±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller

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±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller

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19-2512; 7/02
±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller
MAX1233/MAX1234 complete controllers 5mm, 28-pin package. They feature 12-bit analog-to-digital converter (ADC), on-resistance switches driving resistive touch screens, internal +1.0V/+2.5V external reference, ±2°C accurate, on-chip temperature sensor, direct battery monitor, keypad controller, 8-bit digital-to-analog converter (DAC), synchronous serial interface. Each keypad controllers' eight column inputs reconfigured general-purpose parallel pins (GPIO). analog inputs fully protected, eliminating need external TransZorbdevices. MAX1233/MAX1234 offer programmable resolution sampling rates. Interrupts from devices alert host processor when data ready, when screen touched, press detected. Softwareconfigurable scan control internal timers give user flexibility without burdening host processor. These devices consume only 260µA maximum sampling rate 50ksps. Supply current falls below 50µA sampling rates 10ksps. MAX1233/MAX1234 guaranteed over -40°C +85°C temperature range.
ATION EVALU AILABL
Features
ESD-Protected Analog Inputs ±15kV 1000-4-2 Air-Gap Discharge ±8kV 1000-4-2 Contact Discharge Single-Supply Operation +2.7V +3.6V (MAX1233) +4.75V +5.25V (MAX1234) 4-Wire Touch-Screen Interface Internal +1.0V/+2.5V Reference External Reference (+1.0V AVDD) 10MHz Serial Interface 12-Bit, 50ksps Measures Resistive Touch-Screen Position Pressure Auxiliary Analog Inputs Battery Voltages (0.5V On-Chip Temperature 8-Bit Bias Control Keypad Programmable Controller Offers Eight GPIO Pins Automatic Detection Screen Touch, Press, Conversion Programmable 10-, 12-Bit Resolution Programmable Conversion Rates AutoShutdownBetween Conversions Power 260µA 50ksps 50µA 10ksps 1ksps 0.3µA Shutdown Current 28-Pin Package
MAX1233/MAX1234
Applications
Personal Digital Assistants Pagers Touch-Screen Monitors Cellular Phones Players Portable Instruments Point-of-Sale Terminals
Configuration
PENIRQ
DOUT
BUSY
SCLK
VIEW
KEYIRQ
DVDD AVDD *X*YGND
Ordering Information
PART MAX1233EGI MAX1234EGI TEMP RANGE -40°C +85°C -40°C +85°C PIN-PACKAGE (5mm 5mm) (5mm 5mm)
MAX1233 MAX1234
TransZorb trademark General Semiconductor Industries, Inc. QSPI trademarks Motorola, Inc. MICROWIRE trademark National Semiconductor Corp. AutoShutdown trademark Maxim Integrated Products, Inc.
DACOUT
*BAT1
*BAT2
*AUX2
*AUX1
*PIN INCLUDES 8kV/15kV PROTECTION.
Maxim Integrated Products
pricing, delivery, ordering information, please contact Maxim/Dallas Direct! 1-888-629-4642, visit Maxim's website www.maxim-ic.com.
±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller MAX1233/MAX1234
ABSOLUTE MAXIMUM RATINGS
AVDD GND.-0.3V DVDD AVDD .-0.3V +0.3V Digital Inputs/Outputs .-0.3V (DVDD 0.3V) AUX1, AUX2, .-0.3V (AVDD 0.3V) BAT1, BAT2 .-0.3V Maximum 1000-4-2 (per STD-883 HBM) AUX1, AUX2, BAT1, BAT2.±15kV Other Pins.±2.5kV Maximum Current into Pin.50mA Continuous Power Dissipation +70°C) 28-Pin (derate 28.5mW/°C above +70°C) Operating Temperature Range .-40°C +85°C Storage Temperature Range .-60°C +150°C Lead Temperature (soldering, 10s) .+300°C
Stresses beyond those listed under "Absolute Maximum Ratings" cause permanent damage device. These stress ratings only, functional operation device these other conditions beyond those indicated operational sections specifications implied. Exposure absolute maximum rating conditions extended periods affect device reliability.
ELECTRICAL CHARACTERISTICS
(DVDD AVDD +2.7V +3.6V (MAX1233), DVDD AVDD +4.75V +5.25V (MAX1234), external reference VREF 2.5V (MAX1233), VREF 4.096V (MAX1234); fSCLK 10MHz, fSAMPLE 50ksps, 12-bit mode, 0.1µF capacitor REF, -40°C +85°C, unless otherwise noted. Typical values +25°C.)
PARAMETER ACCURACY (Note Resolution Missing Codes Relative Accuracy (Note Differential Nonlinearity Offset Error 12-bit mode 10-bit 8-bit modes 12-bit mode 10-bit 8-bit modes 12-bit mode 10-bit 8-bit modes 12-bit mode Gain Error (Note 10-bit mode 8-bit mode Total Unadjusted Error Offset Temperature Coefficient Gain Temperature Coefficient Channel-to-Channel Offset Channel-to-Channel Gain Matching Noise Including internal VREF Full-scale input MAX1233 AVDD DVDD +2.7V +3.6V MAX1234 AVDD DVDD 12-bit mode 10-bit 8-bit modes Software-programmable 8/10/12 ±0.8 ±0.5 ±0.8 ±0.5 ±0.5 ±0.5 ±0.5 ±0.5 ±0.5 ±0.4 ±0.4 ±0.1 ±0.1 ±0.4 ±0.3 ppm/°C ppm/°C µVRMS Bits Bits SYMBOL CONDITIONS ANALOG-TO-DIGITAL CONVERTER UNITS
Power-Supply Rejection
DYNAMIC SPECIFICATIONS (1kHz SINE WAVE, 2.5VP-P MAX1233, 4.096VP-P MAX1234, 50ksps, fSCLK 10MHz) Signal-to-Noise Plus Distortion SINAD
±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller
ELECTRICAL CHARACTERISTICS (continued)
(DVDD AVDD +2.7V +3.6V (MAX1233), DVDD AVDD +4.75V +5.25V (MAX1234), external reference VREF 2.5V (MAX1233), VREF 4.096V (MAX1234); fSCLK 10MHz, fSAMPLE 50ksps, 12-bit mode, 0.1µF capacitor REF, -40°C +85°C, unless otherwise noted. Typical values +25°C.)
PARAMETER Total Harmonic Distortion Spurious-Free Dynamic Range Full-Power Bandwidth Full-Linear Bandwidth CONVERSION RATE Internal Oscillator Frequency Aperture Delay Aperture Jitter Maximum Serial Clock Frequency Duty Cycle AUXILIARY ANALOG INPUTS (AUX1, AUX2) Input Voltage Range Input Leakage Current Input Capacitance BATTERY MONITOR INPUTS (BAT1, BAT2) Input Voltage Range Input Impedance Accuracy TEMPERATURE MEASUREMENT Temperature Range Resolution Accuracy INTERNAL REFERENCE Reference Output Voltage Output Tempco Reference Output Impedance Reference Short-Circuit Current EXTERNAL REFERENCE (INTERNAL REFERENCE DISABLED, REFERENCE APPLIED REF) Reference Input Voltage Range Input Impedance Input Current (Note VREF +2.5V 50ksps (MAX1233) VREF +4.096V 50ksps (MAX1234) Shutdown/between conversions ±0.1 VREF TCVREF Normal operation 2.5V mode, +25°C 1.0V mode, +25°C 2.470 0.980 2.500 1.000 2.530 1.020 ppm/°C Differential method (Note Single measurement method (Note Differential method (Note Single measurement method (Note Sampling battery Battery monitor Internal reference Channel selected conversion stopped ±0.1 VREF fSCLK 11.5 SYMBOL SFDR -3dB point SINAD 67dB CONDITIONS UNITS
MAX1233/MAX1234
±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller MAX1233/MAX1234
ELECTRICAL CHARACTERISTICS (continued)
(DVDD AVDD +2.7V +3.6V (MAX1233), DVDD AVDD +4.75V +5.25V (MAX1234), external reference VREF 2.5V (MAX1233), VREF 4.096V (MAX1234); fSCLK 10MHz, fSAMPLE 50ksps, 12-bit mode, 0.1µF capacitor REF, -40°C +85°C, unless otherwise noted. Typical values +25°C.)
PARAMETER ACCURACY Resolution Integral Linearity Error Differential Linearity Error Offset Error Offset Error Temperature Coefficient Full-Scale Error Full-Scale Error Temperature Coefficient DYNAMIC PERFORMANCE Voltage Output Slew Rate Output Settling Time Glitch Impulse Wake-Up Time OUTPUT Internal Reference Output Load Regulation Output Resistance VREFDAC (Note Code 255; 100µA Code 100µA Power-down mode TOUCH-SCREEN CONTROLLER On-Resistance Touch-Detection Internal Pullup Resistance Pullup Resistance Pulldown Resistance DIGITAL INPUTS (SCLK, DIN, Input Voltage Input Voltage High Input Leakage Current DVDD ±0.1 DVDD AVDD KEYPAD CONTROLLER (Note (Note DIGITAL INTERFACE 0.85 AVDD AVDD 0.95 AVDD Positive negative 0.5LSB; 50pF load (Note Code From shutdown V/µs nV/s Code 255, load Code 255, load (Note missing codes (Note SYMBOL CONDITIONS DIGITAL-TO-ANALOG CONVERTER ±1.0 ±1.0 Bits ppm/°C ppm/°C UNITS
±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller
ELECTRICAL CHARACTERISTICS (continued)
(DVDD AVDD +2.7V +3.6V (MAX1233), DVDD AVDD +4.75V +5.25V (MAX1234), external reference VREF 2.5V (MAX1233), VREF 4.096V (MAX1234); fSCLK 10MHz, fSAMPLE 50ksps, 12-bit mode, 0.1µF capacitor REF, -40°C +85°C, unless otherwise noted. Typical values +25°C.)
