MAXIM MAX1233, MAX1234 User Manual
General Description
The MAX1233/MAX1234 are complete PDA controllers in
5mm × 5mm, 28-pin QFN and TQFN packages. They feature a 12-bit analog-to-digital converter (ADC), low onresistance switches for driving resistive touch screens, an
internal +1.0V/+2.5V or external reference, ±2°C accurate, on-chip temperature sensor, direct +6V battery monitor, 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.
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. Softwareconfigurable 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.
Applications
Personal Digital Assistants
Pagers
Touch-Screen Monitors
Cellular Phones
MP3 Players
Portable Instruments
Point-of-Sale Terminals
Features
♦ 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 AVDD)
♦ SPI™/QSPI™/MICROWIRE™-Compatible 10MHz
Serial Interface
♦ 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,
and End of Conversion
♦ Programmable 8-, 10-, 12-Bit Resolution
♦ Programmable Conversion Rates
♦ AutoShutdown
™
Between Conversions
♦ Low Power
260µA at 50ksps
50µA at 10ksps
6µA at 1ksps
0.3µA Shutdown Current
♦ 28-Pin 5mm × 5mm QFN and TQFN Packages
MAX1233/MAX1234
±15kV ESD-Protected Touch-Screen
Controllers Include DAC and Keypad Controller
________________________________________________________________
Maxim Integrated Products
1
Pin Configuration
Ordering Information
19-2512; Rev 4; 3/08
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
EVALUATION KIT
AVAILABLE
TransZorb is a trademark of General Semiconductor Industries, Inc.
SPI and QSPI are trademarks of Motorola, Inc.
MICROWIRE is a trademark of National Semiconductor Corp.
AutoShutdown is a trademark of Maxim Integrated Products, Inc.
TOP VIEW
1
DV
DD
2
AV
DD
3
*X+
4
*Y+
5
*X-
6
*Y-
7
GND
*PIN INCLUDES 8kV/15kV ESD PROTECTION.
DIN
DOUT
PENIRQ
BUSY
SCLK
CS
28272625242322
MAX1233
MAX1234
8
9
1011121314
*BAT2
*AUX1
*AUX2
QFN/TQFN
REF
DACOUT
*BAT1
KEYIRQ
R4
21
C4
20
C3
19
C2
18
C1
17
R1
16
R2
15
R3
PART TEMP RANGE PIN-PACKAGE
MAX1233EGI -40°C to +85°C 28 QFN (5mm x 5mm)
MAX1233ETI -40°C to +85°C 28 TQFN (5mm x 5mm)
MAX1234EGI -40°C to +85°C 28 QFN (5mm x 5mm)
MAX1234ETI -40°C to +85°C 28 TQFN (5mm x 5mm)
MAX1233/MAX1234
±15kV ESD-Protected Touch-Screen
Controllers Include DAC and Keypad Controller
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(DVDD= AVDD= +2.7V to +3.6V (MAX1233), DVDD= AVDD= +4.75V to +5.25V (MAX1234), external reference V
REF
= 2.5V
(MAX1233), V
REF
= 4.096V (MAX1234); f
SCLK
= 10MHz, f
SAMPLE
= 50ksps, 12-bit mode, 0.1µF capacitor at REF, TA= -40°C to
+85°C, unless otherwise noted. Typical values are at T
A
= +25°C.)
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.
