ad7879-1acbz-rl Analog Devices, Inc., ad7879-1acbz-rl Datasheet
ad7879-1acbz-rl
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ad7879-1acbz-rl Summary of contents
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... PENIRQ ). The AD7879 offers temperature measure- ment and touch-pressure measurement. The AD7879 is available in a 12-ball, 1.6 mm × WLCSP and in a 16-lead × LFCSP. The part also has either an SPI (AD7879 One Technology Way, P ...
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... Limit Comparison ...................................................................... 17 GPIO ............................................................................................ 17 Register Map ................................................................................... 19 Detailed Register Descriptions ..................................................... 20 Control Registers ............................................................................ 24 Control Register 1 ...................................................................... 24 Control Register 2 ...................................................................... 26 Control Register 3 ...................................................................... 27 Interrupts ..................................................................................... 28 Synchronizing the AD7879 to the Host CPU ......................... 29 Serial Interface ................................................................................ 30 SPI Interface ................................................................................ C-Compatible Interface .......................................................... 32 Grounding and Layout .................................................................. 35 Chip Scale Packages ................................................................... 35 WLCSP Assembly Considerations ........................................... 35 Outline Dimensions ...
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... V 480 650 μA 406 μA 0.5 6 μA Rev Page AD7879 Test Conditions/Comments LSB size = 390 μV LSB size = 390 μV Calibrated at 25°C Uncalibrated accuracy Including 2 μs of acquisition time Digital inputs = ADC on ADC and temperature sensor are off; the reference and oscillator are on ...
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... AD7879 SPI TIMING SPECIFICATIONS (AD7879 −40°C to +85° 1 3.6 V, unless otherwise noted. Sample tested at 25°C to ensure compliance. All input signals are A CC specified with (10 Table 2. 1 Parameter Limit MIN MAX f 5 SCLK ...
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... I C TIMING SPECIFICATIONS (AD7879- −40°C to +85° 1 3.6 V, unless otherwise noted. Sample tested at 25°C to ensure compliance. All input signals are A CC timed from a voltage level of 1.4 V. Table 3. 1 Parameter Limit Unit f 400 kHz max SCLK t 0.6 μs min 1 t 1.3 μs min ...
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... AD7879 ABSOLUTE MAXIMUM RATINGS T = 25°C, unless otherwise specified. 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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... Address Bit 0 for the AD7879-1. This pin can be tied high or low to determine an address for the AD7879-1. SPI Serial Data Input to the AD7879. Address Bit 1 for the AD7879-1. This pin can be tied high or low to determine an address for the AD7879-1. Ground. Ground reference point for all circuitry on the AD7879. All analog input signals and any external reference signal should be referred to this voltage ...
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... AD7879 TYPICAL PERFORMANCE CHARACTERISTICS T = 25° 2 125 kHz SAMPLE 475 470 465 460 455 450 445 440 435 430 425 –40 –25 – TEMPERATURE (°C) Figure 9. Supply Current vs. Temperature 700 600 500 400 300 200 100 0 1.6 1.8 2.0 2.2 2.4 2.6 2.8 V (V) CC Figure 10 ...
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... Figure 18. ADC Code vs. Temperature (Fixed Analog Input) CC Rev Page X– TO GND Y– TO GND –25 – TEMPERATURE (°C) Figure 17 Switch On Resistance vs. Temperature (X+, Y Pin; X−, Y−: Pin to GND TEMPERATURE (°C) AD7879 ...
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... AD7879 1400 1200 1000 800 600 400 200 0 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3.0 3.1 3.2 3.3 3.4 3.5 3.6 V (V) CC Figure 19. Temperature Code vs SNR = 61.58dB THD = 72.34dB –20 –40 –60 –80 –100 –120 –140 –160 FREQUENCY (Hz) Figure 20. Typical FFT Plot for the Auxiliary Channels at 25 kHz Sampling Rate and 1 kHz Input Frequency ...
