MAX1233_05

19-2512; Rev 3; 8/05 ±15kV ESD-Protected Touch-Screen Controllers Include DAC and Keypad Controller 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. KIT ATION EVALU E AILABL AV 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 Applications Personal Digital Assistants Pagers Touch-Screen Monitors Cellular Phones MP3 Players Portable Instruments Point-of-Sale Terminals Pin Configuration PENIRQ SCLK DOUT BUSY TOP VIEW 28 CS KEYIRQ Ordering Information PART TEMP RANGE -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C PIN-PACKAGE 28 QFN (5mm x 5mm) 28 TQFN (5mm x 5mm) 28 QFN (5mm x 5mm) 28 TQFN (5mm x 5mm) 21 20 19 C4 C3 C2 C1 R1 R2 R3 27 26 DIN 25 24 23 DVDD AVDD *X+ *Y+ *X*YGND 1 2 3 4 5 6 7 10 11 12 13 14 8 9 22 MAX1233EGI MAX1233ETI MAX1234EGI MAX1234ETI MAX1233 MAX1234 18 17 16 15 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. 1 *AUX2 REF *AUX1 QFN/TQFN *PIN INCLUDES 8kV/15kV ESD PROTECTION. ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. DACOUT *BAT1 *BAT2 R4 ±15kV ESD-Protected Touch-Screen Controllers Include DAC and Keypad Controller MAX1233/MAX1234 ABSOLUTE MAXIMUM RATINGS AVDD to GND............................................................-0.3V to +6V DVDD to AVDD .......................................................-0.3V to +0.3V Digital Inputs/Outputs to GND .................-0.3V to (DVDD + 0.3V) X+, Y+, X-, Y-, AUX1, AUX2, and REF to GND ..................................-0.3V to (AVDD + 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 (TA = +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 Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (DVDD = AVDD = +2.7V to +3.6V (MAX1233), DVDD = AVDD = +4.75V to +5.25V (MAX1234), external reference VREF = 2.5V (MAX1233), VREF = 4.096V (MAX1234); fSCLK = 10MHz, fSAMPLE = 50ksps, 12-bit mode, 0.1µF capacitor at REF, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER DC ACCURACY (Note 1) Resolution No Missing Codes Relative Accuracy (Note 2) Differential Nonlinearity Offset Error INL DNL 12-bit mode 10-bit and 8-bit modes 12-bit mode 10-bit and 8-bit modes 12-bit mode 10-bit and 8-bit modes 12-bit mode Gain Error (Note 3) 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 to +3.6V MAX1234 AVDD = DVDD = +5V ±5% TUE 12-bit mode 10-bit and 8-bit modes Software-programmable 8/10/12 bit 11 ±0.8 ±0.5 ±0.8 ±0.5 ±0.5 ±0.5 ±0.5 ±0.5 ±0.5 ±2 ±1 ±0.4 ±0.4 ±0.1 ±0.1 50 ±0.4 mV ±0.3 LSB ppm/°C ppm/°C LSB LSB µVRMS ±4 LSB ±4 ±2 ±2 12 Bits Bits LSB LSB LSB SYMBOL CONDITIONS ANALOG-TO-DIGITAL CONVERTER MIN TYP MAX UNITS Power-Supply Rejection PSR DYNAMIC SPECIFICATIONS (1kHz SINE WAVE, VIN = 2.5VP-P FOR MAX1233, VIN = 4.096VP-P FOR MAX1234, 50ksps, fSCLK = 10MHz) Signal-to-Noise Plus Distortion SINAD 69 dB 2 _______________________________________________________________________________________ ±15kV ESD-Protected Touch-Screen Controllers Include DAC and Keypad Controller ELECTRICAL CHARACTERISTICS (continued) (DVDD = AVDD = +2.7V to +3.6V (MAX1233), DVDD = AVDD = +4.75V to +5.25V (MAX1234), external reference VREF = 2.5V (MAX1233), VREF = 4.096V (MAX1234); fSCLK = 10MHz, fSAMPLE = 50ksps, 12-bit mode, 0.1µF capacitor at REF, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +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 ADC REFERENCE Reference Output Voltage Output Tempco Reference Output Impedance Reference Short-Circuit Current EXTERNAL ADC REFERENCE (INTERNAL REFERENCE DISABLED, REFERENCE APPLIED TO REF) Reference Input Voltage Range Input Impedance Input Current (Note 6) CS = GND or VDD VREF = +2.5V at 50ksps (MAX1233) VREF = +4.096V at 50ksps (MAX1234) Shutdown/between conversions 1.0 1 5 8 ±0.1 10 15 µA VDD V GΩ VREF TCVREF Normal operation 2.5V mode, TA = +25°C 1.0V mode, TA = +25°C 2.470 0.980 2.500 1.000 60 250 18 2.530 1.020 ppm/°C Ω mA V Differential method (Note 4) Single measurement method (Note 5) Differential method (Note 4) Single measurement method (Note 5) -40 1.6 0.3 ±3 ±2 +85 °C °C °C Sampling battery Battery monitor OFF Internal reference -3 0.5 10 1 +3 6.0 V kΩ GΩ % Channel not selected or conversion stopped 0 ±0.1 34 VREF ±1 V µA pF fSCLK 10 30 70 8 30 67dB CONDITIONS MIN TYP -84 84 0.5 50 MAX UNITS dB dB MHz kHz MAX1233/MAX1234 _______________________________________________________________________________________ 3 ±15kV ESD-Protected Touch-Screen Controllers Include DAC and Keypad Controller MAX1233/MAX1234 ELECTRICAL CHARACTERISTICS (continued) (DVDD = AVDD = +2.7V to +3.6V (MAX1233), DVDD = AVDD = +4.75V to +5.25V (MAX1234), external reference VREF = 2.5V (MAX1233), VREF = 4.096V (MAX1234); fSCLK = 10MHz, fSAMPLE = 50ksps, 12-bit mode, 0.1µF capacitor at REF, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER DC 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 DAC OUTPUT Internal DAC Reference Output Load Regulation Output Resistance VREFDAC (Note 10) Code = 255; 0 to 100µA Code = 0; 0 to 100µA Power-down mode TOUCH-SCREEN CONTROLLER On-Resistance Touch-Detection Internal Pullup Resistance Pullup Resistance Pulldown Resistance DIGITAL INPUTS (SCLK, CS, DIN, R_, C_) Input Voltage Low Input Voltage High Input Leakage Current VIL VIH IL 0.7 ✕ DVDD ±0.1 ±1 0.3 ✕ DVDD V V µA Y+, X+ Y-, XX+ to AVDD KEYPAD CONTROLLER C4, C3, C2, C1 (Note 11) R4, R3, R2, R1 (Note 11) DIGITAL INTERFACE 0.5 16 kΩ kΩ 7 9 1 Ω MΩ 0.85 ✕ AVDD 0.9 ✕ AVDD 0.5 0.5 1.0 0.95 ✕ AVDD V LSB MΩ Positive and negative 0.5LSB; 50kΩ and 50pF load (Note 9) Code 127 to 128 From shutdown 0.4 20 40 50 V/µs µs nV/s µs Code = 255, no load Code = 255, no load ±10 INL DNL VOS (Note 7) No missing codes (Note 8) ±1 1 5 SYMBOL CONDITIONS DIGITAL-TO-ANALOG CONVERTER 8 ±1.0 ±1.0 ±25 Bits LSB LSB mV ppm/°C % ppm/°C MIN TYP MAX UNITS 4 _______________________________________________________________________________________ ±15kV ESD-Protected Touch-Screen Controllers Include DAC and Keypad Controller ELECTRICAL CHARACTERISTICS (continued) (DVDD = AVDD = +2.7V to +3.6V (MAX1233), DVDD = AVDD = +4.75V to +5.25V (MAX1234), external reference VREF = 2.5V (MAX1233), VREF = 4.096V (MAX1234); fSCLK = 10MHz, fSAMPLE = 50ksps, 12-bit mode, 0.1µF capacitor at REF, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER Input Capacitance DIGITAL OUTPUT (DOUT) Output Voltage Low Output Voltage High VOL VOH ISINK = 2mA ISINK = 4mA ISOURCE = 1.5mA DVDD 0.5 0.4 DVDD 0.5 2.7 4.75 3 5 0.5 150 150 670 100 40 40 40 0 CLOAD = 50pF CLOAD = 50pF CLOAD = 50pF 40 0 CLOAD = 50pF (Note 13) 40 230 40 45 40 3.6 5.25 5 500 230 900 ns ns ns ns ns ns ns ns ns ns ns ns µA 0.4 0.8 V V SYMBOL CIN CONDITIONS MIN TYP 15 MAX UNITS pF MAX1233/MAX1234 DIGITAL OUTPUT (BUSY, PENIRQ, KEYIRQ, R_, C_) Output Voltage Low Output Voltage High VOL VOH ISINK = 0.2mA ISOURCE = 0.2mA POWER REQUIREMENTS Supply Voltage (Note 12) AVDD / DVDD IAVDD + IDVDD MAX1233 MAX1234 Idle; all blocks shut down Analog and Digital Supply Current TIMING CHARACTERISTICS SCLK Clock Period SCLK Pulse Width High SCLK Pulse Width Low DIN to SCLK Rise Setup SCLK Rise to DIN Hold SCLK Fall to DOUT Valid CS Fall to DOUT Enabled CS Rise to DOUT Disabled CS Fall to SCLK Rise CS Fall to SCLK Ignored SCLK Rise to R_/C_ Data Valid CS Pulse Width High tCP tCH tCL tDS tDH tDOV tDV tDOD tCSS tCSH tGPO tCSW Only ADC on; fSAMPLE = 20ksps Only DAC on; no load Only internal reference on V V V 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 = (VTEMP2 - VTEMP1) × 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 300µVP-P. An external reference below 2.5V can compromise the ADC performance. Note 7: Guaranteed from code 5 to 255. _______________________________________________________________________________________ 5 ±15kV ESD-Protected Touch-Screen Controllers Include DAC and Keypad Controller MAX1233/MAX1234 ELECTRICAL CHARACTERISTICS (continued) (DVDD = AVDD = +2.7V to +3.6V (MAX1233), DVDD = AVDD = +4.75V to +5.25V (MAX1234), external reference VREF = 2.5V (MAX1233), VREF = 4.096V (MAX1234); fSCLK = 10MHz, fSAMPLE = 50ksps, 12-bit mode, 0.1µF capacitor at REF, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) Note 8: Note 9: Note 10: Note 11: Note 12: Note 13: The offset value extrapolated from the range over which the INL is guaranteed. Output settling time is measured by stepping from code 5 to 255, and from code 255 to 5. Actual output voltage at full scale is 255/256 × VREFDAC. Resistance is open when configured as GPIO or in shutdown. AVDD and DVDD should not differ by more than 300mV. When configured as GPIO. Timing Diagram CS tCSW tCSS tCL tCH tCP tCSH tCSH tCSS SCLK tDH tDS DIN tDOV tDV DOUT tDOD R_/C_ NOTE: TIMING NOT TO SCALE. tGPO 6 _______________________________________________________________________________________ ±15kV ESD-Protected Touch-Screen Controllers Include DAC and Keypad Controller MAX1233/MAX1234 Typical Operating Characteristics (AVDD = DVDD = 3V (MAX1233) or 5V (MAX1234), external VREF = +2.5V (MAX1233), external VREF = +4.096V (MAX1234), fSCLK = 10MHz (50% duty cycle), fSAMPLE = 20ksps, CLOAD = 50pF, 0.1µF capacitor at REF, TA = +25°C, unless otherwise noted.) SHUTDOWN CURRENT vs. ANALOG SUPPLY VOLTAGE MAX1233/34 toc01 SHUTDOWN CURRENT vs. TEMPERATURE MAX1233/34 toc02 INTERNAL OSCILLATOR FREQUENCY vs. ANALOG SUPPLY VOLTAGE INTERNAL OSCILLATOR FREQUENCY (MHz) 9.8 9.6 9.4 9.2 9.0 8.8 