AVDDto GND............................................................-0.3V to +6V
DV
DD
to AVDD.......................................................-0.3V to +0.3V
Digital Inputs/Outputs to GND .................-0.3V to (DV
DD
+ 0.3V)
X+, Y+, X-, Y-, AUX1, AUX2,
and REF to GND ..................................-0.3V to (AV
DD
+ 0.3V)
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
All Other Pins.....................................................................±2.5kV
Maximum Current into Any Pin............................................50mA
Continuous Power Dissipation (T
A
= +70°C)
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
DC ACCURACY (Note 1)
Resolution Software-programmable 8/10/12 bit 12 Bits
No Missing Codes 11 Bits
Relative Accuracy (Note 2) INL
Differential Nonlinearity DNL
Offset Error
Total Unadjusted Error TUE
Offset Temperature Coefficient ±0.4 ppm/°C
Gain Temperature Coefficient ±0.4 ppm/°C
Channel-to-Channel Offset ±0.1 LSB
Channel-to-Channel Gain
Matching
Noise Including internal V
Power-Supply Rejection PSR
DYNAMIC SPECIFICATIONS (1kHz SINE WAVE, VIN = 2.5V
= 10MHz)
f
SCLK
Signal-to-Noise Plus Distortion SINAD 69 dB
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
ANALOG-TO-DIGITAL CONVERTER
12-bit mode ±0.8 ±2
10-bit and 8-bit modes ±0.5
12-bit mode ±0.8 ±2
10-bit and 8-bit modes ±0.5
12-bit mode ±0.5 ±4
10-bit and 8-bit modes ±0.5
12-bit mode ±0.5 ±4
10-bit mode ±0.5Gain Error (Note 3)
8-bit mode ±0.5
12-bit mode ±2
10-bit and 8-bit modes ±1
Full-scale
input
REF
MAX1233
AV
= DVDD = +2.7V to +3.6V
DD
MAX1234
AV
= DVDD = +5V ±5%
DD
FOR MAX1233, VIN = 4.096V
P-P
±0.1 LSB
50 µV
±0.4
±0.3
FOR MAX1234, 50ksps,
P-P
LSB
LSB
LSB
LSB
LSB
RMS
mV
MAX1233/MAX1234
±15kV ESD-Protected Touch-Screen
Controllers Include DAC and Keypad Controller
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(DVDD= AVDD= +2.7V to +3.6V (MAX1233), DVDD= AVDD= +4.75V to +5.25V (MAX1234), external reference V
REF
= 2.5V
(MAX1233), V
REF
= 4.096V (MAX1234); f
SCLK
= 10MHz, f
SAMPLE
= 50ksps, 12-bit mode, 0.1µF capacitor at REF, TA= -40°C to
+85°C, unless otherwise noted. Typical values are at T
A
= +25°C.)
Total Harmonic Distortion THD -84 dB
Spurious-Free Dynamic Range SFDR 84 dB
Full-Power Bandwidth -3dB point 0.5 MHz
Full-Linear Bandwidth SINAD > 67dB 50 kHz
CONVERSION RATE
Internal Oscillator Frequency 8 11.5 MHz
Aperture Delay 30 ns
Aperture Jitter <50 ps
Maximum Serial Clock Frequency f
Duty Cycle 30 70 %
AUXILIARY ANALOG INPUTS (AUX1, AUX2)
Input Voltage Range 0V
Input Leakage Current
Input Capacitance 34 pF
BATTERY MONITOR INPUTS (BAT1, BAT2)
Input Voltage Range 0.5 6.0 V
Input Impedance
Accuracy Internal reference -3 +3 %
TEMPERATURE MEASUREMENT
Temperature Range -40 +85 °C
Resolution
Accuracy
INTERNAL ADC REFERENCE
Reference Output Voltage V
Output Tempco TCV
Reference Output Impedance Normal operation 250 Ω
Reference Short-Circuit Current 18 mA
EXTERNAL ADC REFERENCE (INTERNAL REFERENCE DISABLED, REFERENCE APPLIED TO REF)
Reference Input Voltage Range (Note 6) 1.0 V
Input Impedance CS = GND or V
Input Current
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
SCLK
REF
REF
Channel not selected or conversion
stopped
Sampling battery 10 kΩ
Battery monitor OFF 1 GΩ
Differential method (Note 4) 1.6
Single measurement method (Note 5) 0.3
Differential method (Note 4) ±3
Single measurement method (Note 5) ±2
2.5V mode, TA = +25°C 2.470 2.500 2.530
1.0V mode, TA = +25°C 0.980 1.000 1.020
V
V
Shutdown/between conversions ±0.1
= +2.5V at 50ksps (MAX1233) 5 10
REF
= +4.096V at 50ksps (MAX1234) 8 15
REF
10 MHz
REF
±0.1 ±1µA
60 ppm/°C
DD
1GΩ
DD
°C
°C
µA
V
V
V
MAX1233/MAX1234
±15kV ESD-Protected Touch-Screen
Controllers Include DAC and Keypad Controller
4 _______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS (continued)
(DVDD= AVDD= +2.7V to +3.6V (MAX1233), DVDD= AVDD= +4.75V to +5.25V (MAX1234), external reference V
REF
= 2.5V
(MAX1233), V
REF
= 4.096V (MAX1234); f
SCLK
= 10MHz, f
SAMPLE
= 50ksps, 12-bit mode, 0.1µF capacitor at REF, TA= -40°C to
+85°C, unless otherwise noted. Typical values are at T
A
= +25°C.)