PARAMETER Input Capacitance DIGITAL OUTPUT (DOUT) Output Voltage Output Voltage High ISINK ISINK ISOURCE 1.5mA DVDD DVDD 4.75 CLOAD 50pF CLOAD 50pF CLOAD 50pF CLOAD 50pF (Note 5.25 SYMBOL CONDITIONS UNITS
MAX1233/MAX1234
DIGITAL OUTPUT (BUSY, PENIRQ, KEYIRQ, Output Voltage Output Voltage High ISINK 0.2mA ISOURCE 0.2mA POWER REQUIREMENTS Supply Voltage (Note AVDD DVDD IAVDD IDVDD MAX1233 MAX1234 Idle; blocks shut down Analog Digital Supply Current TIMING CHARACTERISTICS SCLK Clock Period SCLK Pulse Width High SCLK Pulse Width SCLK Rise Setup SCLK Rise Hold SCLK Fall DOUT Valid Fall DOUT Enabled Rise DOUT Disabled Fall SCLK Rise Fall SCLK Ignored SCLK Rise R_/C_ Data Valid Pulse Width High tDOV tDOD tCSS tCSH tGPO tCSW Only fSAMPLE 20ksps Only load Only internal reference
Note Tested DVDD AVDD +2.7V (MAX1233), DVDD AVDD (MAX1234). Note Relative accuracy deviation analog value code from theoretical value after offset gain errors have been removed. Note Offset nulled. Note Difference between TEMP1 TEMP2; temperature (VTEMP2 VTEMP1) 2680°K/V. calibration necessary. Note Temperature coefficient -2.1mV/°C. Determine absolute temperature extrapolating from calibrated value. Note performance limited conversion noise floor, typically 300µVP-P. external reference below 2.5V compromise performance. Note Guaranteed from code 255.
±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller MAX1233/MAX1234
ELECTRICAL CHARACTERISTICS (continued)
(DVDD AVDD +2.7V +3.6V (MAX1233), DVDD AVDD +4.75V +5.25V (MAX1234), external reference VREF 2.5V (MAX1233), VREF 4.096V (MAX1234); fSCLK 10MHz, fSAMPLE 50ksps, 12-bit mode, 0.1µF capacitor REF, -40°C +85°C, unless otherwise noted. Typical values +25°C.) Note Note Note Note Note Note offset value extrapolated from range over which guaranteed. Output settling time measured stepping from code 255, from code Actual output voltage full scale 255/256 VREFDAC. Resistance open when configured GPIO shutdown. AVDD DVDD should differ more than 300mV. When configured GPIO.
Timing Diagram
tCSW tCSS tCSH tCSH tCSS
SCLK
tDOV DOUT tDOD
R_/C_
NOTE: TIMING SCALE.
tGPO
±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller MAX1233/MAX1234
Typical Operating Characteristics
(AVDD DVDD (MAX1233) (MAX1234), external VREF +2.5V (MAX1233), external VREF +4.096V (MAX1234), fSCLK 10MHz (50% duty cycle), fSAMPLE 20ksps, CLOAD 50pF, 0.1µF capacitor REF, +25°C, unless otherwise noted.)
SHUTDOWN CURRENT ANALOG SUPPLY VOLTAGE
MAX1233/34 toc01
SHUTDOWN CURRENT TEMPERATURE
MAX1233/34 toc02
INTERNAL OSCILLATOR FREQUENCY ANALOG SUPPLY VOLTAGE
INTERNAL OSCILLATOR FREQUENCY (MHz) MAX1233/MAX1234
MAX1233/34 toc03
SHUTDOWN CURRENT (nA) AVDD
SHUTDOWN CURRENT (nA) TEMPERATURE (°C)
10.0
AVDD
INTERNAL OSCILLATOR FREQUENCY TEMPERATURE
MAX1233/34 toc04
TEMP1 DIODE VOLTAGE ANALOG SUPPLY VOLTAGE
MAX1233/34 toc05
TEMP1 DIODE VOLTAGE TEMPERATURE
0.75 TEMP1 DIODE VOLTAGE 0.70 0.65 0.60 0.55 0.50 0.45 0.40
MAX1233/34 toc06
INTERNAL OSCILLATOR FREQUENCY (MHz) TEMPERATURE (°C) MAX1233, AVDD +3.0V MAX1234, AVDD +5.0V
0.70 0.68 TEMP1 DIODE VOLTAGE 0.66 0.64 0.62 0.60 0.58 0.56 0.54 0.52 0.50
0.80
AVDD
TEMPERATURE (°C)
TEMP2 DIODE VOLTAGE ANALOG SUPPLY VOLTAGE
MAX1233/34 toc07
TEMP2 DIODE VOLTAGE TEMPERATURE
MAX1233/34 toc08
0.80
0.90 0.85 TEMP2 DIODE VOLTAGE 0.80 0.75 0.70 0.65
TEMP2 DIODE VOLTAGE
0.75
0.70
0.65
0.60 AVDD
0.60 TEMPERATURE (°C)
±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller MAX1233/MAX1234
Typical Operating Characteristics (continued)
(AVDD DVDD (MAX1233) (MAX1234), external VREF +2.5V (MAX1233), external VREF +4.096V (MAX1234), fSCLK 10MHz (50% duty cycle), fSAMPLE 20ksps, CLOAD 50pF, 0.1µF capacitor REF, +25°C, unless otherwise noted.)
INTEGRAL NONLINEARITY OUTPUT CODE
MAX1233/34 toc09
DIFFERENTIAL NONLINEARITY OUTPUT CODE
(LSB) -0.2 -0.4 -0.6 -0.8 -1.0
MAX1233/34 toc10
(LSB) -0.2 -0.4 -0.6 -0.8 -1.0 1000 1500 2000 2500 3000 3500 4000 OUTPUT CODE
1000 1500 2000 2500 3000 3500 4000 OUTPUT CODE
OFFSET ERROR ANALOG SUPPLY VOLTAGE
MAX1233/34 toc11
OFFSET ERROR TEMPERATURE
OFFSET ERROR (LSB) -0.5 -1.0 -1.5 -2.0
MAX1233/34 toc12
OFFSET ERROR (LSB) -0.5 -1.0 -1.5 -2.0
AVDD
TEMPERATURE (°C)
GAIN ERROR ANALOG SUPPLY VOLTAGE
MAX1233/34 toc13
GAIN ERROR TEMPERATURE
GAIN ERROR (LSB) -0.5 -1.0 -1.5 -2.0
MAX1233/34 toc14
GAIN ERROR (LSB) -0.5 -1.0 -1.5 -2.0 AVDD
TEMPERATURE (°C)
±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller MAX1233/MAX1234
Typical Operating Characteristics (continued)
(AVDD DVDD (MAX1233) (MAX1234), external VREF +2.5V (MAX1233), external VREF +4.096V (MAX1234), fSCLK 10MHz (50% duty cycle), fSAMPLE 20ksps, CLOAD 50pF, 0.1µF capacitor REF, +25°C, unless otherwise noted.)
EXTERNAL REFERENCE INPUT CURRENT SAMPLING RATE
MAX1233 VREF +2.5V REFERENCE CURRENT (µA)
MAX1233/34 toc15
SUPPLY CURRENT SAMPLING RATE
MAX1233/34 toc16
1000
SUPPLY CURRENT (µA)
fSAMPLE (Hz) 100k
100k fSAMPLE (Hz)
SUPPLY CURRENT SUPPLY VOLTAGE
MAX1233/34 toc17
SUPPLY CURRENT TEMPERATURE
AVDD SUPPLY CURRENT (µA)
MAX1233/34 toc18
EXTERNAL fSAMPLE 20ksps SUPPLY CURRENT (µA)
AVDD
TEMPERATURE (°C)
INTEGRAL NONLINEARITY CODE
MAX1233/34 toc19
DIFFERENTIAL NONLINEARITY OUTPUT CODE
MAX1233/34 toc20
0.075 0.050 0.025 (LSB) -0.025 -0.050 -0.075 -0.100 CODE
0.075 0.050 0.025 (LSB) -0.025 -0.500 -0.075 -0.100
OUTPUT CODE
±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller MAX1233/MAX1234
Typical Operating Characteristics (continued)
(AVDD DVDD (MAX1233) (MAX1234), external VREF +2.5V (MAX1233), external VREF +4.096V (MAX1234), fSCLK 10MHz (50% duty cycle), fSAMPLE 20ksps, CLOAD 50pF, 0.1µF capacitor REF, +25°C, unless otherwise noted.)