8.6 8.4 8.2 8.0 2.7 3.2 3.7 MAX1233/MAX1234 MAX1233/34 toc03 300 250 SHUTDOWN CURRENT (nA) 200 150 100 50 0 2.7 3.2 3.7 4.2 4.7 5.2 AVDD (V) 300 250 SHUTDOWN CURRENT (nA) 200 150 100 50 0 -40 -20 0 20 40 60 80 TEMPERATURE (°C) 10.0 4.2 4.7 5.2 AVDD (V) INTERNAL OSCILLATOR FREQUENCY vs. TEMPERATURE MAX1233/34 toc04 TEMP1 DIODE VOLTAGE vs. ANALOG SUPPLY VOLTAGE MAX1233/34 toc05 TEMP1 DIODE VOLTAGE vs. TEMPERATURE 0.75 TEMP1 DIODE VOLTAGE (V) 0.70 0.65 0.60 0.55 0.50 0.45 0.40 MAX1233/34 toc06 9.8 INTERNAL OSCILLATOR FREQUENCY (MHz) 9.6 9.4 9.2 9.0 8.8 8.6 -40 -20 0 20 40 60 80 TEMPERATURE (°C) MAX1233, AVDD = +3.0V MAX1234, AVDD = +5.0V 0.70 0.68 TEMP1 DIODE VOLTAGE (V) 0.66 0.64 0.62 0.60 0.58 0.56 0.54 0.52 0.50 2.7 3.2 3.7 4.2 4.7 0.80 5.2 -40 -25 -10 5 20 35 50 65 80 AVDD (V) TEMPERATURE (°C) TEMP2 DIODE VOLTAGE vs. ANALOG SUPPLY VOLTAGE MAX1233/34 toc07 TEMP2 DIODE VOLTAGE vs. TEMPERATURE MAX1233/34 toc08 0.80 0.90 0.85 TEMP2 DIODE VOLTAGE (V) 0.80 0.75 0.70 0.65 TEMP2 DIODE VOLTAGE (V) 0.75 0.70 0.65 0.60 2.7 3.2 3.7 4.2 4.7 5.2 AVDD (V) 0.60 -40 -25 -10 5 20 35 50 65 80 TEMPERATURE (°C) _______________________________________________________________________________________ 7 ±15kV ESD-Protected Touch-Screen Controllers Include DAC and Keypad Controller MAX1233/MAX1234 Typical Operating Characteristics (continued) (AVDD = DVDD = 3V (MAX1233) or 5V (MAX1234), external VREF = +2.5V (MAX1233), external VREF = +4.096V (MAX1234), fSCLK = 10MHz (50% duty cycle), fSAMPLE = 20ksps, CLOAD = 50pF, 0.1µF capacitor at REF, TA = +25°C, unless otherwise noted.) ADC INTEGRAL NONLINEARITY vs. OUTPUT CODE MAX1233/34 toc09 ADC DIFFERENTIAL NONLINEARITY vs. OUTPUT CODE 0.8 0.6 0.4 DNL (LSB) 0.2 0 -0.2 -0.4 -0.6 -0.8 -1.0 MAX1233/34 toc10 1.0 0.8 0.6 0.4 INL (LSB) 0.2 0 -0.2 -0.4 -0.6 -0.8 -1.0 0 500 1000 1500 2000 2500 3000 3500 4000 OUTPUT CODE 1.0 0 500 1000 1500 2000 2500 3000 3500 4000 OUTPUT CODE ADC OFFSET ERROR vs. ANALOG SUPPLY VOLTAGE MAX1233/34 toc11 ADC OFFSET ERROR vs. TEMPERATURE 1.5 OFFSET ERROR (LSB) 1.0 0.5 0 -0.5 -1.0 -1.5 -2.0 MAX1233/34 toc12 2.0 1.5 OFFSET ERROR (LSB) 1.0 0.5 0 -0.5 -1.0 -1.5 -2.0 2.7 3.2 3.7 4.2 4.7 2.0 5.2 -40 -20 0 20 40 60 80 AVDD (V) TEMPERATURE (°C) ADC GAIN ERROR vs. ANALOG SUPPLY VOLTAGE MAX1233/34 toc13 ADC GAIN ERROR vs. TEMPERATURE 1.5 1.0 GAIN ERROR (LSB) 0.5 0 -0.5 -1.0 -1.5 -2.0 -40 -20 0 20 40 60 80 MAX1233/34 toc14 2.0 1.5 1.0 GAIN ERROR (LSB) 0.5 0 -0.5 -1.0 -1.5 -2.0 2.7 3.2 3.7 4.2 4.7 5.2 AVDD (V) 2.0 TEMPERATURE (°C) 8 _______________________________________________________________________________________ ±15kV ESD-Protected Touch-Screen Controllers Include DAC and Keypad Controller MAX1233/MAX1234 Typical Operating Characteristics (continued) (AVDD = DVDD = 3V (MAX1233) or 5V (MAX1234), external VREF = +2.5V (MAX1233), external VREF = +4.096V (MAX1234), fSCLK = 10MHz (50% duty cycle), fSAMPLE = 20ksps, CLOAD = 50pF, 0.1µF capacitor at REF, TA = +25°C, unless otherwise noted.) ADC EXTERNAL REFERENCE INPUT CURRENT vs. SAMPLING RATE MAX1233 VREF = +2.5V REFERENCE CURRENT (µA) 6 MAX1233/34 toc15 ADC SUPPLY