DC ACCURACY
Resolution 8Bits
Integral Linearity Error INL (Note 7) ±1.0 LSB
Differential Linearity Error DNL No missing codes ±1.0 LSB
Offset Error V
Offset Error Temperature
Coefficient
Full-Scale Error Code = 255, no load 5 %
Full-Scale Error Temperature
Coefficient
DYNAMIC PERFORMANCE
Voltage Output Slew Rate Positive and negative 0.4 V/µs
Output Settling Time 0.5LSB; 50kΩ and 50pF load (Note 9) 20 µs
Glitch Impulse Code 127 to 128 40 nV/s
Wake-Up Time From shutdown 50 µs
DAC OUTPUT
Internal DAC Reference V
Output Load Regulation
Output Resistance Power-down mode 1.0 MΩ
On-Resistance
Touch-Detection Internal Pullup
Resistance
Pullup Resistance C4, C3, C2, C1 (Note 11) 0.5 kΩ
Pulldown Resistance R4, R3, R2, R1 (Note 11) 16 kΩ
DIGITAL INPUTS (SCLK, CS, DIN, R_, C_)
Input Voltage Low V
Input Voltage High V
Input Leakage Current I
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
REFDAC
DIGITAL-TO-ANALOG CONVERTER
OS
(Note 8) ±1 ±25 mV
Code = 255, no load ±10 ppm/°C
(Note 10)
Code = 255; 0 to 100µA 0.5
Code = 0; 0 to 100µA 0.5
TOUCH-SCREEN CONTROLLER
Y+, X+ 7
Y-, X- 9
X+ to AV
IL
IH
L
DD
KEYPAD CONTROLLER
DIGITAL INTERFACE
0.85
AV
0.7
DV
1 ppm/°C
✕
DD
✕
DD
✕
0.9
AV
DD
1MΩ
±0.1 ±1µA
0.95
AV
0.3
DV
✕
DD
✕
DD
V
LSB
Ω
V
V
MAX1233/MAX1234
±15kV ESD-Protected Touch-Screen
Controllers Include DAC and Keypad Controller
_______________________________________________________________________________________ 5
ELECTRICAL CHARACTERISTICS (continued)
(DVDD= AVDD= +2.7V to +3.6V (MAX1233), DVDD= AVDD= +4.75V to +5.25V (MAX1234), external reference V
REF
= 2.5V
(MAX1233), V
REF
= 4.096V (MAX1234); f
SCLK
= 10MHz, f
SAMPLE
= 50ksps, 12-bit mode, 0.1µF capacitor at REF, TA= -40°C to
+85°C, unless otherwise noted. Typical values are at T
A
= +25°C.)
Note 1: Tested at DVDD= AVDD= +2.7V (MAX1233), DVDD= AVDD= +5V (MAX1234).
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
TEMP2
- V
TEMP1
) × 2680°K/V. No calibration is necessary.
Note 5: Temperature coefficient is -2.1mV/°C. Determine absolute temperature by extrapolating from a calibrated value.
Note 6: ADC performance is limited by the conversion noise floor, typically 300µV
P-P
. An external reference below 2.5V can
compromise the ADC performance.
Note 7: Guaranteed from code 5 to 255.