FULL-SCALE ERROR ANALOG SUPPLY VOLTAGE
0.75 0.50 FULL-SCALE ERROR (LSB) 0.25 -0.25 -0.50 -0.75 AVDD
MAX1233/34 toc21
FULL-SCALE ERROR TEMPERATURE
FULL-SCALE ERROR (LSB) FULL-SCALE ERROR -0.4 -0.8 -1.2 0.75 0.50 0.25 -0.25 -0.50 -0.75 TEMPERATURE (°C)
MAX1233/34 toc22
-0.4 -0.8 -1.2 FULL-SCALE ERROR VREF
SUPPLY CURRENT ANALOG SUPPLY VOLTAGE
MAX1233/34 toc23
SUPPLY CURRENT TEMPERATURE
SUPPLY CURRENT (µA)
MAX1233/34 toc24
SUPPLY CURRENT (µA)
AVDD
TEMPERATURE (°C)
REFERENCE VOLTAGE ANALOG SUPPLY VOLTAGE
2.550
MAX1233/34 toc25
REFERENCE VOLTAGE TEMPERATURE
1.020 2.60
MAX1233/34 toc26
1.250
2.525 VREF VREF 1.0V 2.500 VREF 2.5V 2.475
1.010 VREF VREF
2.55 VREF 1.0V
1.125
1.000
2.50
1.000
0.990
2.45
VREF 2.5V
0.875
2.450 AVDD
0.980
2.40
0.750 TEMPERATURE (°C)
±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller MAX1233/MAX1234
Typical Operating Characteristics (continued)
(AVDD DVDD (MAX1233) (MAX1234), external VREF +2.5V (MAX1233), external VREF +4.096V (MAX1234), fSCLK 10MHz (50% duty cycle), fSAMPLE 20ksps, CLOAD 50pF, 0.1µF capacitor REF, +25°C, unless otherwise noted.) REFERENCE SUPPLY CURRENT ANALOG SUPPLY VOLTAGE
MAX1233/34 toc27
REFERENCE SUPPLY CURRENT TEMPERATURE
MAX1233/34 toc28
SUPPLY CURRENT (µA)
SUPPLY CURRENT (µA)
AVDD
TEMPERATURE (°C)
Description
NAME DVDD AVDD XYGND BAT1 BAT2 AUX1 AUX2 FUNCTION Positive Digital Supply Voltage, +2.7V +3.6V MAX1233, +4.75V +5.25V MAX1234. Bypass with 0.1µF capacitor. Must within 300mV AVDD. Positive Analog Supply Voltage, +2.7V +3.6V MAX1233, +4.75V +5.25V MAX1234. Bypass with 0.1µF capacitor. Must within 300mV DVDD. Position Input Position Input Position Input Position Input Analog Digital Ground Battery Monitoring Input Measures battery voltages Battery Monitoring Input Measures battery voltages Auxiliary Analog Input ADC. Measures analog voltages from zero VREF. Auxiliary Analog Input ADC. Measures analog voltages from zero VREF. Voltage Reference Output/Input. Reference voltage analog-to-digital conversion. internal reference mode, reference buffer provides 2.5V 1.0V nominal output. external reference mode, apply reference voltage between 1.0V AVDD. Bypass with 0.1µF capacitor external reference mode only. Voltage Output; AVDD Full Scale Keypad reconfigured GPIO3. Keypad reconfigured GPIO2. Keypad reconfigured GPIO1. Keypad reconfigured GPIO0. Keypad Column reconfigured GPIO4.
DACOUT
±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller MAX1233/MAX1234
Description (continued)
NAME KEYIRQ PENIRQ DOUT BUSY SCLK FUNCTION Keypad Column reconfigured GPIO5. Keypad Column reconfigured GPIO6. Keypad Column reconfigured GPIO7. Active-Low Keypad Interrupt. KEYIRQ when press detected. Active-Low Touch Interrupt. PENIRQ when screen touch detected. Serial Data Output. Data clocked SCLK falling edge. High impedance when high. Active-Low Busy Output. BUSY goes stays during each functional operation. host controller should wait until BUSY high again before using serial interface. Serial Data Input. Data clocked rising edge SCLK. Active-Low Chip Select. Data clocked into unless low. When high, DOUT high impedance. Serial Clock Input. Clocks data serial interface sets conversion speed (duty cycle must 70%).
*ESD protected: ±8kV Contact, ±15kV Air.
Detailed Description
MAX1233/MAX1234 4-wire touch-screen controllers. Figure shows functional diagram MAX1233/MAX1234. Each device includes 12-bit sampling ADC, 8-bit voltage output DAC, keypad scanner that also configured GPIO, internal clock, reference, temperature sensor, battery monitor inputs, auxiliary analog inputs, SPI/QSPI/ MICROWIRE-compatible serial interface, onresistance switches driving touch screens. 16-bit register inside MAX1233/MAX1234 allows easy control stores results that read time. BUSY output indicates that functional operation progress. PENIRQ KEYIRQ outputs, respectively, indicate that screen touch press occurred.
open floating. point where touch screen pressed brings resistive layers contact creates voltage-divider that point. data converter senses voltage point contact through input digitizes
12-Bit
Analog Inputs Figure shows block diagram ADC's analog input section including input multiplexer, differential input, differential reference. input multiplexer switches between AUX1, AUX2, BAT1, BAT2, internal temperature sensor. time required acquire input signal function quickly input capacitance charged. input signal's source impedance high, acquisition time lengthens, more time must allowed. acquisition time (tACQ) maximum time device takes acquire input signal 12bit accuracy. Configure tACQ writing control register. Table maximum input signal source impedance (RSOURCE) complete settling during acquisition. Accommodate higher source impedances placing 0.1µF capacitor between analog input GND. Input Bandwidth ADC's input-tracking circuitry 0.5MHz smallsignal bandwidth. avoid high-frequency signals being aliased into frequency band interest, antialias filtering recommended.
Touch-Screen Operation
4-wire touch-screen controller works creating voltage gradient across vertical horizontal resistive touch screen connected analog inputs MAX1233/MAX1234, shown Figure voltage across touch-screen panels applied through internal MOSFET switches that connect each resistive layer AVDD ground. example, measure position when pointing device presses touch screen, drivers turned connecting side vertical resistive layer AVDD other side ground. horizontal resistive layer functions sense line. side this resistive layer gets connected input, while other side left
±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller MAX1233/MAX1234
OSCILLATOR
KEYPAD CONTROLLER GPIO
MAX1233 MAX1234
REGISTERS SCAN STATE CONTROL TEMP SENSOR
*XX/Y SWITCHES *YMUX 12-BIT BATTERY MONITOR BATTERY MONITOR SERIAL DATA
DOUT SCLK PENIRQ KEYIRQ
*BAT1
BUSY
*BAT2 *AUX1 *AUX2
INTERNAL REFERENCE 2.5V/1.0V 8-BIT
DACOUT
*ESD PROTECTED
Figure Block Diagram
+AVDD
Table Maximum Input Source Impedance
ACQUISITION RESOLUTION TIME (µs) (BITS) MAXIMUM RSOURCE COMPLETE SETTLING DURING ACQUISITION
FORCE LINE
SENSE LINE
SENSE LINE
+REF -REF
FORCE LINE
Figure Touch-Screen Measurement
±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller MAX1233/MAX1234
+AVDD VREF
TEMP2
TEMP1
MAX1233 MAX1234
XREF ON/OFF
Y+IN
+REF CONVERTER 2.5V/1.0V REFERENCE -REF
7.5k VBAT1 7.5k VBAT2 2.5k 2.5k
BATTERY AUX1 AUX2
BATTERY
Figure Simplified Diagram Analog Input Section
Analog Input Protection Internal protection diodes that clamp analog input AVDD allow analog input pins swing from 0.3V 0.3V without damage. Analog inputs must exceed more than 50mV lower than more than 50mV accurate conversions. off-channel analog input voltage exceeds supplies, limit input current 50mA. analog inputs also fully protected
±8kV, using Contact-Discharge method ±15kV using Air-Gap method specified IEC1000-4-2.
Reference
Internal Reference MAX1233/MAX1234 offer internal voltage reference that +1.0V +2.5V. MAX1233/MAX1234 typically internal reference battery monitoring, temperature measurement,
±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller MAX1233/MAX1234
ment, temperature measurement, auxiliary input measurement written control register, device powers internal reference, waits internal reference settle, completes requested scan, powers down internal reference. reference power delay depends upon resolution selected (see Table bypass with external capacitor when performing scans auto power-down mode. Full-Power Mode (RES1 RES0 full-power mode, RES1 RES0 HIGH. this mode, device powered internal reference always MAX1233/MAX1234 internal reference remains fully powered after completing scan.
+1.25V BANDGAP OPTIONAL
Figure Block Diagram Internal Reference
measurement auxiliary inputs. Figure shows on-chip reference circuitry MAX1233/MAX1234. internal reference voltage writing bits control register (see Tables 12). MAX1233/MAX1234 accept external reference connected conversion. External Reference MAX1233/MAX1234 accept external reference connected conversions. internal reference should disabled (RES1 when using external reference. conversion rate 50ksps, external reference must deliver 15µA load current have less output impedance. external reference high output impedance noisy, bypass close with 0.1µF capacitor. Selecting Internal External Reference type reference being used programming control register. select internal reference, clock zeros into bits [A/D3:A/D0] zero RES1, shown Control Registers section. change external reference mode, clock zeros into bits [A/D3:A/D0] RES1. Table more information about selecting internal external reference ADC.
Internal Clock
MAX1233/MAX1234 operate from internal oscillator, which accurate within 10MHz specified clock rate. internal oscillator controls timing acquisition, conversion, touch-screen settling, reference power-up, keypad debounce times.
8-Bit
MAX1233/MAX1234 have voltage-output, true 8-bit monotonic with less than 1LSB integral nonlinearity error less than 1LSB differential nonlinearity error. requires supply current only 150µA (typ) provides buffered voltage output. midscale code power-up remains there until code written register. During shutdown, DAC's output pulled ground with load. internal used various system applications such LCD/TFT-bias control, automatic tuning (VCO), power amplifier bias control, programmable threshold levels, automatic gain control (AGC). 8-bit MAX1233/MAX1234 employs current-steering topology shown Figure core this reference voltage-to-current converter (V/I) that generates reference current. This current mirrored equally weighted current sources. switches control outputs these current mirrors that only desired fraction total current-mirror currents steered output. current then converted voltage across resistor, output amplifier buffers this voltage. Output Voltage 8-bit code binary unipolar with 1LSB (VREF/256). full-scale output voltage (0.9 AVDD 1LSB).
Reference Power Modes
Auto Power-Down Mode (RES1 RES0 MAX1233/MAX1234 auto power-down mode initial power-up. RES1 RES0 bits zero MAX1233/MAX1234 auto power-down mode. this mode, internal reference normally off. When command perform battery measure-
±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller MAX1233/MAX1234
+AVDD VREF SW255 TOUCH-SCREEN DETECTOR PENIRQ
TOUCH SCREEN
Figure Current-Steering Topology
Output Buffer voltage output internally buffered unitygain follower that slews ±0.4V/µs. output swing from zero full scale. With 1/4FS 3/4FS output transition, amplifier output typically settles 1/2LSB less than when loaded with parallel with 50pF. buffer amplifier stable with combination resistive loads >10k capacitive loads <50pF. Power-On Reset registers MAX1233/MAX1234 power default zero state, except data register, which 10000000, output midscale.