CURRENT vs. SAMPLING RATE MAX1233/34 toc16 8 1000 SUPPLY CURRENT (µA) 100 4 10 2 1 0 100 1k fSAMPLE (Hz) 10k 100k 0.1 1 10 100 1k 10k 100k fSAMPLE (Hz) ADC SUPPLY CURRENT vs. SUPPLY VOLTAGE MAX1233/34 toc17 ADC SUPPLY CURRENT vs. TEMPERATURE AVDD = +3V 120 SUPPLY CURRENT (µA) 100 80 60 40 20 0 MAX1233/34 toc18 250 EXTERNAL REF fSAMPLE = 20ksps 200 SUPPLY CURRENT (µA) 140 150 100 50 0 2.7 3.2 3.7 4.2 4.7 5.2 AVDD (V) -40 -20 0 20 40 60 80 TEMPERATURE (°C) DAC INTEGRAL NONLINEARITY vs. CODE MAX1233/34 toc19 DAC DIFFERENTIAL NONLINEARITY vs. OUTPUT CODE MAX1233/34 toc20 0.075 0.050 0.025 INL (LSB) 0 -0.025 -0.050 -0.075 -0.100 0 50 100 150 CODE 200 250 0.075 0.050 0.025 DNL (LSB) 0 -0.025 -0.500 -0.075 -0.100 300 0 50 100 150 200 250 300 OUTPUT CODE _______________________________________________________________________________________ 9 ±15kV ESD-Protected Touch-Screen Controllers Include DAC and Keypad Controller MAX1233/MAX1234 Typical Operating Characteristics (continued) (AVDD = DVDD = 3V (MAX1233) or 5V (MAX1234), external VREF = +2.5V (MAX1233), external VREF = +4.096V (MAX1234), fSCLK = 10MHz (50% duty cycle), fSAMPLE = 20ksps, CLOAD = 50pF, 0.1µF capacitor at REF, TA = +25°C, unless otherwise noted.) DAC FULL-SCALE ERROR vs. ANALOG SUPPLY VOLTAGE 0.75 0.50 FULL-SCALE ERROR (LSB) 0.25 0 -0.25 -0.50 -0.75 2.5 3.0 3.5 4.0 AVDD (V) 4.5 5.0 MAX1233/34 toc21 DAC FULL-SCALE ERROR vs. TEMPERATURE 1.2 0.8 FULL-SCALE ERROR (LSB) FULL-SCALE ERROR (%) 0.4 0 -0.4 -0.8 -1.2 5.5 0.75 0.50 0.25 0 -0.25 -0.50 -0.75 -40 -20 0 20 40 60 80 TEMPERATURE (°C) MAX1233/34 toc22 1.2 0.8 0.4 0 -0.4 -0.8 -1.2 FULL-SCALE ERROR (%) VREF (V) DAC SUPPLY CURRENT vs. ANALOG SUPPLY VOLTAGE MAX1233/34 toc23 DAC SUPPLY CURRENT vs. TEMPERATURE 175 DAC SUPPLY CURRENT (µA) 150 125 100 75 50 25 MAX1233/34 toc24 250 200 DAC SUPPLY CURRENT (µA) 200 150 100 50 0 2.7 3.2 3.7 4.2 4.7 5.2 AVDD (V) 0 -40 -20 0 20 40 60 80 TEMPERATURE (°C) ADC REFERENCE VOLTAGE vs. ANALOG SUPPLY VOLTAGE 2.550 MAX1233/34 toc25 ADC REFERENCE VOLTAGE vs. TEMPERATURE 1.020 2.60 MAX1233/34 toc26 1.250 2.525 VREF (V) VREF = 1.0V 2.500 VREF = 2.5V 2.475 1.010 VREF (V) VREF (V) 2.55 VREF = 1.0V 1.125 1.000 2.50 1.000 0.990 2.45 VREF = 2.5V 0.875 2.450 2.7 3.2 3.7 4.2 4.7 5.2 AVDD (V) 0.980 2.40 -40 0.750 -20 0 20 40 60 80 TEMPERATURE (°C) 10 ______________________________________________________________________________________ ±15kV ESD-Protected Touch-Screen Controllers Include DAC and Keypad Controller MAX1233/MAX1234 Typical Operating Characteristics (continued) (AVDD = DVDD = 3V (MAX1233) or 5V (MAX1234), external VREF = +2.5V (MAX1233), external VREF = +4.096V (MAX1234), fSCLK = 10MHz (50% duty cycle), fSAMPLE = 20ksps, CLOAD = 50pF, 0.1µF capacitor at REF, TA = +25°C, unless otherwise noted.) ADC REFERENCE SUPPLY CURRENT vs. ANALOG SUPPLY VOLTAGE MAX1233/34 toc27 REFERENCE SUPPLY CURRENT vs. TEMPERATURE MAX1233/34 toc28 750 750 SUPPLY CURRENT (µA) 650 SUPPLY CURRENT (µA) 700 700 650 600 600 550 2.7 3.2 3.7 4.2 4.7 5.2 AVDD (V) 550 -40 -25 -10 5 20 35 50 TEMPERATURE (°C) 65 80 Pin Description PIN 1 2 3* 4* 5* 6* 7 8* 9* 10* 11* NAME DVDD AVDD X+ Y+ XYGND BAT1 BAT2 AUX1 AUX2 FUNCTION Positive Digital Supply Voltage, +2.7V to +3.6V for MAX1233, +4.75V to +5.25V for MAX1234. Bypass with a 0.1µF capacitor. Must be within 300mV of AVDD. 