Input Capacitance C
DIGITAL OUTPUT (DOUT)
Output Voltage Low V
Output Voltage High V
DIGITAL OUTPUT (BUSY, PENIRQ, KEYIRQ, R_, C_)
Output Voltage Low V
Output Voltage High V
Supply Voltage (Note 12)
Analog and Digital Supply
Current
TIMING CHARACTERISTICS
SCLK Clock Period t
SCLK Pulse Width High t
SCLK Pulse Width Low t
DIN to SCLK Rise Setup t
SCLK Rise to DIN Hold t
SCLK Fall to DOUT Valid t
CS Fall to DOUT Enabled t
CS Rise to DOUT Disabled t
CS Fall to SCLK Rise t
CS Fall to SCLK Ignored t
SCLK Rise to R_/C_ Data Valid t
CS Pulse Width High t
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
IN
OL
OH
OL
OH
15 pF
I
= 2mA 0.4
SINK
I
= 4mA 0.8
SINK
DV
-
DV
DD
0.5
DD
0.5
-
I
I
I
= 1.5mA
SOURCE
= 0.2mA 0.4 V
SINK
= 0.2mA
SOURCE
POWER REQUIREMENTS
AV
DV
DD
MAX1233 2.7 3 3.6
/
DD MAX1234 4.75 5 5.25
Idle; all blocks shut down 0.5 5
I
AVDD
I
DVDD
Only ADC on; f
+
Only DAC on; no load 150 230
= 20ksps 150 500
SAMPLE
Only internal reference on 670 900
CP
CH
CL
DS
DH
DOV
DV
DOD
CSS
CSH
GPO
CSW
C
= 50pF 40 ns
LOAD
C
= 50pF 45 ns
LOAD
C
= 50pF 40 ns
LOAD
C
= 50pF (Note 13) 230 ns
LOAD
100 ns
40 ns
40 ns
40 ns
0ns
40 ns
0ns
40 ns
V
V
V
V
µA
MAX1233/MAX1234
±15kV ESD-Protected Touch-Screen
Controllers Include DAC and Keypad Controller
6 _______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS (continued)
(DVDD= AVDD= +2.7V to +3.6V (MAX1233), DVDD= AVDD= +4.75V to +5.25V (MAX1234), external reference V
REF
= 2.5V
(MAX1233), V
REF
= 4.096V (MAX1234); f
SCLK
= 10MHz, f
SAMPLE
= 50ksps, 12-bit mode, 0.1µF capacitor at REF, TA= -40°C to
+85°C, unless otherwise noted. Typical values are at T
A
= +25°C.)
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
DD
and DVDDshould not differ by more than 300mV.
Note 13: When configured as GPIO.
SCLK
DIN
DOUT
NOTE: TIMING NOT TO SCALE.
R_/C_
CS
t
CL
t
DH
t
DV
t
DS
t
CH
t
CSS
t
CP
t
CSH
t
CSW
t
CSH
t
CSS
t
DOD
t
DOV
t
GPO
Timing Diagram
MAX1233/MAX1234
±15kV ESD-Protected Touch-Screen
Controllers Include DAC and Keypad Controller
_______________________________________________________________________________________ 7
Typical Operating Characteristics
(AV
DD
= DVDD= 3V (MAX1233) or 5V (MAX1234), external V
REF
= +2.5V (MAX1233), external V
REF
= +4.096V (MAX1234), f
SCLK
=
10MHz (50% duty cycle), f
SAMPLE
= 20ksps, C
LOAD
= 50pF, 0.1µF capacitor at REF, TA= +25°C, unless otherwise noted.)