Figure Touch-Screen Detection Block Diagram
Keypad Controller GPIO
keypad controller designed interface matrixtype rows columns keys fewer) keypad host controller. control register controls keypad interrupt, keypad scan, keypad debounce times. KeyMask ColumnMask registers enable masking particular entire column keypad when they use. MAX1233/MAX1234 offer keypad data registers. KPData1 holds keypad scan results, including masked data, thus pending register. KPData2 holds keypad scan results only unmasked keys. fewer keys being monitored, more row/column pins MAX1233/MAX1234 software programmed GPIO pins.
internally pulled through resistor shown Figure When screen touched, pulled through touch screen touch detected. When pullup resistor first connected, floating near ground. prevent false touch detection this case, precharged high 0.1µs using PMOS driver before touch detection begins.
Key-Press Detection
Key-press detection enabled disabled writing keypad control register shown Table Key-press detection disabled initial power-up. Once key-press detection enabled, pins internally connected DVDD pins internally pulled through resistor. When pressed, associated pulled DVDD press detected. Figure shows key-press detection circuitry.
Touch-Screen Detection
Touch-screen detection enabled disabled writing control register shown Table Touch-screen detection disabled initial power-up. Once touch-screen detection enabled, driver connected GND.
Interrupts
Interrupt Request (PENIRQ) PENIRQ output used alert host controller screen touch. PENIRQ output normally
±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller MAX1233/MAX1234
SIMPLIFIED KEYPAD CIRCUITRY
DRIVERS PULL HIGH THREE-STATE
KEYPAD WAKEUP DEBOUNCE LOGIC
KEYPAD
Figure Key-Press Detection Circuitry
PENIRQ
PENIRQ
BUSY
BUSY
DATA READ
DATA READ DOUT TOUCHSCREEN DATA
DOUT
TOUCHSCREEN DATA
Figure Timing Diagram Touch-Initiated Screen Scan
Figure Timing Diagram Host-Initiated Screen Scan
±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller MAX1233/MAX1234
high goes after screen touch detected. PENIRQ returns high only after touch-screen scan completed. PENIRQ does again until touch-screen data registers read. Figures show timing diagrams PENIRQ pin. Keypad Interrupt Request (KEYIRQ) KEYIRQ output used alert host controller press. KEYIRQ output normally high goes after press detected. KEYIRQ returns high only after key-press scan completed. KEYIRQ does again until key-press data registers read. Figures show timing diagrams KEYIRQ pin.
KEYIRQ
BUSY
DATA READ DOUT
Busy Indicator (BUSY)
BUSY informs host processor that scan progress. BUSY normally high goes stays during each functional operation. host controller should wait until BUSY high again before using serial interface.
TOUCHSCREEN DATA
Figure Timing Diagram Key-Press-Initiated Debounce Scan
Digital Interface
MAX1233/MAX1234 interface host controller through standard 3-wire serial interface 10MHz. digital inputs MAX1233/MAX1234. DOUT serial data output. Data clocked SCLK falling edge high impedance when high. PENIRQ KEYIRQ communicate interrupts from touch-screen keypad controllers host processor when screen touch press detected. BUSY informs host processor that scan progress. addition these digital I/Os, column pins keypad controller programmed GPIO pins. Communications Protocol MAX1233/MAX1234 controlled reading from writing registers through 3-wire serial interface. These registers addressed through 16-bit command that sent prior data. command shown Table first bits after falling edge contain command word. command word begins with bit, which specifies direction data flow serial bus. Bits through reserved future use. specifies page memory which desired register located. last bits specify
KEYIRQ
BUSY
DATA READ
DOUT
TOUCHSCREEN DATA
Figure Timing Diagram Host-Initiated Keypad Debounce Scan
address desired register. next bits data read from written address specified command word. After clock cycles, interface automatically increments address pointer continues reading writing until rising edge until reaches page.
Table Command Word Format
BIT15 BIT14 BIT13 BIT12 BIT11 BIT10 BIT9 BIT8 BIT7 BIT6 PAGE BIT5 ADD5 BIT4 ADD4 BIT3 ADD3 BIT2 ADD2 BIT1 ADD1 BIT0 ADD0
±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller MAX1233/MAX1234
Table Register Summary MAX1233/MAX1234
PAGE ADDR (HEX) REGISTER NAME BIT15 BIT14 BIT13 BIT12 BIT11 BIT10 BIT9 BIT8 BIT7 BIT6 BIT5 BIT4 BIT3 BIT2 BIT1 BIT0
BAT1 BAT2 AUX1 AUX2 TEMP1 TEMP2 Reserved Reserved Reserved GPIO GPD7 GPD6 GPD5 KPData1 K1_15 K1_14 K1_1 KPData2 K2_15 K2_14 K2_1 Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved PENSTS ADSTS A/D3 KEYSTS1 KEYSTS0 DBN2 DAPD Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved GPIO Pullup GPIO KPKeyMask KM15 KM14 KM13 KPColumn Mask Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved
GPD4 K1_1 K2_1 A/D2 DBN1
Z1_11 Z2_11 B1_11 B2_11 A1_11 A2_11 T1_11 T2_11 GPD3 K1_11 K2_11 A/D1 DBN0
Z1_10 Z2_10 B1_10 B2_10 A1_10 A2_10 T1_10 T2_10 GPD2 K1_10 K2_10 A/D0 HLD2 KM10
Z1_9 Z2_9 B1_9 B2_9 A1_9 A2_9 T1_9 T2_9 GPD1 K1_9 K2_9 RES1 HLD1
Z1_8 Z2_8 B1_8 B2_8 A1_8 A2_8 T1_8 T2_8 GPD0 K1_8 K2_8 RES0 HLD0
Z1_7 Z2_7 B1_7 B2_7 A1_7 A2_7 T1_7 T2_7 K1_7 K2_7 AVG1
Z1_6 Z2_6 B1_6 B2_6 A1_6 A2_6 T1_6 T2_6 K1_6 K2_6 AVG2
Z1_5 Z2_5 B1_5 B2_5 A1_5 A2_5 T1_5 T2_5 K1_5 K2_5 CNR1
Z1_4 Z2_4 B1_4 B2_4 A1_4 A2_4 T1_4 T2_4 K1_4 K2_4 CNR0
Z1_3 Z2_3 B1_3 B2_3 A1_3 A2_3 T1_3 T2_3 K1_3 K2_3
Z1_2 Z2_2 B1_2 B2_2 A1_2 A2_2 T1_2 T2_2 K1_2 K2_2
Z1_1 Z2_1 B1_1 B2_1 A1_1 A2_1 T1_1 T2_1 K1_1 K2_1
Z1_0 Z2_0 B1_0 B2_0 A1_0 A2_0 T1_0 T2_0 K1_0 K2_0
KM12 KM11
±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller MAX1233/MAX1234
order read entire first page memory, example, host processor must send MAX1233/MAX1234 command 0x8000 MAX1233/MAX1234 then begin clocking 16-bit data starting with X-data register. order write second page memory, host processor sends MAX1233/MAX1234 command 0x0040H. succeeding data then written 16-bit words beginning with control register. Figures show complete write read operation, respectively, between processor MAX1233/MAX1234. Memory MAX1233/MAX1234s' internal memory divided into pages-one data control, each which contains thirty-two 16-bit registers.
Control Registers
Table provides summary registers locations MAX1233/MAX1234. Control Register measures touch position, touch pressure, battery voltage, auxiliary analog inputs, temperature. control register determines which input selected converted. Tables show format descriptions control register.
SCLK
WRITE OPERATION
READ/WRITE WRITE
D15-D0 COMMAND WORD
D15-D0 DATA WORD
DOUT
THREESTATE
THREESTATE
TIMING SCALE.
Figure 10a. Timing Diagram Write Operation
SCLK
READ OPERATION
D15-D0 COMMAND WORD
DOUT THREE-STATE
DATA WORD
DATA WORD
THREE-STATE
Figure 10b. Timing Diagram Read Operation
Table Control Register
BIT15 PENSTS BIT14 ADSTS BIT13 BIT12 BIT11 BIT10 A/D3 A/D2 A/D1 A/D0 BIT9 RES1 BIT8 RES0 BIT7 AVG1 BIT6 AVG0 BIT5 BIT4 BIT3 BIT2 BIT1 BIT0 CNR1 CNR0
±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller
Bits 14-15: Interrupt Status Status Bits These bits used control monitor scans. Bits 10-13: Scan Select These bits control which input convert which converter mode used. bits identical regardless read write. Table details about using these bits. Bits 8-9: Resolution Control These bits specify resolution identical regardless read write. Table shows these bits resolution. Bits 6-7: Converter Averaging Control These bits specify number data averages converter performs. Table shows program desired number averages. When averaging used, ADSTS BUSY indicate converter busy until conversions needed averaging finish. These bits identical, regardless read write. Bits 4-5: Conversion Rate Control These bits specify internal conversion rate, which uses perform single conversion, shown Table Lowering conversion rate also reduces power consumption. These bits identical, regardless read write.