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 DVDD. X+ Position Input Y+ Position Input X- Position Input Y- Position Input Analog and Digital Ground Battery Monitoring Input 1. Measures battery voltages up to 6V. Battery Monitoring Input 2. Measures battery voltages up to 6V. Auxiliary Analog Input 1 to ADC. Measures analog voltages from zero to VREF. Auxiliary Analog Input 2 to ADC. Measures analog voltages from zero to VREF. 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 AVDD. Bypass REF to GND with a 0.1µF capacitor in the external reference mode only. DAC Voltage Output; 0.9 × AVDD Full Scale Keypad Row 4. Can be reconfigured as GPIO3. Keypad Row 3. Can be reconfigured as GPIO2. Keypad Row 2. Can be reconfigured as GPIO1. Keypad Row 1. Can be reconfigured as GPIO0. Keypad Column 1. Can be reconfigured as GPIO4. 12 REF 13 14 15 16 17 18 DACOUT R4 R3 R2 R1 C1 ______________________________________________________________________________________ 11 ±15kV ESD-Protected Touch-Screen Controllers Include DAC and Keypad Controller MAX1233/MAX1234 Pin Description (continued) PIN 19 20 21 22 23 24 25 26 27 28 NAME C2 C3 C4 KEYIRQ PENIRQ DOUT BUSY DIN SCLK CS FUNCTION Keypad Column 2. Can be reconfigured as GPIO5. Keypad Column 3. Can be reconfigured as GPIO6. Keypad Column 4. Can be reconfigured as GPIO7. Active-Low Keypad Interrupt. KEYIRQ is low when a key press is detected. Active-Low Pen Touch Interrupt. PENIRQ is low when a screen touch is detected. Serial Data Output. Data is clocked out at SCLK falling edge. High impedance when CS is high. Active-Low Busy Output. BUSY goes low and stays low during each functional operation. The host controller should wait until BUSY is high again before using the serial interface. Serial Data Input. Data is clocked in on the rising edge of SCLK. Serial Clock Input. Clocks data in and out of the serial interface and sets the conversion speed (duty cycle must be 30% to 70%). Active-Low Chip Select. Data is not clocked into DIN unless CS is low. When CS is high, DOUT is high impedance. *ESD protected: ±8kV Contact, ±15kV Air. 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. 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 (tACQ) is the maximum time the device takes to acquire the input signal to 12bit accuracy. Configure tACQ by writing to the ADC control register. See Table 1 for the maximum input signal source impedance (RSOURCE) 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. 