀ5k ꢁEDꢂ-rotected TouchꢂEcreen

Controllers Include DAC and Keypad Controller

Table 7. ADC Scan Select (Touch Screen, Battery, Auxiliary Channels, and Temperature)

A/D3 A/D2 A/D1 A/D0

FUNCTION

Configures the ADC reference as selected by RES [1:0] bits as shown in Table 13. No measurement

is performed.

0

1

0

1

0

Measures X/Y touch position and returns results to the X and Y data registers.

Measures X/Y touch position and Z1/ Z2 touch pressure and returns results to the X, Y, Z1, and Z2

data registers.

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

Measures X touch position and returns results to the X data register.

Measures Y touch position and returns results to the Y data register.

Measures Z1/Z2 touch pressure and returns results to the Z1 and Z2 data register.

Measures Battery Input 1 and returns results to the BAT1 data register.

Measures Battery Input 2 and returns results to the BAT2 data register.

Measures Auxiliary Input 1 and returns results to the AUX1 data register.

Measures Auxiliary Input 2 and returns results to the AUX2 data register.

Measures temperature (single ended) and returns results to the TEMP1 data register.

Measures Battery Input 1, Battery Input 2, Auxiliary Input 1, Auxiliary Input 2, and temperature

(differential), and returns results to the appropriate data registers.

1

0

1

0

1

0

1

0

1

Measures temperature (differential) and returns results to the TEMP1 and TEMP2 data registers.

Turns on Y+, Y- drivers. No measurement is performed.

Turns on X+, X- drivers. No measurement is performed.

Turns on Y+, X- drivers. No measurement is performed.

Table 10. ADC Conversion Rate Control

Table 8. ADC Resolution Control

CNR1 CNR0

FUNCTION

INTERNALLY TIMED

REFERENCE POWER-UP

DELAY* (µs)

ADC

RESOLUTION

RES1 RES0

3.5µs/sample

0

1

0

1

0

1

(1.5µs acquisition, 2µs conversion)

0

1

0

1

0

1

8 bit

31

37

44

3.5µs/sample

(1.5µs acquisition, 2µs conversion)

10 bit

12 bit

10µs/sample

(5µs acquisition, 5µs conversion)

*Applicable only for temperature, battery, or auxiliary

measurements in auto power-up reference mode.

100µs/sample

(95µs acquisition, 5µs conversion)

Table 9. ADC Averaging Control

AVG1 AVG0

FUNCTION

No data averages (default)

4 data averages

0

1

0

1

0

1

8 data averages

16 data averages

22 ______________________________________________________________________________________

1ꢀ5k ꢁEDꢂ-rotected TouchꢂEcreen

Controllers Include DAC and Keypad Controller

Bits 1-3: Touch-Screen Settling Time Control

These bits specify the time delay from pen-touch detec-

tion to a conversion start. This allows the selection of the

appropriate settling time for the touch screen being used.

Table 11 shows how to set the settling time. These bits

are identical, regardless of read or write.

Internal ADC Reference Power-Down Control

The ADC control register controls the power setting of

the internal ADC reference. Zeros must be written to

bits A/D3–A/D0 to control internal reference power-up

followed by the appropriate logic at the RES1 and

RES0 bits. Table 13 shows the internal ADC reference

power-down control.

Bit 0: ADC Internal Reference Voltage Control

This bit selects the ADC internal reference voltage,

either +1.0V or +2.5V. This bit is identical, regardless of

read or write. The reference control bit is shown in

Table 12.

DAC Control Register

The MSB in this control register determines the power-

down control of the on-board DAC. Table 14 shows the

DAC control register. Writing a zero to bit 15 (DAPD)

powers up the DAC, while writing a 1 powers down the

DAC. Table 15 describes the DAC control register con-

tents, while Table 16 shows the DAC power-down bit.

Keypad Control Registers

The keypad control register, keypad mask register, and

keypad column mask control register control the key-

pad scanner in the MAX1233/MAX1234. The keypad

control register (Table 17) controls scanning and

debouncing, while the keypad mask register (Table 22)

and the keypad column mask control register (Table 24),

Table 11. Touch-Screen Settling Time

Control*

ST2

0

ST1

0

ST0

0

SETTLING TIME

Settling time: 0µs

0

1

Settling time: 100µs

Settling time: 500µs

Settling time: 1ms

Settling time: 5ms

Settling time: 10ms

Settling time: 50ms

Settling time: 100ms

0

1

0

1

Table 15. DAC Control Register

Descriptions

1

0

1

0

1

BIT

NAME

DAPD

0

DESCRIPTION

DAC powered down

Reserved

1

0

15 (MSB)

[14:0]

1

*Applicable only for X, Y, Z1, and Z2 measurements.