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... Gain error is the deviation of the last code transition (111 … 110) to (111 … 111) from the ideal (V after the offset error has been adjusted out. On Resistance On resistance is a measure of the ohmic resistance between the drain and the source of the switch drivers. Rev Page AD7879 − 1 LSB) REF ...
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... The high speed SPI serial bus provides control of the devices, as well as communication with the device. The AD7879-1 is available with an I Operating from a single supply from 1 3.6 V, the AD7879 offers a throughput rate of 105 kHz. The device is available in a 1.6 mm × 12-ball wafer level chip scale package (WLCSP) and × ...
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... TEMPERATURE IN+ SENSOR Figure 23. Analog Input Structure The AD7879 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 results registers. When measuring the ancillary analog inputs (AUX, TEMP, or VBAT), the ADC uses a V ...
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... ADC Channel 001b. (Y+ input); POSITION The results are stored in the results registers with Address 0x0D (TEMP). The AD7879 does not provide an explicit output of the temperature reading; the system must perform some external calculations. This method is based on an on-chip diode measurement. ...
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... The ADC output is 983 decimal at 25°C, equivalent to a diode forward voltage of 0.6 V. The ADC output at T ΔT = (880 − 983) × −0.291 = 30° 55°C AMB and T by CAL AMB Rev Page AD7879 −3 = −0.291 is 880. AMB ...
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... LCD screen, noise can be coupled from the screen onto these resistive layers, causing errors in the touch screen posi- tional measurements. The AD7879 contains a filtering block to process the data and discard the spurious noise before sending the information to the host. The goal of this block is not just the suppression of noise ...
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... The ADC channel addresses for AUX is CC 011, and the result is stored in Register 0x0C. BATTERY INPUT The AD7879 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. The voltage to the V ...
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... AD7879 GPIO Interrupt Enable (Bit 12, Control Register 3, Address 0x03) The GPIO pin can operate as an interrupt source to trigger the INT output. This is controlled by Bit 12 in Control Register 3. If the GPIO ALERT interrupt enable = 1, the GPIO can trigger INT . If this bit = 0, the GPIO cannot trigger INT . ...
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... Temperature conversion Measurement 0x0E Revision and device ID Revision and device not write to addresses outside the register map. Rev Page AD7879 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 (AD7879-1) R 0x037A (AD7879) ...
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... AD7879 DETAILED REGISTER DESCRIPTIONS All addresses and default values are expressed in hexadecimal. Table 10. Control Register 1 Data Address Name Bit Description 0x01 Disable PENIRQ 15 Pen interrupt enable PENIRQ pin is enabled PENIRQ is disabled and INT enabled. CHNL ADD[2:0] 14:12 ADC Channel address for manual conversion (mode 01). ...
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... Starts at 128 μs and goes all the way to 4.096 ms in steps of 128 μs. 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 Rev Page AD7879 Default Value 0x4040 ...
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... AD7879 Table 12. Control Register 3 Data Address Name Bit Description 0x03 TEMP MASK 15 TEMP mask bit 0 = temperature measurement is allowed to cause interrupt 1 = temperature measurement is not allowed to cause interrupt AUX/VBAT 14 AUX/VBAT mask bit MASK 0 = AUX/VBAT measurement is allowed to cause interrupt 1 = AUX/VBAT measurement is not allowed to cause interrupt ...
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... Measured Y− input with X− and Y+ excitation (touch-pressure calculation Z2) 0x0C 15:0 AUX/VBAT voltage measurement 0x0D 15:0 Temperature conversion measurement Table 15. Revision/Device ID Register Address Data Bit 0x0E 15:12 11:8 7:0 Description Default Value Unused 0x0379 (AD7879-1) 0x037A (AD7879) Revision and device ID bits Device ID Rev Page AD7879 Default Value 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 ...
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... The ADC then digitizes the selected channels; and the results are written to the result registers. The AD7879 waits for the screen to be touched again, or for a timer event if the screen remains touched, before beginning another sequence of conversions ...