SHUTDOWN CURRENT
vs. ANALOG SUPPLY VOLTAGE
300
250
200
150
100
SHUTDOWN CURRENT (nA)
50
0
2.7
AVDD (V)
MAX1233/34 toc01
5.24.74.23.73.2
INTERNAL OSCILLATOR FREQUENCY
vs. TEMPERATURE
9.8
9.6
MAX1234, AVDD = +5.0V
9.4
9.2
9.0
MAX1233, AVDD = +3.0V
8.8
INTERNAL OSCILLATOR FREQUENCY (MHz)
8.6
-40
TEMPERATURE (°C)
MAX1233/34 toc04
806040200-20
TEMP2 DIODE VOLTAGE
vs. ANALOG SUPPLY VOLTAGE
0.80
SHUTDOWN CURRENT
vs. TEMPERATURE
300
250
200
150
100
SHUTDOWN CURRENT (nA)
50
0
-40
TEMPERATURE (°C)
806040200-20
10.0
MAX1233/34 toc02
INTERNAL OSCILLATOR FREQUENCY (MHz)
TEMP1 DIODE VOLTAGE
vs. ANALOG SUPPLY VOLTAGE
0.70
0.68
0.66
0.64
0.62
0.60
0.58
0.56
TEMP1 DIODE VOLTAGE (V)
0.54
0.52
0.50
2.7
5.24.74.23.73.2
AVDD (V)
0.80
0.75
MAX1233/34 toc05
0.70
0.65
0.60
0.55
TEMP1 DIODE VOLTAGE (V)
0.50
0.45
0.40
TEMP2 DIODE VOLTAGE
vs. TEMPERATURE
0.90
INTERNAL OSCILLATOR FREQUENCY
vs. ANALOG SUPPLY VOLTAGE
9.8
9.6
9.4
9.2
9.0
8.8
8.6
8.4
8.2
8.0
2.7
TEMP1 DIODE VOLTAGE
vs. TEMPERATURE
-40
TEMPERATURE (°C)
MAX1233/MAX1234
AVDD (V)
8065-25 -10 5 3520 50
MAX1233/34 toc03
5.24.74.23.73.2
MAX1233/34 toc06
0.75
0.70
TEMP2 DIODE VOLTAGE (V)
0.65
0.60
2.7
AVDD (V)
5.24.74.23.73.2
MAX1233/34 toc07
0.85
0.80
0.75
0.70
TEMP2 DIODE VOLTAGE (V)
0.65
0.60
-40
TEMPERATURE (°C)
MAX1233/34 toc08
80655035205-10-25
MAX1233/MAX1234
±15kV ESD-Protected Touch-Screen
Controllers Include DAC and Keypad Controller
8 _______________________________________________________________________________________
Typical Operating Characteristics (continued)
(AV
DD
= DVDD= 3V (MAX1233) or 5V (MAX1234), external V
REF
= +2.5V (MAX1233), external V
REF
= +4.096V (MAX1234), f
SCLK
=
10MHz (50% duty cycle), f
SAMPLE
= 20ksps, C
LOAD
= 50pF, 0.1µF capacitor at REF, TA= +25°C, unless otherwise noted.)
ADC DIFFERENTIAL NONLINEARITY
vs. OUTPUT CODE
MAX1233/34 toc10
OUTPUT CODE
DNL (LSB)
400035002500 30001000 1500 2000500
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1.0
-1.0
0
ADC OFFSET ERROR
vs. ANALOG SUPPLY VOLTAGE
MAX1233/34 toc11
AVDD (V)
OFFSET ERROR (LSB)
5.24.73.2 3.7 4.2
-1.5
-1.0
-0.5
0
0.5
1.0
1.5
2.0
-2.0
2.7
ADC OFFSET ERROR vs. TEMPERATURE
MAX1233/34 toc12
TEMPERATURE (°C)
OFFSET ERROR (LSB)
8060-20 0 20 40
-1.5
-1.0
-0.5
0
0.5
1.0
1.5
2.0
-2.0
-40
ADC GAIN ERROR
vs. ANALOG SUPPLY VOLTAGE
MAX1233/34 toc13
AVDD (V)
GAIN ERROR (LSB)
5.24.73.2 3.7 4.2
-1.5
-1.0
-0.5
0
0.5
1.0
1.5
2.0
-2.0
2.7
ADC GAIN ERROR
vs. TEMPERATURE
MAX1233/34 toc14
TEMPERATURE (°C)
GAIN ERROR (LSB)
-1.5
-1.0
-0.5
0
0.5
1.0
1.5
2.0
-2.0
8060-20 0 20 40-40
ADC INTEGRAL NONLINEARITY
vs. OUTPUT CODE
MAX1233/34 toc09
OUTPUT CODE
INL (LSB)
400035002500 30001000 1500 2000500
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1.0
-1.0
0
MAX1233/MAX1234
-0.050
-0.075
-0.100
-0.025
0
0.025
0.050
0.075
0 100 200 300
DAC INTEGRAL NONLINEARITY vs. CODE
MAX1233/34 toc19
CODE
INL (LSB)
50
150
250
DAC DIFFERENTIAL NONLINEARITY
vs. OUTPUT CODE
MAX1233/34 toc20
OUTPUT CODE
DNL (LSB)
25020015010050
-0.075
-0.500
-0.025
0
0.025
0.050
0.075
-0.100
0 300
Typical Operating Characteristics (continued)
(AV
DD
= DVDD= 3V (MAX1233) or 5V (MAX1234), external V
REF
= +2.5V (MAX1233), external V
REF
= +4.096V (MAX1234), f
SCLK
=
10MHz (50% duty cycle), f
SAMPLE
= 20ksps, C
LOAD
= 50pF, 0.1µF capacitor at REF, TA= +25°C, unless otherwise noted.)