MAX1233/MAX1234
Table Control Register Descriptions
(MSB) (LSB) NAME PENSTS ADSTS A/D3 A/D2 A/D1 A/D0 RES1 RES0 AVG1 AVG0 CNR1 CNR0 Read: status; Write: stops Selects scan functions Selects scan functions Selects scan functions Selects scan functions Controls resolution Controls resolution Controls result averaging Controls result averaging Controls conversion rate Controls conversion rate Controls touch-screen settling wait time Controls touch-screen settling wait time Controls touch-screen settling wait time Chooses 1.0V 2.5V reference DESCRIPTION Read: interrupt status; Write: sets interrupt initiated touch-screen scans
Table ADSTS Operation
PENSTS ADSTS READ FUNCTION screen touch detected; scan conversion progress Screen touch detected; scan conversion progress screen touch detected; data available Screen touch detected; data available WRITE FUNCTION Performs scan waits detect screen touch. Upon detection, issues interrupt waits until told scan host controller. Stops ongoing scan waits detect screen touch. Upon detection, issues interrupt performs scan. Stops ongoing scan waits detect screen touch. Upon detection, issues interrupt waits until told scan host controller. Stops ongoing scan powers down screen touch detection circuit. screen touches detected this mode.
±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller MAX1233/MAX1234
Table Scan Select (Touch Screen, Battery, Auxiliary Channels, Temperature)
A/D3 A/D2 A/D1 A/D0 FUNCTION Configures reference selected [1:0] bits shown Table measurement performed. Measures touch position returns results data registers. Measures touch position touch pressure returns results data registers. Measures touch position returns results data register. Measures touch position returns results data register. Measures Z1/Z2 touch pressure returns results data register. Measures Battery Input returns results BAT1 data register. Measures Battery Input returns results BAT2 data register. Measures Auxiliary Input returns results AUX1 data register. Measures Auxiliary Input returns results AUX2 data register. Measures temperature (single ended) returns results TEMP1 data register. Measures Battery Input Battery Input Auxiliary Input Auxiliary Input temperature (differential), returns results appropriate data registers. Measures temperature (differential) returns results TEMP1 TEMP2 data registers. Turns drivers. measurement performed. Turns drivers. measurement performed. Turns drivers. measurement performed.
Table Resolution Control
RES1 RES0 RESOLUTION INTERNALLY TIMED REFERENCE POWER-UP DELAY* (µs)
Table Conversion Rate Control
CNR1 CNR0 FUNCTION 3.5µs/sample (1.5µs acquisition, conversion) 3.5µs/sample (1.5µs acquisition, conversion) 10µs/sample (5µs acquisition, conversion) 100µs/sample (95µs acquisition, conversion)
*Applicable only temperature, battery, auxiliary measurements auto power-up reference mode.
Table Averaging Control
AVG1 AVG0 FUNCTION data averages (default) data averages data averages data averages
±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller
Bits 1-3: Touch-Screen Settling Time Control These bits specify time delay from pen-touch detection conversion start. This allows selection appropriate settling time touch screen being used. Table shows settling time. These bits identical, regardless read write. Internal Reference Voltage Control This selects internal reference voltage, either +1.0V +2.5V. This identical, regardless read write. reference control shown Table Internal Reference Power-Down Control control register controls power setting internal reference. Zeros must written bits A/D3-A/D0 control internal reference power-up followed appropriate logic RES1 RES0 bits. Table shows internal reference power-down control. Control Register this control register determines powerdown control on-board DAC. Table shows control register. Writing zero (DAPD) powers DAC, while writing powers down DAC. Table describes control register contents, while Table shows power-down bit. Keypad Control Registers keypad control register, keypad mask register, keypad column mask control register control keypad scanner MAX1233/MAX1234. keypad control register (Table controls scanning debouncing, while keypad mask register (Table keypad column mask control register (Table 24),
MAX1233/MAX1234
Table Touch-Screen Settling Time Control*
SETTLING TIME Settling time: Settling time: 100µs Settling time: 500µs Settling time: Settling time: Settling time: 10ms Settling time: 50ms Settling time: 100ms
Table Control Register Descriptions
(MSB) [14:0] NAME DAPD DESCRIPTION powered down Reserved
*Applicable only measurements.
Table Reference Control
FUNCTION +1.0V reference +2.5V reference
Table Power-Down
DAPC FUNCTION powered powered down
Table Internal Reference Auto Power-Up Control
RES1 RES0 REFERENCE SOURCE Internal Internal External External REFERENCE POWER MODE Power wait reference settle, power down again each temperature, battery, auxiliary scan (auto power-up mode) Always powered Always powered down Always powered down
Table Control Register
BIT15 DAPD BIT14 BIT13 BIT12 BIT11 BIT10 BIT9 BIT8 BIT7 BIT6 BIT5 BIT4 BIT3 BIT2 BIT1 BIT0
±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller MAX1233/MAX1234
Table Keypad Control Register
BIT15 KEYSTS1 BIT14 BIT13 BIT12 DBN1 BIT11 DBN0 BIT10 HLD2 BIT9 BIT8 BIT7 BIT6 BIT5 BIT4 BIT3 BIT2 BIT1 BIT0 KEYSTS0 DBN2
Table Keypad Control Register Description
(MSB) [7:0] NAME KEYSTS1 KEYSTS0 DBN2 DBN1 DBN0 HLD2 HLD1 HLD0 DESCRIPTION Read: keypad interrupt status; Write: interrupt initiated keypad scans Read: keypad scan status; Write: stop keypad scan Keypad debounce time control Keypad debounce time control Keypad debounce time control Keypad hold time control Keypad hold time control Keypad hold time control Reserved
Table KEYSTS1/KEYSTS0 Functions
KEYSTS1 KEYSTS0 READ FUNCTION button press detected; scan debounce progress Button press detected; scan debounce progress button press detected; data available Button press detected; data available WRITE FUNCTION Scans keypad once waits detect button press. Upon detection, issues interrupt waits host's instruction before scanning. Stops ongoing scan waits detect button press. Upon detection, issues interrupt scans keypad. Stops ongoing scan waits detect button press. Upon detection, issues interrupt waits host's instruction before scanning. Stops ongoing scan powers down button press detection circuit. button presses detected this mode.
Table Keypad Debounce Time Control
DBN2 DBN1 DBN0 FUNCTION (ms) Debounce time: Debounce time: Debounce time: Debounce time: Debounce time: Debounce time: Debounce time: Debounce time:
±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller
allowing certain keys masked from detection. Tables 18-21 show programmable bits keypad control register. Tables show programmable bits keypad mask registers. Keypad Controller GPIO section provides more details. GPIO Control Register GPIO control register GPIO pullup register allow keypad controller's column inputs configured eight parallel pins. Tables show GPIO control register layout control register descriptions. Tables show GPIO pullup disable register associated descriptions. more information, Applications Information section.
MAX1233/MAX1234
Table Keypad Hold Time Control
HLD2 HLD1 HLD0 FUNCTION button held, wait 100µs before beginning next debounce scan button held, wait debounce time before beginning next debounce scan button held, wait debounce times before beginning next debounce scan button held, wait debounce times before beginning next debounce scan button held, wait debounce times before beginning next debounce scan button held, wait debounce times before beginning next debounce scan button held, wait debounce times before beginning next debounce scan button held, wait debounce times before beginning next debounce scan
Table Keypad Mask Control Register
BIT15 KM15 BIT14 KM14 BIT13 KM13 BIT12 KM12 BIT11 KM11 BIT10 KM10 BIT9 BIT8 BIT7 BIT6 BIT5 BIT4 BIT3 BIT2 BIT1 BIT0
Table Keypad Mask Control Register Descriptions-Individual Mask
NAME KM15 KM14 KM13 KM12 KM11 KM10 DESCRIPTION Mask status register data update individual column Mask status register data update individual column Mask status register data update individual column Mask status register data update individual column Mask status register data update individual column Mask status register data update individual column Mask status register data update individual column Mask status register data update individual column Mask status register data update individual column Mask status register data update individual column Mask status register data update individual column Mask status register data update individual column Mask status register data update individual column Mask status register data update individual column Mask status register data update individual column Mask status register data update individual column
Table Keypad Column Mask Control Register
BIT15 BIT14 BIT13 BIT12 BIT11 BIT10 BIT9 BIT8 BIT7 BIT6 BIT5 BIT4 BIT3 BIT2 BIT1 BIT0
±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller MAX1233/MAX1234
Table Keypad Column Mask Control Register Descriptions
[11:0] NAME DESCRIPTION Mask interrupt, status register, pending register data update keys column Mask interrupt, status register, pending register data update keys column Mask interrupt, status register, pending register data update keys column Mask interrupt, status register, pending register data update keys column Reserved
Table GPIO Control Register
BIT15 BIT14 BIT13 BIT12 BIT11 BIT10 BIT9 BIT8 BIT7 BIT6 BIT5 BIT4 BIT3 BIT2 BIT1 BIT0
Table GPIO Control Register Descriptions
[7:0] NAME [OE7:OE0] DESCRIPTION becomes GPIO becomes GPIO becomes GPIO becomes GPIO becomes GPIO becomes GPIO becomes GPIO becomes GPIO GPIO configured output remains keypad column remains keypad column remains keypad column remains keypad column remains keypad remains keypad remains keypad remains keypad GPIO configured input
Table GPIO Pullup Disable Register
BIT15 BIT14 BIT13 BIT12 BIT11 BIT10 BIT9 BIT8 BIT7 BIT6 BIT5 BIT4 BIT3 BIT2 BIT1 BIT0
Table GPIO Pullup Disable Register Descriptions
[15:8] [7:0] NAME DESCRIPTION Pullup disabled. Open collector output. [PU7:PU0] Pullup enabled. Reserved
Analog Input Data Registers Table shows format BAT1, BAT2, AUX1, AUX2, TEMP1, TEMP2 data registers. data format these registers right justified beginning with Data written through serial interface these registers stored. Keypad Data Registers Table shows formatting keypad data registers, while Tables provide individual register descriptions. These registers have same format keypad mask register. Each represents keypad. Table shows 16-key keypad. Data written through serial interface these registers stored.
Data Registers data results from conversions keypad scans held data registers MAX1233/MAX1234. During power-up, these data registers with exception data register default 0000H. register defaults 1000H.
