AD7889 Analog Devices, AD7889 Datasheet
AD7889
Specifications of AD7889
Related parts for AD7889
AD7889 Summary of contents
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... PENIRQ ). The AD7879/AD7889 offer temp- erature measurement and touch-pressure measurement. The AD7879 is available in a 12-ball, 1.6 mm × WLCSP and in a 16-lead × LFCSP. The AD7889 is available in a backside-coated version of the WLCSP. Both parts support an SPI interface (AD7879/AD7889 (AD7879-1/AD7889-1) ...
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... Conversion Timing ........................................................................ 20 Register Map ................................................................................... 21 Detailed Register Descriptions ..................................................... 22 Control Registers ............................................................................ 26 Control Register 1 ...................................................................... 26 Control Register 2 ...................................................................... 28 Control Register 3 ...................................................................... 29 Interrupts ..................................................................................... 30 Synchronizing the AD7879/AD7889 to the Host CPU ........ 31 Serial Interface ................................................................................ 32 SPI Interface ................................................................................ 32 I C-Compatible Interface .......................................................... 34 2 Grounding and Layout .................................................................. 37 Lead Frame Chip Scale Packages ............................................. 37 WLCSP Assembly Considerations ...
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... V CC 0.4 V ±0.1 µ 9.5 µs 105 kSPS Rev Page AD7879/AD7889 Test Conditions/Comments LSB size = 390 µV. LSB size = 390 µV. Calibrated at 25°C. Uncalibrated accuracy Including 2 µs of acquisition time, MAV filter off. 2 µs of additional time is required if MAV filter is on. ...
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... See the Terminology section. 2 Guaranteed by characterization; not production tested. 3 Sample tested at 25°C to ensure compliance. SPI TIMING SPECIFICATIONS (AD7879/AD7889 1 3 −40°C to +85°C, unless otherwise noted. Sample tested at 25°C to ensure compliance. All input signals are CC A specified with t ...
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... TIMING SPECIFICATIONS (AD7879-1/AD7889 −40°C to +85°C, unless otherwise noted. Sample tested at 25°C to ensure compliance. All input signals are CC A timed from a voltage level of 1.4 V. Table 3. Parameter 1 Limit f 400 SCL 100 4 t 300 ...
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... AD7879/AD7889 ABSOLUTE MAXIMUM RATINGS T = 25°C, unless otherwise noted. A Table 4. Parameter V to GND CC Analog Input Voltage to GND AUX/VBAT to GND Digital Input Voltage to GND Digital Output Voltage to GND Input Current to Any Pin Except Supplies ESD Rating (X+, Y+, X−, Y−) Air Discharge Human Body Model ...
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... Power Supply Input and ADC Reference. Chip Select for the SPI Serial Interface on the AD7879/AD7889. Active low Address Bit 0 for the AD7879-1/AD7889-1. This pin can be tied high or low to determine an address for the AD7879-1/AD7889-1 (see Table 25). SPI Serial Data Input to the AD7879/AD7889 Address Bit 1 for the AD7879-1/AD7889-1 ...
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... AD7879/AD7889 PIN INDICATOR 12 PENIRQ/INT/DAV AD7879 TOP VIEW (Not to Scale) X– DOUT NOTES CONNECT 2. THE EXPOSED PAD IS NOT CONNECTED INTERNALLY. FOR INCREASED RELIABILITY OF THE SOLDER JOINTS AND MAXIMUM THERMAL CAPABILITY RECOMMENDED THAT THE PAD BE SOLDERED TO THE GROUND PLANE. ...
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... TEMPERATURE (°C) Figure 11. Full Power-Down I vs. Temperature 3.0 3.2 3.4 3.6 CC 2.0 1.5 1.0 0.5 –0.5 –1.0 –1.5 –2 100 Rev Page AD7879/AD7889 1.0 0.8 0.6 0.4 0.2 2.6V 0 3.6V –0.2 –0.4 1.6V –0.6 –0.8 –1.0 –40 –25 – TEMPERATURE (°C) Figure 12. Change in ADC Gain vs. Temperature 1.0 0.8 0.6 0.4 1.6V 0.2 0 –0.2 3.6V – ...