±15kV ESD-Protected Touch-Screen
Controllers Include DAC and Keypad Controller
_______________________________________________________________________________________ 9
ADC EXTERNAL REFERENCE INPUT
CURRENT vs. SAMPLING RATE
8
MAX1233
= +2.5V
V
REF
6
1000
MAX1233/34 toc15
100
ADC SUPPLY CURRENT
vs. SAMPLING RATE
MAX1233/34 toc16
4
REFERENCE CURRENT (μA)
2
0
100 100k
f
SAMPLE
10k1k
(Hz)
ADC SUPPLY CURRENT
vs. SUPPLY VOLTAGE
250
200
150
100
SUPPLY CURRENT (μA)
50
0
AVDD (V)
EXTERNAL REF
= 20ksps
f
SAMPLE
5.24.74.23.73.22.7
MAX1233/34 toc17
10
SUPPLY CURRENT (μA)
1
0.1
1 100k10 1k
ADC SUPPLY CURRENT
140
120
100
80
60
SUPPLY CURRENT (μA)
40
20
0
f
(Hz)
SAMPLE
vs. TEMPERATURE
TEMPERATURE (°C)
10k100
AVDD = +3V
MAX1233/34 toc18
8060-20 0 20 40-40
MAX1233/MAX1234
±15kV ESD-Protected Touch-Screen
Controllers Include DAC and Keypad Controller
10 ______________________________________________________________________________________
Typical Operating Characteristics (continued)
(AV
DD
= DVDD= 3V (MAX1233) or 5V (MAX1234), external V
REF
= +2.5V (MAX1233), external V
REF
= +4.096V (MAX1234), f
SCLK
=
10MHz (50% duty cycle), f
SAMPLE
= 20ksps, C
LOAD
= 50pF, 0.1µF capacitor at REF, TA= +25°C, unless otherwise noted.)
DAC FULL-SCALE ERROR
vs. ANALOG SUPPLY VOLTAGE
0.75
MAX1233/34 toc21
1.2
DAC FULL-SCALE ERROR
0.75
vs. TEMPERATURE
MAX1233/34 toc22
1.2
0.50
0.25
0
-0.25
FULL-SCALE ERROR (LSB)
-0.50
-0.75
2.5 4.03.0 3.5 4.5 5.0 5.5
AVDD (V)
DAC SUPPLY CURRENT
vs. ANALOG SUPPLY VOLTAGE
250
200
150
100
DAC SUPPLY CURRENT (μA)
50
0
AVDD (V)
5.24.74.23.73.22.7
0.8
0.4
0
-0.4
FULL-SCALE ERROR (%)
-0.8
-1.2
MAX1233/34 toc23
0.50
0.25
0
-0.25
FULL-SCALE ERROR (LSB)
-0.50
-0.75
-40 20-20 0 40 60 80
TEMPERATURE (°C)
DAC SUPPLY CURRENT
vs. TEMPERATURE
200
175
150
125
100
75
50
DAC SUPPLY CURRENT (μA)
25
0
-40
TEMPERATURE (°C)
0.8
0.4
0
-0.4
FULL-SCALE ERROR (%)
-0.8
-1.2
MAX1233/34 toc24
8060-20 0 20 40
ADC REFERENCE VOLTAGE
vs. TEMPERATURE
TEMPERATURE (°C)
MAX1233/34 toc26
V
= 1.0V
REF
V
= 2.5V
REF
(V)
V
REF
2.550
2.525
2.500
2.475
2.450
ADC REFERENCE VOLTAGE
vs. ANALOG SUPPLY VOLTAGE
V
AVDD (V)
MAX1233/34 toc25
= 1.0V
REF
V
= 2.5V
REF
(V)
REF
V
2.60
2.55
2.50
2.45
2.40
1.020
1.010
(V)
1.000
REF
V
0.990
0.980
5.24.74.23.73.22.7
1.250
1.125
(V)
1.000
REF
V
0.875
0.750
8060-20 0 20 40-40
MAX1233/MAX1234
±15kV ESD-Protected Touch-Screen
Controllers Include DAC and Keypad Controller
______________________________________________________________________________________ 11
Typical Operating Characteristics (continued)
(AV
DD
= DVDD= 3V (MAX1233) or 5V (MAX1234), external V
REF
= +2.5V (MAX1233), external V
REF
= +4.096V (MAX1234), f
SCLK
=
10MHz (50% duty cycle), f
SAMPLE
= 20ksps, C
LOAD
= 50pF, 0.1µF capacitor at REF, TA= +25°C, unless otherwise noted.)