±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller MAX1233/MAX1234
Table Analog Inputs Data Register Format
REGISTER BIT15 BIT14 BIT13 BIT12 BIT11 BIT10 BIT9 NAME BATT1 BATT2 AUX1 AUX2 TEMP1 TEMP2 BIT8 Z1_8 Z2_8 B1_8 B2_8 A1_8 A2_8 T1_8 T2_8 BIT7 Z1_7 Z2_7 B1_7 B2_7 A1_7 A2_7 T1_7 T2_7 BIT6 Z1_6 Z2_6 B1_6 B2_6 A1_6 A2_6 T1_6 T2_6 BIT5 Z1_5 Z2_5 B1_5 B2_5 A1_5 A2_5 T1_5 T2_5 BIT4 Z1_4 Z2_4 B1_4 B2_4 A1_4 A2_4 T1_4 T2_4 BIT3 Z1_3 Z2_3 B1_3 B2_3 A1_3 A2_3 T1_3 T2_3 BIT2 Z1_2 Z2_2 B1_2 B2_2 A1_2 A2_2 T1_2 T2_2 BIT1 Z1_1 Z2_1 B1_1 B2_1 A1_1 A2_1 T1_1 T2_1 BIT0 Z1_0 Z2_0 B1_0 B2_0 A1_0 A2_0 T1_0 T2_0
Z1_11 Z1_10 Z1_9 Z2_11 Z2_10 Z2_9 B1_11 B1_10 B1_9 B2_11 B2_10 B2_9 A1_11 A1_10 A1_9 A2_11 A2_10 A2_9 T1_11 T1_10 T1_9 T2_11 T2_10 T2_9
Table Keypad Data Registers
REGISTER BIT15 BIT14 BIT13 BIT12 BIT11 BIT10 BIT9 NAME KPData1 KPData2 K1_15 K1_14 K1_13 K1_12 K1_11 K1_10 K1_9 K2_15 K2_14 K2_13 K2_12 K2_11 K2_10 K2_9 BIT8 K1_8 K2_8 BIT7 K1_7 K2_7 BIT6 K1_6 K2_6 BIT5 K1_5 K2_5 BIT4 K1_4 K2_4 BIT3 K1_3 K2_3 BIT2 K1_2 K2_2 BIT1 K1_1 K2_1 BIT0 K1_0 K2_0
Table Keypad Data Register Descriptions
NAME DESCRIPTION Keypad scan result column only masked column mask. Keypad scan result column only masked column mask. Keypad scan result column only masked column mask. Keypad scan result column only masked column mask. Keypad scan result column only masked column mask. Keypad scan result column only masked column mask. Keypad scan result column only masked column mask. Keypad scan result column only masked column mask. Keypad scan result column only masked column mask. Keypad scan result column only masked column mask. Keypad scan result column only masked column mask. Keypad scan result column only masked column mask. Keypad scan result column only masked column mask. Keypad scan result column only masked column mask. Keypad scan result column only masked column mask. Keypad scan result column only masked column mask.
±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller MAX1233/MAX1234
Table Keypad Data Register (Status Register) Descriptions
NAME 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 DESCRIPTION Keypad scan result column masked mask column mask. Keypad scan result column masked mask column mask. Keypad scan result column masked mask column mask. Keypad scan result column masked mask column mask. Keypad scan result column masked mask column mask. Keypad scan result column masked mask column mask. Keypad scan result column masked mask column mask. Keypad scan result column masked mask column mask. Keypad scan result column masked mask column mask. Keypad scan result column masked mask column mask. Keypad scan result column masked mask column mask. Keypad scan result column masked mask column mask. Keypad scan result column masked mask column mask. Keypad scan result column masked mask column mask. Keypad scan result column masked mask column mask. Keypad scan result column masked mask column mask.
Table Keypad Data Register (Pending Register) Descriptions
NAME 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 DESCRIPTION Keypad scan result column only masked column mask. Keypad scan result column only masked column mask. Keypad scan result column only masked column mask. Keypad scan result column only masked column mask. Keypad scan result column only masked column mask. Keypad scan result column only masked column mask. Keypad scan result column only masked column mask. Keypad scan result column only masked column mask. Keypad scan result column only masked column mask. Keypad scan result column only masked column mask. Keypad scan result column only masked column mask. Keypad scan result column only masked column mask. Keypad scan result column only masked column mask. Keypad scan result column only masked column mask. Keypad scan result column only masked column mask. Keypad scan result column only masked column mask.
±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller
Data Register data register stores data that written 8-bit DAC. Table shows configuration data register. right justified with 7-bit storing input data. GPIO Data Register Tables show format descriptions GPIO data register. register left justified with data 15-bit Reading GPIO data register gives state pins. Data written GPIO data register appears those pins, which configured general-purpose outputs. Data written pins configured general-purpose outputs stored.
Applications Information
Programmable 8-/10-/12-Bit Resolution
MAX1233/MAX1234 provide option three different resolutions ADC: bits. Lower resolutions practical some measurements such touch pressure. Lower resolution conversions have smaller conversion times therefore consume less power. Program resolution MAX1233/ MAX1234 12-bit ADCs writing RES1 RES0 bits control register. When MAX1233/ MAX1234 power both bits zero resolution bits with 31µs internally timed reference power-up delay indicated resolution control table. explained control register section, RES1 RES0 bits control reference
MAX1233/MAX1234
Transfer Function
MAX1233/MAX1234 output data straight binary format shown Figure This figure shows ideal output code given input voltage does include effects offset error, gain error, noise, nonlinearity.
OUTPUT CODE
FULL-SCALE TRANSITION
MAX1233 MAX1234
Table Keypad Mapping
COMPONENT
INPUT VOLTAGE (LSB)
VREF 1LSB VREF 4096
3/2LSB
Figure Ideal Input Voltages Output Codes
Table Data Register
BIT15 BIT14 BIT13 BIT12 BIT11 BIT10 BIT9 BIT8 BIT7 BIT6 BIT5 BIT4 BIT3 BIT2 BIT1 BIT0
Table GPIO Data Register
BIT15 GPD7 BIT14 GPD6 BIT13 GPD5 BIT12 GPD4 BIT11 GPD3 BIT10 GPD2 BIT9 GPD1 BIT8 GPD0 BIT7 BIT6 BIT5 BIT4 BIT3 BIT2 BIT1 BIT0
Table GPIO Data Register Descriptions
15.8 NAME GPD7.0 GPIO data bits GPIO pins Reserved DESCRIPTION
±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller MAX1233/MAX1234
+AVDD
FORCE LINE
SENSE LINE
+REF CONVERTER -REF
SENSE LINE
nal, reference, both settle into their final steady-state values before samples inputs, reference voltage continue change during conversion cycle. MAX1233/MAX1234 programmed wait fixed amount time after screen touch been detected before beginning scan. touch-screen settling control bits control register (Table settling delay between zero 100ms. settling problem amplified some applications where external filter capacitors required across touch screen filter noise that generated panel backlight circuitry, etc. values these capacitors cause additional settling time requirement when panel touched. failure settle before conversion start show gain error. Average conversion result writing control register, shown Table minimize noise.
FORCE LINE
Touch-Pressure Measurement
MAX1233/MAX1234 provide methods measurement pressure applied touch screen. Although 8-bit resolution typically sufficient, following calculations 12-bit resolution demonstrating maximum precision MAX1233/MAX1234. Figure shows pressure measurement block diagram. first method performs pressure measurements using known X-plate resistance. After completing three conversions, X-position, Z1-position, position, following equation calculate RTOUCH RTOUCH RXPLATE POSITION 4096
Figure Ratiometric Y-Coordinate Measurement
power-up status when A/D0-A/D3 bits zero. These values initially power-up. (Subsequently A/D0-A/D3 bits zero, other value these bits exclusive resolution programming.)
Differential Ratiometric Touch-Position Measurement
MAX1233/MAX1234 provide differential conversions. Figure shows switching matrix configuration coordinate measurement. +REF -REF inputs connected directly conversion result percentage external resistances, unaffected variation total touch-screen resistance on-resistance internal switching matrix. touch screen remains powered during acquisition conversion process.
second method requires knowing both X-plate Y-plate resistance. Three touch-screen conversions required this method well measurement X-position, Y-position, position touch screen. following equation calculate RTOUCH: 4096 RTOUCH XPLATE POSITION 4096 RYPLATE POSITION 4096
Touch-Screen Settling
There mechanisms that affect voltage level point where touch panel pressed. electrical ringing parasitic capacitance between bottom layers touch screen other mechanical bouncing caused vibration layer touch screen. Thus, input sig-
±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller MAX1233/MAX1234
FORCE LINE SENSE LINE MEASURE X-POSITION
HOST WRITES CONTROL REGISTER
BATTERY INPUT BATTERY INPUT
TOUCH X-POSITION
START CLOCK
XFORCE LINE
YOPEN CIRCUIT
BUSY
MEASURE Z1-RESISTANCE
SENSE LINE
FORCE LINE
REFERENCE AUTO POWER-DOWN MODE? POWER REFERENCE
TOUCH Z1-RESISTANCE
XFORCE LINE
YOPEN CIRCUIT
OPEN CIRCUIT
FORCE LINE
POWER
POWER DOWN
TOUCH Z2-RESISTANCE
CONVERT BATTERY INPUT
POWER DOWN REFERENCE
BUSY HIGH
FORCE LINE XYSENSE LINE MEASURE Z2-RESISTANCE
DATA AVERAGING DONE? TURN CLOCK
Figure Pressure Measurement Block Diagram
DC/DC CONVERTER BATTERY 0.5V 6.0V VBAT 7.5k 2.7V
DONE STORE BATTERY INPUT BAT1 BAT2 REGISTER
AVDD
Figure Battery Voltage-Reading Flowchart
Battery-Voltage Monitors
0.125V 1.5V CONVERTER
2.5k
Figure Battery Measurement Block Diagram
dedicated analog inputs (BAT1 BAT2) allow MAX1233/MAX1234 monitor battery voltages prior DC/DC converter. Figure shows battery voltage monitoring circuitry. MAX1233/ MAX1234 directly monitor battery voltages from 0.5V internal resistor network divides down BAT1 BAT2 that battery voltage results 1.5V input ADC. minimize power consumption, divider only enabled during sampling BAT1 BAT2. Figure illustrates process battery input reading.