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... AD7879/AD7889 1.0 0.8 0.6 0.4 0.2 0 –0.2 –0.4 –0.6 –0.8 –1.0 1 501 1001 1501 2001 2501 CODE Figure 15. ADC DNL 1.6 1.8 2.0 2.2 2.4 2.6 2.8 V (V) CC Figure 16. Switch On Resistance vs. V (X+, Y+: Pin X−, Y−: Pin to GND) CC 3001 3501 4001 X– TO GND Y– TO GND 3 ...
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... Figure 20. Typical FFT Plot for the Auxiliary Channels at 25 kHz Sampling Rate and 1 kHz Input Frequency 250 200 150 100 for 25°C Figure 21. Typical Uncalibrated Accuracy for the Battery Channel (25°C) CC Rev Page AD7879/AD7889 MEAN: –1.98893 SD: 0.475534 50 0 –4 –3 –2 –1 ERROR (%) ...
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... AD7879/AD7889 TERMINOLOGY Differential Nonlinearity (DNL) DNL is the difference between the measured and the ideal 1 LSB change between any two adjacent codes in the ADC. Integral Nonlinearity (INL) INL is the maximum deviation from a straight line passing through the endpoints of the ADC transfer function. The ...
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... C interface. Operating from a single supply from 1 3.6 V, the AD7879/ AD7889 offer a throughput rate of 105 kHz. The device is avail- able in a 1.6 mm × 2 mm, 12-ball wafer level chip scale package (WLCSP) and × 4 mm, 16-lead lead frame chip scale package (LFCSP). ...
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... TEMPERATURE IN+ SENSOR Figure 23. Analog Input Structure The AD7879/AD7889 can be set up to automatically convert either specific input channels or a sequence of channels. The results of the ADC conversions are stored in the result registers. When measuring the ancillary analog inputs (AUX, TEMP, or VBAT), the ADC uses a V ...
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... TOUCH-PRESSURE MEASUREMENT The pressure applied to the touch screen by a pen or finger can also be measured with the AD7879/AD7889 using some simple calculations. The contact resistance between the X and Y plates is measured, providing a good indication of the size of the depressed area and, therefore, the applied pressure. The area of the spot that is touched is proportional to the size of the object touching it ...
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... AD7879/AD7889 Temperature Calculations If an explicit temperature reading in degrees Celsius is required, calculate for the single-measurement method as follows: 1. Calculate the scale factor of the ADC in degrees per LSB. Degrees per LSB = ADC LSB size/−2 /4096)/−2 Save the ADC output the calibration temperature, ...
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... LCD screen, noise can be coupled from the screen onto these resistive layers, causing errors in the touch screen positional measurements. The AD7879/AD7889 contain a filtering block to process the data and discard the spurious noise before sending the infor- mation to the host. The purpose of this block is not only the suppression of noise ...
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... Control Register 1, Address 0x01), and the result is stored in the AUX/VBAT result register (Address 0x0C). BATTERY INPUT The AD7879/AD7889 can monitor battery voltages from 0 when the BAT measurement is selected. Figure 28 shows a block diagram of a battery voltage monitored through the VBAT pin ...
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... INT is asserted if the GPIO data register bit is set when the GPIO is configured as an input, provided that INT is enabled. INT is triggered only when the GPIO is configured as an input, that is, when GPIO DIR = 1. INT is cleared only when the GPIO signal or the GPIO enable bit changes. Rev Page AD7879/AD7889 ...
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... AD7879/AD7889 CONVERSION TIMING Conversion timing or update rate is the rate at which the AD7879 provides converted values from the ADC so that the XY positions in the touch screen can be updated. In other words, the update rate is the timing required to give valid measurements in the sequencer. Figure 29 shows conversion timing for a conversion sequence. ...