Table 12. ADC Reference Control Bit

Table 16. DAC Power-Down Bit

RFV

FUNCTION

+1.0V reference

+2.5V reference

DAPC

FUNCTION

0

1

0

1

DAC powered up

DAC powered down

Table 13. Internal ADC Reference Auto Power-Up Control

ADC REFERENCE

RES1

RES0

ADC REFERENCE POWER MODE

SOURCE

Power up, wait for reference to settle, and power down again for each

temperature, battery, or auxiliary scan (auto power-up mode)

0

Internal

0

1

0

1

Internal

External

Always powered up

Always powered down

Table 14. DAC Control Register

BIT15 BIT14 BIT13 BIT12 BIT11 BIT10 BIT9

BIT8

BIT7

BIT6

BIT5

BIT4

BIT3

BIT2

BIT1

BIT0

DAPD

0

______________________________________________________________________________________ 23

1ꢀ5k ꢁEDꢂ-rotected TouchꢂEcreen

Controllers Include DAC and Keypad Controller

Table 17. Keypad Control Register

BIT15

BIT14

BIT13 BIT12 BIT11 BIT10 BIT9 BIT8 BIT7 BIT6 BIT5 BIT4 BIT3 BIT2 BIT1 BIT0

HLD HLD

KEYSTS1 KEYSTS0 DBN2 DBN1 DBN0 HLD2

0

Table 18. Keypad Control Register Description

BIT

NAME

KEYSTS1

KEYSTS0

DBN2

DBN1

DBN0

HLD2

DESCRIPTION

15 (MSB)

Read: keypad interrupt status; Write: set interrupt initiated keypad scans

Read: keypad scan status; Write: stop keypad scan

Keypad debounce time control

Keypad hold time control

14

13

12

11

10

9

HLD1

Keypad hold time control

8

HLD0

Keypad hold time control

[7:0]

0

Reserved

Table 19. KEYSTS1/KEYSTS0 Functions

KEYSTS1

KEYSTS0

READ FUNCTION

WRITE FUNCTION

Scans keypad once and waits to detect a button press. Upon

detection, issues an interrupt and waits for the host’s instruction

before scanning.

No button press detected;

scan or debounce in progress

0

Button press detected;

scan or debounce in progress detection, issues an interrupt and scans the keypad.

Stops any ongoing scan and waits to detect a button press. Upon

1

0

1

0

1

Stops any ongoing scan and waits to detect a button press. Upon

detection, issues an interrupt and waits for the host’s instruction

before scanning.

No button press detected;

data available

Button press detected;

data available

Stops any ongoing scan and powers down the button press

detection circuit. No button presses are detected in this mode.

Table 20. Keypad Debounce Time Control

DBN2 DBN1 DBN0

FUNCTION (ms)

Debounce time: 2

0

1

0

1

0

1

0

1

0

1

0

1

0

1

Debounce time: 10

Debounce time: 20

Debounce time: 50

Debounce time: 60

Debounce time: 80

Debounce time: 100

Debounce time: 120

24 ______________________________________________________________________________________

1ꢀ5k ꢁEDꢂ-rotected TouchꢂEcreen

Controllers Include DAC and Keypad Controller

allowing certain keys to be masked from detection.

Tables 18–21 show the programmable bits of the keypad

control register. Tables 23, 24, and 25 show the program-

mable bits of the keypad mask registers. The Keypad

Controller and GPIO section provides more details.

allow the keypad controller’s row and column inputs to be

configured as up to eight parallel I/O pins. Tables 26 and

27 show the GPIO control register layout and control reg-

ister descriptions. Tables 28 and 29 show the GPIO pullup

disable register and associated descriptions. For more

information, see the Applications Information section.

GPIO Control Register

The GPIO control register and the GPIO pullup register

Table 21. Keypad Hold Time Control

HLD2

HLD1

HLD0

FUNCTION

0

1

0

1

0

1

0

1

0

1

0

1

0

1

If a button is held, wait 100µs before beginning next debounce scan

If a button is held, wait 1 debounce time before beginning the next debounce scan

If a button is held, wait 2 debounce times before beginning the next debounce scan

If a button is held, wait 3 debounce times before beginning the next debounce scan

If a button is held, wait 4 debounce times before beginning the next debounce scan

If a button is held, wait 5 debounce times before beginning the next debounce scan

If a button is held, wait 6 debounce times before beginning the next debounce scan

If a button is held, wait 7 debounce times before beginning the next debounce scan