±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller MAX1233/MAX1234
Auxiliary Analog Inputs
auxiliary analog inputs (AUX1 AUX2) allow MAX1233/MAX1234 monitor analog input voltages from zero VREF. Figure illustrates process auxiliary input reading.
HOST WRITES CONTROL REGISTER AUXILIARY INPUT AUXILIARY INPUT
Temperature Measurements
MAX1233/MAX1234 provide temperature measurement options: single-ended conversion method differential conversion method. Both temperature measurement techniques rely semiconductor junction's operational characteristics fixed current level. forward diode voltage (VBE) temperature well-defined characteristic. ambient temperature predicted applications knowing value voltage fixed temperature then monitoring delta that voltage temperature changes. Figure illustrates functional block internal temperature sensor. single conversion method requires calibration known temperature, only requires single reading predict ambient temperature. First, internal diode forward bias voltage measured known temperature. Subsequent diode measurements provide estimate ambient temperature through extrapolation. This assumes temperature coefficient -2.1mV/°C. single conversion method results resolution 0.29°C/LSB (2.5V reference) 0.12°C/LSB (1.0V reference) with typical accuracy ±2°C. Figure shows flowchart single temperature measurement. differential conversion method uses measurement points. first measurement performed with fixed bias current into internal diode. second measurement performed with fixed multiple original bias current. voltage difference between first second conversion proportional absolute temperature expressed following formula: (kT/q) ln(N) where: difference diode voltage current ratio second measurement first measurement Boltzmann's constant (1.38 10-23 eV/°Kelvin) electron charge (1.60 10-19 temperature °Kelvin resultant equation solving T(°K) ln(N))
START CLOCK
BUSY
REFERENCE AUTO POWER-DOWN MODE? POWER REFERENCE
POWER
POWER DOWN
CONVERT AUXILIARY INPUT
POWER DOWN REFERENCE
BUSY HIGH DATA AVERAGING DONE? TURN CLOCK
DONE STORE AUXILIARY INPUT AUX1 AUX2 REGISTER
Figure Auxiliary Input Flowchart
CONVERTER
TEMP1
TEMP2
Figure Internal Block Diagram Temperature Sensor
±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller MAX1233/MAX1234
HOST WRITES CONTROL REGISTER TEMPERATURE INPUT HOST WRITES CONTROL REGISTER TEMPERATURE INPUT TEMPERATURE INPUT
START CLOCK
START CLOCK
BUSY
BUSY
CONVERT TEMPERATURE INPUT
REFERENCE AUTO POWER-DOWN MODE? POWER REFERENCE
REFERENCE AUTO POWER-DOWN MODE? POWER REFERENCE
DATA AVERAGING DONE?
STORE TEMPERATURE INPUT TEMP2 REGISTER
POWER
POWER DOWN
POWER
POWER DOWN
CONVERT TEMPERATURE INPUT
POWER DOWN REFERENCE
CONVERT TEMPERATURE INPUT
POWER DOWN REFERENCE
BUSY HIGH DATA AVERAGING DONE? TURN CLOCK DATA AVERAGING DONE?
BUSY HIGH
TURN CLOCK
DONE STORE TEMPERATURE INPUT TEMP1 REGISTER
DONE STORE TEMPERATURE INPUT TEMP1 REGISTER
Figure Single Temperature Measurement Process
Figure Differential Temperature Measurement Process
where: (I1) T(°K) 2.68(°K/mV) V(mV) T(°C) [2.68(°K/mV) V(mV) 273°K]°C/ This differential conversion method does require test temperature calibration provide much improved absolute temperature measurement. differential conversion method, however, resolution
1.6°C/LSB (2.5V reference) 0.65°C/LSB reference) with typical accuracy ±3°C. Figure shows differential temperature measurementprocess. Note: bias current each diode temperature measurement only turned during acquisition and, therefore, does noticeably increase power consumption.
±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller MAX1233/MAX1234
Battery Voltage, Auxiliary Input, Temperature Input Scan
this scan make periodic measurements both battery inputs, both auxiliary inputs, both temperature inputs. respective data registers have latest results each cycle. Thus, single write host MAX1233/MAX1234 control register results different measurements being made. Figure shows this scan operation. keys scanned keypad column pins debounced period time (debounce period) determined bits [DBN2:DBN0] keypad control register. keypad controller continues scanning until keypad stays same state entire debounce period. Keypad Data Keypad data read either keypad data status register (maskable), keypad data pending register (not maskable). keypad mask register used mask individual keys keypad data status register. GPIO Control Write bits [GP7:GP0] GPIO control register configure more R_/C_pins GPIO pin. Write bits [OE7:OE0] GPIO control register configure pins input output. GPIO data read from written GPIO data register. read returns logic state GPIO pin. write sets logic state GPIO output pin. Writing GPIO input effect. GPIO Pullup Disable Register When programmed GPIO output, default, GPIO pins active CMOS outputs. Write pullup disable register configure GPIO output open-drain output.
Touch-Initiated Screen Scans (PENSTS ADSTS
touch-initiated screen-scan mode, MAX1233/MAX1234 automatically perform touchscreen scan upon detecting screen touch. touchscreen scans performed determined [A/D3:A/D0] written control register. Figure shows flowchart complete touch-initiated Xand coordinate scan. Selection resolution, conversion rate, averaging, touch-screen settling time determine overall conversion time. Figure shows complete flowchart touchinitiated scan. Table shows ADSTS Operation.
Host-Initiated Screen Scans (PENSTS ADSTS
this mode, host processor decides when touchscreen scan begins. MAX1233/MAX1234 detect screen touch drive PENIRQ LOW. host recognizes interrupt request choose write control register select touch-screen scan function (PENSTS ADSTS Figures show process host-initiated screen scan. Key-Press Initiated Debounce Scan (KEYSTS1 KEYSTS0 key-press initiated debounce mode, MAX1233/MAX1234 automatically perform debounce upon detecting press. scanning begins once press been detected ends when press been debounced (Figures 9a). Host-Initiated Debounce Scan this mode, host processor decides when debounce scan begins. MAX1233/MAX1234 detect press drive KEYIRQ low. host processor recognizes interrupt request choose write keypad control register initiate debounce scan (Figures 9b). Keypad Debouncing Keys debounced either when press been detected, when commanded host MPU.
Using 8-Bit LCD/TFT Contrast Control
Design Example: 8-bit offers ability control biasing LCD/TFT screens. circuit Figure desired have MAX1677 DC-DC converter's VOUT adjustable. minimum maximum voltages (VDAC(HIGH) DAC(LOW) found Electrical Characteristics table. output voltage MAX1677 (VOUT) calculated noting following equations: VOUT VREFDAC i1R1 [Equation [Equation VREFDAC [Equation (VREFDAC VDAC) [Equation Substituting equations into equation yields: VOUT VREFDAC VREF (VREFDAC VDAC) [Equation
±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller MAX1233/MAX1234
BATTERY VOLTAGE, AUXILIARY INPUT, TEMPERATURE INPUT SCAN ([A/D3:A/D0] 1011)
HOST WRITES CONTROL REGISTER
CONVERT BATTERY INPUT
CONVERT TEMPERATURE INPUT
START CLOCK
BUSY
DATA AVERAGING DONE?
DATA AVERAGING DONE?
REFERENCE AUTO POWER-DOWN MODE? POWER REFERENCE
STORE BATTERY INPUT BAT2 REGISTER
STORE TEMPERATURE INPUT TEMP1 REGISTER
CONVERT AUXILIARY INPUT
CONVERT TEMPERATURE INPUT
POWER
DATA AVERAGING DONE?
DATA AVERAGING DONE?
CONVERT BATTERY INPUT
STORE AUXILIARY INPUT AUX1 REGISTER
STORE TEMPERATURE INPUT TEMP2 REGISTER
DATA AVERAGING DONE?
CONVERT AUXILIARY INPUT
POWER DOWN
POWER DOWN REFERENCE STORE BATTERY INPUT BAT1 REGISTER DATA AVERAGING DONE?
BUSY HIGH
STORE AUXILIARY INPUT AUX2 REGISTER
TURN CLOCK
DONE
Figure Scan Mode Flowchart
±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller MAX1233/MAX1234
PENIRQ-INITIATED SCREEN SCAN SCREEN TOUCH
POWER DOWN
THERE UNREAD SCAN RESULTS? PENIRQ
TURN DRIVERS:
TOUCH-SCREEN SETTLING DONE?
HOST-INITIATED SCAN (FIGURE POWER
PENSTS
CONVERT COORDINATES START CLOCK BUSY TURN DRIVERS: YSTORE COORDINATES REGISTER DATA AVERAGING DONE?
TOUCH-SCREEN SETTLING DONE?
POWER DOWN
BUSY HIGH POWER TURN CLOCK
CONVERT COORDINATES
RESET PENIRQ HIGH
DONE DATA AVERAGING DONE?
STORE COORDINATES REGISTER
Figure Touch-Initiated Coordinate Screen Scan
±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller MAX1233/MAX1234
PENIRQ-INITIATED SCREEN SCAN
SCREEN TOUCH STORE COORDINATES REGISTER CONVERT COORDINATES
THERE UNREAD SCAN RESULTS?
POWER DOWN TURN DRIVERS: XYES STORE COORDINATES REGISTER DATA AVERAGING DONE?
PENIRQ HOST-INITIATED SCAN (FIGURE
TOUCH-SCREEN SETTLING DONE?
PENSTS
CONVERT COORDINATES POWER
START CLOCK CONVERT COORDINATES DATA AVERAGING DONE?