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... X+ measurement for touch-pressure calculation (Z1) Y− measurement for touch-pressure calculation (Z2) AUX/VBAT voltage measurement Temperature conversion measurement Revision and device ID Rev Page AD7879/AD7889 Default Value Type 0x0000 R/W 0x0000 R/W 0x4040 R/W 0x0000 R/W 0x0000 R/W 0x0000 R/W 0x0000 R/W 0x0000 R/W 0x0000 R 0x0000 R 0x0000 R 0x0000 R 0x0000 R 0x0000 R 0x0379 R (AD7879-1/AD7889-1) 0x037A R (AD7879/AD7889) ...
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... AD7879/AD7889 DETAILED REGISTER DESCRIPTIONS All addresses and default values are expressed in hexadecimal. Table 12. Control Register 1 Address Bit Name Data Bit 0x01 Disable PENIRQ 15 CHNL ADD[2:0] [14:12] ADC MODE[1:0] [11:10] ACQ[1:0] [9:8] TMR[7:0] [7: GPIO is enabled in Control Register 2 (Bit 13), AUX and VBAT are both ignored. If AUX and VBAT are both selected in Control Register 3 and GPIO is disabled, AUX is ignored and VBAT is measured ...
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... Starts at 128 µs (default) and continues to 4.096 ms in steps of 128 µs (see Table 22). 1 This delay occurs before conversion of the X and Y coordinate channels (including Z1 and Z2) to allow for screen settling and before the first conversion to allow the ADC to power up. 1 Rev Page AD7879/AD7889 Default Value 0x4040 ...
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... AD7879/AD7889 Table 14. Control Register 3 Address Bit Name Data Bit 0x03 TEMP MASK 15 AUX/VBAT MASK 14 INT MODE 13 GPIO ALERT 12 AUX/VBAT LOW 11 AUX/VBAT HIGH 10 TEMP LOW 9 TEMP HIGH AUX 3 VBAT 2 TEMP 1 Not used 0 If GPIO is enabled in Control Register 2 (Bit 13), AUX and VBAT are both ignored. If AUX and VBAT are both selected and GPIO is disabled, AUX is ignored and VBAT is 1 measured ...
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... Measured Y − input with X− and Y+ excitation (touch-pressure calculation Z2) AUX/VBAT voltage measurement Temperature conversion measurement Description Unused Revision and device ID bits Device ID Rev Page AD7879/AD7889 Default Value 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 Default Value 0x0379 (AD7879-1/AD7889-1) 0x037A (AD7879/AD7889) ...
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... The ADC then digitizes the selected channels, and the results are written to the result registers. Before beginning another sequence of conversions, the AD7879/AD7889 wait for the screen to be touched again or for a timer event if the screen remains touched. ...
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... Control Register 2 (Bit 9). Ratiometric (differential) conversion is selected by clearing the SER/ DFR bit. PENIRQ Enable (Control Register 1, Bit 15) The AD7879/AD7889 have a dual function output that performs as PENIRQ or INT depending on the pen interrupt enable bit (Bit 15 of Control Register 1). When this bit is set to 0, the pin functions as a pen interrupt and goes low whenever the screen is touched ...
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... AD7879/AD7889 15 GPIO PM1 PM0 EN CONTROL REGISTER 2 Control Register 2 (Address 0x02) contains the ADC power management bits, the GPIO settings, the SER/ DFR bit (to choose the single-ended or differential method of touch screen measurement), the averaging and median filter settings, a bit that allows resetting of the part, and the first conversion delay bits ...
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... WAIT FOR FIRST TOUCH CONVERSION SEQUENCE NO SCREEN TOUCHED? YES YES TIMER = 00? NO START TIMER WAIT FOR TIMER SCREEN NO TOUCHED? YES Rev Page AD7879/AD7889 0 NOT Z1 Z2 AUX VBAT TEMP USED START OF CONVERSION SET CHANNEL SEQUENCE YES FCD REQ’D? NO FCD WAIT FOR ...