ADC REFERENCE SUPPLY CURRENT
vs. ANALOG SUPPLY VOLTAGE
MAX1233/34 toc27
AVDD (V)
SUPPLY CURRENT (μA)
4.74.23.73.2
600
650
700
750
550
2.7 5.2
REFERENCE SUPPLY CURRENT
vs. TEMPERATURE
MAX1233/34 toc28
TEMPERATURE (°C)
SUPPLY CURRENT (μA)
600
650
700
750
550
8065-25 -10 5 3520 50-40
PIN NAME FUNCTION
1DV
DD
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
DD
.
2AV
DD
Positive Analog 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 DV
DD
.
3* X+ X+ Position Input
4* Y+ Y+ Position Input
5* X- X- Position Input
6* Y- Y- Position Input
7 GND Analog and Digital Ground
8* BAT1 Battery Monitoring Input 1. Measures battery voltages up to 6V.
9* BAT2 Battery Monitoring Input 2. Measures battery voltages up to 6V.
10* AUX1 Auxiliary Analog Input 1 to ADC. Measures analog voltages from zero to V
REF
.
11* AUX2 Auxiliary Analog Input 2 to ADC. Measures analog voltages from zero to V
REF
.
12 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
DD
. Bypass REF to GND with a 0.1µF
capacitor in the external reference mode only.
13
DAC Voltage Output; 0.9 × AVDD Full Scale
14 R4 Keypad Row 4. Can be reconfigured as GPIO3.
15 R3 Keypad Row 3. Can be reconfigured as GPIO2.
16 R2 Keypad Row 2. Can be reconfigured as GPIO1.
17 R1 Keypad Row 1. Can be reconfigured as GPIO0.
18 C1 Keypad Column 1. Can be reconfigured as GPIO4.
Pin Description
DACOUT
MAX1233/MAX1234
±15kV ESD-Protected Touch-Screen
Controllers Include DAC and Keypad Controller
12 ______________________________________________________________________________________
Detailed Description
The MAX1233/MAX1234 are 4-wire touch-screen controllers. Figure 1 shows the functional diagram of the
MAX1233/MAX1234. Each device includes a 12-bit sampling 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 onresistance switches for driving touch screens.
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.
Touch-Screen Operation
The 4-wire touch-screen controller works by creating a
voltage gradient across the vertical or horizontal resistive 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 internal MOSFET switches that connect each resistive layer
to AVDDand ground. For example, to measure the Y
position when a pointing device presses on the touch
screen, the Y+ and Y- drivers are turned on, connecting
one side of the vertical resistive layer to AVDDand the
other side to ground. The horizontal resistive layer functions as a sense line. One side of this resistive layer gets
connected to the X+ input, while the other side is left
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 converter senses the voltage at the point of contact through the
X+ input and digitizes it.
12-Bit ADC
Analog Inputs
Figure 3 shows a block diagram of the ADC’s analog
input section including the input multiplexer, the differential input, and the differential reference. The input multiplexer switches between X+, X-, Y+, Y-, AUX1, AUX2,
BAT1, BAT2, and the internal temperature sensor.
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
ACQ
) is the maximum
time the device takes to acquire the input signal to 12bit accuracy. Configure t
ACQ
by writing to the ADC
control register. See Table 1 for the maximum input signal source impedance (R
SOURCE
) for complete settling
during acquisition.