BUSY TURN DRIVERS: DATA AVERAGING DONE?
STORE COORDINATES REGISTER
STORE COORDINATES REGISTER
POWER
TOUCH-SCREEN SETTLING DONE?
BUSY HIGH POWER DOWN
TURN CLOCK POWER TURN DRIVERS: XRESET PENIRQ HIGH CONVERT COORDINATES TOUCH-SCREEN SETTLING DONE?
DONE
DATA AVERAGING DONE?
POWER
Figure Touch-Initiated Coordinate Screen Scan
±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller MAX1233/MAX1234
HOST-INITIATED SCREEN SCAN SCREEN TOUCH
STORE COORDINATES REGISTER
POWER DOWN THERE UNREAD SCAN RESULTS? TURN DRIVERS: PENIRQ TOUCH-SCREEN SETTLING DONE?
PENSTS
TOUCH-INITIATED SCAN (FIGURE
POWER
HOST WRITES CONTROL REGISTER (PENSTS ADSTS
CONVERT COORDINATES
BUSY
DATA AVERAGING DONE?
START CLOCK
STORE COORDINATES REGISTER
TURN DRIVERS: YPOWER DOWN
TOUCH-SCREEN SETTLING DONE?
BUSY HIGH
POWER
TURN CLOCK
RESET PENIRQ HIGH CONVERT COORDINATES DONE
DATA AVERAGING DONE?
Figure Host-Initiated Coordinate Screen Scan
±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller MAX1233/MAX1234
HOST-INITIATED SCREEN SCAN TURN DRIVERS: XSCREEN TOUCH
THERE UNREAD SCAN RESULTS? PENIRQ
TOUCH-SCREEN SETTLING DONE?
TURN DRIVERS:
POWER
TOUCH-SCREEN SETTLING DONE?
CONVERT COORDINATES
PENSTS
TOUCH-INITIATED SCAN (FIGURE
POWER DATA AVERAGING DONE?
HOST WRITES CONTROL REGISTER STORE COORDINATES REGISTER
CONVERT COORDINATES
START CLOCK
DATA AVERAGING DONE?
CONVERT COORDINATES
BUSY STORE COORDINATES REGISTER DATA AVERAGING DONE?
TURN DRIVERS:
POWER DOWN TOUCH-SCREEN SETTLING DONE?
STORE COORDINATES REGISTER
POWER
POWER DOWN
BUSY HIGH CONVERT COORDINATES
TURN CLOCK DATA AVERAGING DONE?
STORE COORDINATES REGISTER
RESET PENIRQ HIGH
DONE POWER DOWN
Figure Host-Initiated Coordinate Screen Scan
±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller MAX1233/MAX1234
HOST-INITIATED DEBOUNCE SCAN KEY-PRESS-INITIATED DEBOUNCE SCAN KEYPAD TOUCH KEYPAD TOUCH
THERE UNREAD DEBOUNCE RESULTS?
THERE UNREAD DEBOUNCE RESULTS?
KEYIRQ
KEYIRQ
KEYSTS1 HOST-INITIATED DEBOUNCE SCAN
KEY-PRESS-INITIATED DEBOUNCE SCAN
KEYSTS1
HOST WRITES CONTROL REGISTER
START CLOCK
START CLOCK BUSY
BUSY SCAN DEBOUNCE KEYS
STORE KEYPAD SCAN RESULTS REGISTER
SCAN DEBOUNCE KEYS
STORE KEYPAD SCAN RESULTS REGISTER BUSY HIGH BUSY HIGH RESET KEYIRQ HIGH RESET KEYIRQ HIGH DONE DONE
Figure Key-Press-Initiated Debounce Scan
Figure Host-Initiated Debounce Scan
±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller MAX1233/MAX1234
VBATT
MAX1233 MAX1234
AVDD
FEEDBACK RESISTORS DACOUT
SIMPLIFIED DC/DC CONVERTER ERROR
VREF 1.25V
CONTROL VOUT (LCD BIAS)
MAX1677
Figure Contrast Control Circuit
MISO MOSI BUSY PENIRQ KEYIRQ DCLK DOUT MISO DCLK DOUT
MAX1233 MAX1234
MICROWIRE MOSI BUSY PENIRQ KEYIRQ
MAX1233 MAX1234
Figure 28a. Interface
Figure 28b. MICROWIRE Interface
Equation shows that maximum output voltage occurs minimum voltage, that minimum output voltage occurs maximum voltage. ensure that desired output swing achieved, choose appropriate values Calculate VOUTMAX using following equation: VOUTMAX VREFMAX (R1MAX R2MIN)VREFMAX (R1MAX R3MIN) (VREFMAX VDACMIN) [Equation OUTMAX exceeds maximum ratings LCD/TFT display, codes that cause output voltage high must avoided.
Calculate VOUTMIN using following equation: VOUTMIN= VREFMIN (R1MIN R2MAX)VREFMIN (R1MAX R3MIN) (VREFMIN VDACMAX) [Equation VOUTMIN desired operation, avoid codes, which cause output voltage low.
Connection Standard Interface
MICROWIRE Interfaces When using interface (Figure 28a) MICROWIRE (Figure 28b), CPOL CPHA least four 8-bit operations necessary read write data to/from MAX1233/MAX1234. DOUT data transitions serial clock's falling edge clocked into DCLK's rising edge. first
±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller MAX1233/MAX1234
MISO QSPI MOSI BUSY PENIRQ KEYIRQ DCLK DOUT
MAX1233 MAX1234
Figure QSPI Interface
connections. Establish single-point analog ground (star ground point) GND. Connect analog grounds star ground. Connect digital system ground star ground this point only. lowest noise operation, ground return star ground's power supply should impedance short possible. High-frequency noise power supply affect high-speed comparator ADC. Bypass supply star ground with 0.1µF capacitor close pins MAX1233/MAX1234 possible. Minimize capacitor lead lengths best supply-noise rejection. power supply very noisy, resistor connected lowpass filter. While using MAX1233/MAX1234 with resistive touch screen, interconnection between converter touch screen should short robust possible. Since resistive touch screens have resistance, longer loose connections source error. Noise also major source error touch-screen applications (e.g., applications that require backlight panel). This noise coupled through panel touch screen cause "flickering" converted data. Utilizing touch screen with bottom-side metal layer connected ground couples majority noise ground. addition, filter capacitors from Xinputs ground also help reduce noise further. Caution should observed settling time touch screen.
SUPPLIES +3V/+5V +3V/+5V
AVDD
DVDD
DGND
MAX1233 MAX1234
*OPTIONAL
DIGITAL CIRCUITRY
Definitions
Integral Nonlinearity
Integral nonlinearity (INL) deviation values actual transfer function from straight line. This straight line either best-straight-line line drawn between points transfer function, once offset gain errors have been nullified. static linearity parameters MAX1233/MAX1234 measured using end-point method.
Figure Power-Supply Grounding Connection
8-bit data streams write command word into MAX1233/MAX1234. next 8-bit data streams contain either input output data. QSPI Interface Using high-speed QSPI interface (Figure with CPOL CPHA MAX1233/MAX1234 support maximum fSCLK 10MHz. DOUT data transitions serial clock's falling edge clocked into DCLK's rising edge.
Differential Nonlinearity
Differential nonlinearity (DNL) difference between actual step width ideal value 1LSB. error specification less than 1LSB guarantees missing codes monotonic transfer function.
Layout, Grounding, Bypassing
best performance, printed circuit boards with good layouts; wire-wrap boards even prototyping. Ensure that digital analog signal lines separated from each other. analog digital (especially clock) lines parallel another, digital lines underneath package. Figure shows recommended system ground
Aperture Jitter
Aperture jitter (tAJ) sample-to-sample variation time between samples.
Aperture Delay
Aperture delay (tAD) time defined between falling edge sampling clock instant when actual sample taken.
±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller
Signal-to-Noise Ratio
waveform perfectly reconstructed from digital samples, signal-to-noise ratio (SNR) ratio full-scale analog input (RMS value) quantization error (residual error). ideal, theoretical minimum analogto-digital noise caused quantization error only results directly from ADC's resolution bits): (6.02 1.76) reality, there other noise sources besides quantization noise: thermal noise, reference noise, clock jitter, etc. computed taking ratio signal noise, which includes spectral components minus fundamental, first five harmonics, offset.
Total Harmonic Distortion
Total harmonic distortion (THD) ratio first five harmonics input signal fundamental itself. This expressed
MAX1233/MAX1234
where fundamental amplitude, through amplitudes 2nd- through 5th-order harmonics, respectively.
Spurious-Free Dynamic Range
Spurious-free dynamic range (SFDR) ratio amplitude fundamental (maximum signal component) value next-largest distortion component.
Signal-to-Noise Plus Distortion
Signal-to-noise plus distortion (SINAD) ratio fundamental input frequency's amplitude equivalent other output signals: SINAD (dB) (SignalRMS NoiseRMS)
Effective Number Bits
Effective number bits (ENOB) indicates global accuracy specific input frequency sampling rate. ideal ADC's error consists quantization noise only. With input range equal full-scale range ADC, calculate effective number bits follows: ENOB (SINAD 1.76) 6.02
Chip Information
TRANSISTOR COUNT: 28,629
±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller MAX1233/MAX1234
Package Information
(The package drawing(s) this data sheet reflect most current specifications. latest package outline information, www.maxim-ic.com/packages.)
.EPS
Maxim cannot assume responsibility circuitry other than circuitry entirely embodied Maxim product. circuit patent licenses implied. Maxim reserves right change circuitry specifications without notice time.
_Maxim Integrated Products, Gabriel Drive, Sunnyvale, 94086 408-737-7600 2002 Maxim Integrated Products Printed registered trademark Maxim Integrated Products.

±15kV ESD-Protected Touch-Screen Controllers Include Keypad Controller

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