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... The behavior of the interrupt output is controlled by Bit 13 in Control Register 3. In default mode (Bit 13 = 0), INT operates as a data available interrupt ( DAV ). When the AD7879/AD7889 finish a conversion or a conversion sequence, the interrupt is asserted to let the host know that new ADC data is available in the result registers ...
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... When PENIRQ goes low to indicate that the screen has been touched, the host is awakened. The host can then program the AD7879/AD7889 to convert in any mode and read the results after the conversions are completed. In master mode, INT or DAV can also be used as an interrupt to the host ...
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... A chip select pin ( CS ) enables or disables the serial interface required for correct operation of the SPI interface. Data is clocked out of the AD7879/AD7889 on the falling edge of SCL, and data is clocked into the device on the rising edge of SCL. SPI Command Word ...
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... CW[9:0] = [AD9, AD8, AD7, AD6, AD5, AD4, AD3, AD2, AD1, AD0] (10-BIT MSB JUSTIFIED REGISTER ADDRESS) Reading Data A read transaction begins when the master writes the command word to the AD7879/AD7889 with the read/write bit set to 1. The master then supplies 16 clock pulses per data-word to be read, and the AD7879/AD7889 clock out data from the addressed register on the DOUT line ...
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... When all data bytes are read or written, a stop condition is established. A stop condition is defined by a low-to-high transition on SDA while SCL remains high. If the AD7879-1/ AD7889-1 encounter a stop condition, they return to the idle condition. Rev Page ...
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... Writing Data over the Bus The process of writing to the AD7879-1/AD7889-1 over the I bus is shown in Figure 43 and Figure 45. The device address is sent over the bus followed by the R/ W bit set to 0. This is followed by one byte of data that contains the 8-bit address of the internal data register to be written ...
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... REGISTER DATA[D7:D0] DEVICE ADDRESS DEV DEV D7 D6 ACK R AD7879-1/AD7889-1 REGISTER DATA[D7:D0] DEVICE ADDRESS DEV DEV DEV D7 D6 ACK R Timing for Single Register Readback Operation ...
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... GROUNDING AND LAYOUT For detailed information on grounding and layout considerations for the AD7879/AD7889, refer to the AN-577 Application Note, Layout and Grounding Recommendations for Touch Screen Digitizers. LEAD FRAME CHIP SCALE PACKAGES The lands on the lead frame chip scale package (CP-16-10) are rectangular. The printed circuit board (PCB) pad for these lands should be 0 ...
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... AD7879/AD7889 OUTLINE DIMENSIONS 1.67 1.61 1.55 BALL 1 IDENTIFIER TOP VIEW (BALL SIDE DOWN) 1.555 1.505 1.455 BALL 1 IDENTIFIER TOP VIEW (BALL SIDE DOWN) Figure 48. 12-Ball, Backside-Coated Wafer Level Chip Scale Package [WLCSP] PIN 1 INDICATOR 12° MAX 1.00 0.85 0.80 SEATING PLANE 0.65 0.59 0.53 SEATING PLANE 2.07 0.36 2.01 0.32 1.95 0.28 0.10 MAX 0.37 COPLANARITY 0.35 0.28 0.33 0.24 0.20 Figure 47. 12-Ball Wafer Level Chip Scale Package [WLCSP] ...
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... AD7889ACBZ-RL −40°C to +85°C AD7889ACBZ-500R7 −40°C to +85°C AD7889-1ACBZ-RL −40°C to +85°C AD7889-1ACBZ-RL7 −40°C to +85°C AD7889-1ACBZ-500R7 −40°C to +85°C EVAL-AD7879EBZ EVAL-AD7879-1EBZ RoHS Compliant Part. Serial Interface Description Package Description SPI Interface ...
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... AD7879/AD7889 NOTES I C refers to a communications protocol originally developed by Philips Semiconductors (now NXP Semiconductors). 2 ©2008–2010 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D07667-0-11/10(C) Rev Page ...