Table 22. Keypad Key Mask Control Register

BIT15 BIT14 BIT13 BIT12 BIT11 BIT10 BIT9

BIT8

BIT7

BIT6

BIT5

BIT4

BIT3

BIT2

BIT1

BIT0

KM15 KM14 KM13 KM12 KM11 KM10 KM9

KM8

KM7

KM6

KM5

KM4

KM3

KM2

KM1

KM0

Table 23. Keypad Key Mask Control Register Descriptions—Individual Mask

BIT

15

14

13

12

11

10

9

NAME

KM15

KM14

KM13

KM12

KM11

KM10

KM9

DESCRIPTION

Mask status register data update on individual key for row 4, column 4

Mask status register data update on individual key for row 3, column 4

Mask status register data update on individual key for row 2, column 4

Mask status register data update on individual key for row 1, column 4

Mask status register data update on individual key for row 4, column 3

Mask status register data update on individual key for row 3, column 3

Mask status register data update on individual key for row 2, column 3

Mask status register data update on individual key for row 1, column 3

Mask status register data update on individual key for row 4, column 2

Mask status register data update on individual key for row 3, column 2

Mask status register data update on individual key for row 2, column 2

Mask status register data update on individual key for row 1, column 2

Mask status register data update on individual key for row 4, column 1

Mask status register data update on individual key for row 3, column 1

Mask status register data update on individual key for row 2, column 1

Mask status register data update on individual key for row 1, column 1

8

KM8

7

KM7

6

KM6

5

KM5

4

KM4

3

KM3

2

KM2

1

KM1

0

KM0

Table 24. Keypad Column Mask Control Register

BIT15 BIT14 BIT13 BIT12 BIT11 BIT10 BIT9

BIT8

BIT7

BIT6

BIT5

BIT4

BIT3

BIT2

BIT1

BIT0

CM4 CM3 CM2 CM1

0

______________________________________________________________________________________ 25

1ꢀ5k ꢁEDꢂ-rotected TouchꢂEcreen

Controllers Include DAC and Keypad Controller

Table 25. Keypad Column Mask Control Register Descriptions

BIT

15

NAME

CM4

CM3

CM2

CM1

0

DESCRIPTION

Mask interrupt, status register, and pending register data update on all keys in column 4

Mask interrupt, status register, and pending register data update on all keys in column 3

Mask interrupt, status register, and pending register data update on all keys in column 2

Mask interrupt, status register, and pending register data update on all keys in column 1

Reserved

14

13

12

[11:0]

Table 26. GPIO Control Register

BIT15 BIT14 BIT13 BIT12 BIT11 BIT10 BIT9

BIT8

BIT7

BIT6

BIT5

BIT4

BIT3

BIT2

BIT1

BIT0

GP7

GP6

GP5

GP4

GP3

GP2

GP1

GP0

OE7

OE6

OE5

OE4

OE3

OE2

OE1

OE0

Table 27. GPIO Control Register Descriptions

DESCRIPTION

BIT

NAME

1

0

15

14

13

12

11

10

9

GP7

GP6

GP5

GP4

GP3

GP2

GP1

GP0

C4 pin becomes GPIO pin 7

C3 pin becomes GPIO pin 6

C2 pin becomes GPIO pin 5

C1 pin becomes GPIO pin 4

R4 pin becomes GPIO pin 3

R3 pin becomes GPIO pin 2

R2 pin becomes GPIO pin 1

R1 pin becomes GPIO pin 0

C4 pin remains keypad column 4

C3 pin remains keypad column 3

C2 pin remains keypad column 2

C1 pin remains keypad column 1

R4 pin remains keypad row 4

R3 pin remains keypad row 3

R2 pin remains keypad row 2

R1 pin remains keypad row 1

GPIO pin configured as an input

8

[7:0]

[OE7:OE0] GPIO pin configured as an output

Table 28. GPIO Pullup Disable Register

BIT15 BIT14 BIT13 BIT12 BIT11 BIT10 BIT9

BIT8

BIT7

BIT6

BIT5

BIT4

BIT3

BIT2

BIT1

BIT0

PU7

PU6

PU5

PU4

PU3

PU2

PU1

PU0

0

Analog Input Data Registers

Table 30 shows the format of the X, Y, Z , Z , BAT1,

BAT2, AUX1, AUX2, TEMP1, and TEMP2 data registers.

The data format for these registers is right justified

beginning with bit 11. Data written through the serial

interface to these registers is not stored.

Table 29. GPIO Pullup Disable Register

Descriptions

1

2

BIT

[15:8] [PU7:PU0]

[7:0]

NAME

DESCRIPTION

1: Pullup disabled. Open collector output.

2: Pullup enabled.

0

Reserved

Keypad Data Registers

Table 31 shows the formatting of the keypad data reg-

isters, while Tables 32, 33, and 34 provide individual

register bit descriptions. These registers have the same

format as the keypad mask register. Each bit repre-

sents one key on the keypad. Table 35 shows a map of

a 16-key keypad. Data written through the serial inter-

face to these registers is not stored.

Data Registers

The data results from conversions or keypad scans are

held in the data registers of the MAX1233/MAX1234.