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... Control Register 2 (Bit 9). Ratiometric (differential) conversion is selected by setting the SER/ DFR bit. PENIRQ Enable (Control Register 1, Bit 15) The AD7879 has 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 is working as a pen interrupt and it goes low whenever the screen is touched ...
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... AD7879 15 GPIO PM1 PM0 EN CONTROL REGISTER 2 Control Register 2 (Address 0x02) contains the power management bits, the GPIO settings, the SER/ DFR bit (to choose single or differential methods of touch screen measurement), the averaging and median filter settings, a bit that allows resetting the part, and the first conversion delay bits ...
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... IDLE ADC MODE MASTER MODE SINGLE SLAVE MODE WAIT FOR CONVERSION FIRST TOUCH SEQUENCE CONVERSION SEQUENCE TIMER = 00? NO TOUCHED? START TIMER WAIT FOR TIMER TIMER = 00? START TIMER WAIT FOR TIMER TOUCHED? Figure 32. Conversion Modes AD7879 11 SCREEN NO YES YES NO SCREEN NO YES ...
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... NO EOCS ? Figure 33. Conversion Sequence INTERRUPTS The AD7879 has a dual function interrupt output, INT , as well as a pen down interrupt, PENIRQ . The INT output can be con- figured as a data available interrupt out of limit interrupt GPIO interrupt. INT —Data Available The behavior of the interrupt output is controlled by Bit 13 in Control Register 3 ...
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... When PENIRQ goes low to NOT TOUCHED indicate that the screen has been touched, the host is awakened. The host can then program the AD7879 to convert in any mode and read the results after the conversions are completed. PENIRQ DETECTS ...
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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 on the negative edge of SCL and data is clocked into the device on the positive edge of SCL. SPI Command Word ...
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... Reading Data A read transaction begins when the master writes the command word to the AD7879 with the read/write bit set to 1. The master then supplies 16 clock pulses per data-word to be read, and the AD7879 clocks out data from the addressed register on the SDA line ...
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... The AD7879-1 supports the industry standard 2-wire I interface protocol. The two wires associated with the I the SCL and SDA inputs. The SDA is an I/O pin that allows both register write and register read back operations. The AD7879 always a slave device on the I C serial interface bus ...
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... This allows the master to sequentially write to all registers on the AD7879-1 in the same write transaction. However, the address pointer register does not wrap around after the last address. Any data written to the AD7879-1 after the address pointer has reached its maximum value is discarded. REGISTER ADDRESS[A7:A0] DEV ...
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... REGISTER ADDR S W ADDRESS [7:0] READ (WRITE TRANSACTION SETS UP REGISTER ADDRESS) 6-BIT DEVICE REGISTER ADDR ADDRESS [7:0] OUTPUT FROM MASTER S = START BIT P = STOP BIT OUTPUT FROM AD7879 SR = REPEATED START BIT R = READ BIT REGISTER ADDRESS[A7:A0] DEV DEV DEV DEV R/W ACK ...
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... GROUNDING AND LAYOUT For detailed information on grounding and layout considera- tions for the AD7879, refer to the AN-577 Application Note, Layout and Grounding Recommendations for Touch Screen Digitizers. CHIP SCALE PACKAGES The lands on the chip scale package (CP-16-10) are rectangular. The printed circuit board (PCB) pad for these should be 0.1 mm longer than the package land length, and 0 ...
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... AD7879ACBZ-RL 1 −40°C to +85°C 1 AD7879ACBZ-500R7 −40°C to +85°C AD7879ACPZ-RL 1 −40°C to +85°C 1 AD7879ACPZ-500R7 −40°C to +85°C 1 AD7879-1ACBZ-RL −40°C to +85°C 1 AD7879-1ACBZ-500R7 −40°C to +85°C 1 AD7879-1ACPZ-RL −40°C to +85°C 1 AD7879-1ACPZ-500R7 −40°C to +85°C 1 EVAL-AD7879EBZ ...