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 AVDD and 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 AVDD and 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 12 ______________________________________________________________________________________ ±15kV ESD-Protected Touch-Screen Controllers Include DAC and Keypad Controller MAX1233/MAX1234 C1 C2 C3 C4 R1 R2 R3 R4 OSCILLATOR KEYPAD CONTROLLER AND GPIO MAX1233 MAX1234 REGISTERS AND SCAN STATE CONTROL TEMP SENSOR *X+ *XX/Y SWITCHES *Y+ *YMUX 12-BIT ADC BATTERY MONITOR BATTERY MONITOR SERIAL DATA I/O DOUT SCLK DIN CS PENIRQ KEYIRQ *BAT1 BUSY *BAT2 *AUX1 *AUX2 REF INTERNAL REFERENCE 2.5V/1.0V 8-BIT DAC DACOUT REF DAC *ESD PROTECTED Figure 1. Block Diagram +AVDD Table 1. Maximum Input Source Impedance ACQUISITION RESOLUTION TIME (µs) (BITS) 1.5 1.5 8 10 12 8 10 12 8 10 12 MAXIMUM RSOURCE FOR COMPLETE SETTLING DURING ACQUISITION (kΩ) 2.6 2.0 1.5 23 19 15 560 470 400 FORCE LINE Y+ SENSE LINE X+ +IN -IN SENSE LINE +REF -REF 1.5 5.0 5.0 5.0 95 95 95 FORCE LINE Y- GND Figure 2. Touch-Screen Measurement ______________________________________________________________________________________ 13 ±15kV ESD-Protected Touch-Screen Controllers Include DAC and Keypad Controller MAX1233/MAX1234 +AVDD VREF TEMP2 TEMP1 MAX1233 MAX1234 X+ XREF ON/OFF Y+ Y+IN +REF CONVERTER -IN 2.5V/1.0V REFERENCE -REF 7.5kΩ VBAT1 7.5kΩ VBAT2 2.5kΩ 2.5kΩ BATTERY ON AUX1 AUX2 GND BATTERY ON Figure 3. Simplified Diagram of Analog Input Section Analog Input Protection Internal protection diodes that clamp the analog input to AVDD and GND allow the analog input pins to swing from GND - 0.3V to AV DD + 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 14 ______________________________________________________________________________________ ±15kV ESD-Protected Touch-Screen Controllers Include DAC and Keypad Controller MAX1233/MAX1234 ment, temperature measurement, or auxiliary input measurement is written to the ADC control register, the device powers on the internal reference, waits for the internal reference to settle, completes the requested scan, and powers down the internal reference. The reference power delay depends upon the ADC resolution selected (see Table 8). Do not bypass REF with an external capacitor when performing scans in auto power-down mode. Full-Power Mode (RES1 = 0, RES0 = 1) In the full-power mode, the RES1 bit is set LOW and RES0 bit is set HIGH. In this mode, the device is powered up and the internal ADC reference is always ON. The MAX1233/MAX1234 internal reference remains fully powered after completing a scan. +1.25V BANDGAP 3R 2x REF PIN OPTIONAL 2R Figure 4. Block Diagram of the Internal Reference measurement of the auxiliary inputs. Figure 4 shows the on-chip reference circuitry of the MAX1233/MAX1234. Set the internal reference voltage by writing to the RFV bits in the ADC control register (see Tables 4, 5, and 12). The MAX1233/MAX1234 can accept an external reference connected to REF for ADC conversion. External Reference The MAX1233/MAX1234 can accept an external reference connected to the REF pin for ADC conversions. The internal reference should be disabled (RES1 = 1) when using an external reference. At a conversion rate of 50ksps, an external reference at REF must deliver up to 15µA of load current and have 50Ω or less output impedance. If the external reference has high output impedance or is noisy, bypass it close to the REF pin with a 0.1µF capacitor. Selecting