Accommodate higher source impedances by placing a
0.1µF capacitor between the analog input and GND.
Input Bandwidth
The ADC’s input-tracking circuitry has a 0.5MHz smallsignal bandwidth. To avoid high-frequency signals
being aliased into the frequency band of interest, antialias filtering is recommended.
Pin Description (continued)
*
ESD protected: ±8kV Contact, ±15kV Air.
PIN NAME FUNCTION
19 C2 Keypad Column 2. Can be reconfigured as GPIO5.
20 C3 Keypad Column 3. Can be reconfigured as GPIO6.
21 C4 Keypad Column 4. Can be reconfigured as GPIO7.
22 KEYIRQ Active-Low Keypad Interrupt. KEYIRQ is low when a key press is detected.
23 PENIRQ Active-Low Pen Touch Interrupt. PENIRQ is low when a screen touch is detected.
24 DOUT Serial Data Output. Data is clocked out at SCLK falling edge. High impedance when CS is high.
25 BUSY
26 DIN Serial Data Input. Data is clocked in on the rising edge of SCLK.
27 SCLK
28 CS
—EP
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.
Serial Clock Input. Clocks data in and out of the serial interface and sets the conversion speed (duty
cycle must be 30% to 70%).
Active-Low Chip Select. Data is not clocked into DIN unless CS is low. When CS is high, DOUT is
high impedance.
Exposed Pad. Internally connected to GND. Connect to a large ground plane to maximize thermal
performance. Not intended as an electrical connection point.
MAX1233/MAX1234
±15kV ESD-Protected Touch-Screen
Controllers Include DAC and Keypad Controller
______________________________________________________________________________________ 13
Figure 1. Block Diagram
Figure 2. Touch-Screen Measurement
Table 1. Maximum Input Source
Impedance
*X+
*Y+
*BAT1
*BAT2
*AUX1
*AUX2
REF
DACOUT
C1 C2 C3 C4 R1 R2 R3 R4
INTERNAL
REFERENCE
2.5V/1.0V
KEYPAD CONTROLLER
AND GPIO
REGISTERS AND
SCAN STATE
CONTROL
SERIAL
DATA
I/O
DOUT
SCLK
DIN
CS
PENIRQ
KEYIRQ
BUSY
OSCILLATOR
MAX1233
MAX1234
TEMP
SENSOR
*X-
*Y-
X/Y SWITCHES
BATTERY MONITOR
BATTERY MONITOR
8-BIT
DAC
REF
DAC
MUX
12-BIT
ADC
*ESD PROTECTED
+AV
FORCE LINE
Y+
SENSE LINE
X+
FORCE LINE
Y-
GND
DD
SENSE
LINE
ACQUISITION
TIME (µs)
1.5 8 2.6
1.5 10 2.0
+REF
+IN
-IN
-REF
1.5 12 1.5
5.0 8 23
5.0 10 19
5.0 12 15
95 8 560
95 10 470
95 12 400
RESOLUTION
(BITS)
MAXIMUM R
SOURCE
FOR
COMPLETE SETTLING
DURING ACQUISITION (kΩ)
MAX1233/MAX1234
±15kV ESD-Protected Touch-Screen
Controllers Include DAC and Keypad Controller
14 ______________________________________________________________________________________
Analog Input Protection
Internal protection diodes that clamp the analog input
to AVDDand GND allow the analog input pins to swing
from GND - 0.3V to AVDD+ 0.3V without damage.
Analog inputs must not exceed AV
DD
by more than
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
to ±8kV, using the Contact-Discharge method and
±15kV using the Air-Gap method specified in IEC1000-4-2.
Reference for ADC
Internal Reference
The MAX1233/MAX1234 offer an internal voltage reference 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
Figure 3. Simplified Diagram of Analog Input Section
TEMP1
TEMP2
X+
X-
Y+
Y-
+AV
DD
V
REF
MAX1233
MAX1234
REF ON/OFF
CONVERTER
+REF
-
REF
2.5V/1.0V
REFERENCE
+IN
-IN
7.5kΩ
V
BAT1
7.5kΩ
V
BAT2
AUX1
AUX2
GND
2.5kΩ
BATTERY
ON
2.5kΩ
BATTERY
ON
Loading...