During power-up, all of these data registers with the

exception of the DAC data register default to 0000 .

H

The DAC register defaults to 1000 .

H

26 ______________________________________________________________________________________

1ꢀ5k ꢁEDꢂ-rotected TouchꢂEcreen

Controllers Include DAC and Keypad Controller

Table 30. Analog Inputs Data Register Format

REGISTER

BIT15 BIT14 BIT13 BIT12 BIT11 BIT10 BIT9 BIT8 BIT7 BIT6 BIT5 BIT4 BIT3 BIT2 BIT1 BIT0

NAME

X

0

X11

Y11

X10

Y10

X9

Y9

X8

Y8

X7

Y7

X6

Y6

X5

Y5

X4

Y4

X3

Y3

X2

Y2

X1

Y1

X0

Y0

Y

Z1

Z1_11 Z1_10 Z1_9 Z1_8 Z1_7 Z1_6 Z1_5 Z1_4 Z1_3 Z1_2 Z1_1 Z1_0

Z2_11 Z2_10 Z2_9 Z2_8 Z2_7 Z2_6 Z2_5 Z2_4 Z2_3 Z2_2 Z2_1 Z2_0

B1_11 B1_10 B1_9 B1_8 B1_7 B1_6 B1_5 B1_4 B1_3 B1_2 B1_1 B1_0

B2_11 B2_10 B2_9 B2_8 B2_7 B2_6 B2_5 B2_4 B2_3 B2_2 B2_1 B2_0

A1_11 A1_10 A1_9 A1_8 A1_7 A1_6 A1_5 A1_4 A1_3 A1_2 A1_1 A1_0

A2_11 A2_10 A2_9 A2_8 A2_7 A2_6 A2_5 A2_4 A2_3 A2_2 A2_1 A2_0

T1_11 T1_10 T1_9 T1_8 T1_7 T1_6 T1_5 T1_4 T1_3 T1_2 T1_1 T1_0

T2_11 T2_10 T2_9 T2_8 T2_7 T2_6 T2_5 T2_4 T2_3 T2_2 T2_1 T2_0

Z2

BATT1

BATT2

AUX1

AUX2

TEMP1

TEMP2

Table 31. Keypad Data Registers

REGISTER

NAME

BIT15 BIT14 BIT13 BIT12 BIT11 BIT10 BIT9 BIT8 BIT7 BIT6 BIT5 BIT4 BIT3 BIT2 BIT1 BIT0

KBD

K15 K14 K13 K12 K11 K10 K9 K8 K7 K6 K5 K4 K3 K2 K1 K0

KPData1 K1_15 K1_14 K1_13 K1_12 K1_11 K1_10 K1_9 K1_8 K1_7 K1_6 K1_5 K1_4 K1_3 K1_2 K1_1 K1_0

KPData2 K2_15 K2_14 K2_13 K2_12 K2_11 K2_10 K2_9 K2_8 K2_7 K2_6 K2_5 K2_4 K2_3 K2_2 K2_1 K2_0

Table 32. Keypad Data Register Descriptions

BIT

15

14

13

12

11

10

9

NAME

K15

K14

K13

K12

K11

K10

K9

DESCRIPTION

Keypad scan result for row 4, column 4. Can only be masked by column mask.

Keypad scan result for row 3, column 4. Can only be masked by column mask.

Keypad scan result for row 2, column 4. Can only be masked by column mask.

Keypad scan result for row 1, column 4. Can only be masked by column mask.

Keypad scan result for row 4, column 3. Can only be masked by column mask.

Keypad scan result for row 3, column 3. Can only be masked by column mask.

Keypad scan result for row 2, column 3. Can only be masked by column mask.

Keypad scan result for row 1, column 3. Can only be masked by column mask.

Keypad scan result for row 4, column 2. Can only be masked by column mask.

Keypad scan result for row 3, column 2. Can only be masked by column mask.

Keypad scan result for row 2, column 2. Can only be masked by column mask.

Keypad scan result for row 1, column 2. Can only be masked by column mask.

Keypad scan result for row 4, column 1. Can only be masked by column mask.

Keypad scan result for row 3, column 1. Can only be masked by column mask.

Keypad scan result for row 2, column 1. Can only be masked by column mask.

Keypad scan result for row 1, column 1. Can only be masked by column mask.

8

K8

7

K7

6

K6

5

K5

4

K4

3

K3

2

K2

1

K1

0

K0

______________________________________________________________________________________ 27

1ꢀ5k ꢁEDꢂ-rotected TouchꢂEcreen

Controllers Include DAC and Keypad Controller

Table 33. Keypad Data Register 1 (Pending Register) Descriptions

BIT

15

14

13

12

11

10

9

NAME

K1_15

K1_14

K1_13

K1_12

K1_11

K1_10

K1_9