Internal or External Reference Set the type of reference being used by programming the ADC control register. To select the internal reference, clock zeros into bits [A/D3:A/D0] and a zero to bit RES1, as shown in the Control Registers section. To change to external reference mode, clock zeros into bits [A/D3:A/D0] and a one to bit RES1. See Table 13 for more information about selecting an internal or external reference for the ADC. Internal Clock The MAX1233/MAX1234 operate from an internal oscillator, which is accurate to within 20% of the 10MHz specified clock rate. The internal oscillator controls the timing of the acquisition, conversion, touch-screen settling, reference power-up, and keypad debounce times. 8-Bit DAC The MAX1233/MAX1234 have a voltage-output, true 8-bit monotonic DAC with less than 1LSB integral nonlinearity error and less than 1LSB differential nonlinearity error. It requires a supply current of only 150µA (typ) and provides a buffered voltage output. The DAC is at midscale code at power-up and remains there until a new code is written to the DAC register. During shutdown, the DAC’s output is pulled to ground with a 1MΩ load. The internal DAC can be used in various system applications such as LCD/TFT-bias control, automatic tuning (VCO), power amplifier bias control, programmable threshold levels, and automatic gain control (AGC). The 8-bit DAC in the MAX1233/MAX1234 employs a current-steering topology as shown in Figure 5. At the core of this DAC is a reference voltage-to-current converter (V/I) that generates a reference current. This current is mirrored to 255 equally weighted current sources. DAC switches control the outputs of these current mirrors so that only the desired fraction of the total current-mirror currents is steered to the DAC output. The current is then converted to a voltage across a resistor, and the output amplifier buffers this voltage. DAC Output Voltage The 8-bit DAC code is binary unipolar with 1LSB = (VREF/256). The DAC has a full-scale output voltage of (0.9 × AVDD - 1LSB). Reference Power Modes Auto Power-Down Mode (RES1 = RES0 = 0) The MAX1233/MAX1234 are in auto power-down mode at initial power-up. Set the RES1 and RES0 bits to zero to use the MAX1233/MAX1234 in the auto power-down mode. In this mode, the internal reference is normally off. When a command to perform a battery measure- ______________________________________________________________________________________ 15 ±15kV ESD-Protected Touch-Screen Controllers Include DAC and Keypad Controller MAX1233/MAX1234 +AVDD VREF 1MΩ SW1 SW2 SW255 S1 TOUCH-SCREEN DETECTOR X+ PENIRQ OUT TOUCH SCREEN Y+ Figure 5. DAC Current-Steering Topology Output Buffer The DAC voltage output is an internally buffered unitygain follower that slews at up to ±0.4V/µs. The output can swing from zero to full scale. With a 1/4FS to 3/4FS output transition, the amplifier output typically settles to 1/2LSB in less than 5µs when loaded with 10kΩ in parallel with 50pF. The buffer amplifier is stable with any combination of resistive loads >10kΩ and capacitive loads