The AD7879/AD7889 are 12-bit successive approximation analog-to-digital converters (SAR ADCs) with a synchronous serial interface and low on-resistance switches for driving 4-wire resistive touch screens. The AD7879/AD7889 work with a very low power supply—a single 1.6 V to 3.6 V supply—and feature a throughput rate of 105 kSPS. The devices include a shutdown mode that reduces current consumption to less than 6 μA.
To reduce the effects of noise from LCDs and other sources, the AD7879/AD7889 contain a preprocessing block. The preprocessing function consists of a median filter and an averaging filter. The combination of these two filters provides a more robust solution, discarding the spurious noise in the signal and keeping only the data of interest. The size of both filters is programmable. Other user-programmable conversion controls include variable acquisition time and first conversion delay; up to 16 averages can be taken per conversion. The AD7879/AD7889 can run in slave mode or standalone (master) mode, using an automatic conversion sequencer and timer.
The AD7879/AD7889 have a programmable pin that can operate as an auxiliary input to the ADCs, as a battery monitor, or as a general-purpose input/output (GPIO). In addition, a programmable interrupt output can operate in three modes: as a general-purpose interrupt to signal when new data is available (DAV), as an interrupt to indicate when limits are exceeded (INT), or as a pen-down interrupt when the screen is touched (PENIRQ). The AD7879/AD7889 offer temperature measurement and touch pressure measurement.
The AD7879 is available in a 12-ball, 1.6 mm × 2 mm WLCSP and in a 16-lead, 4 mm × 4 mm LFCSP. The AD7889 is available in a backside coated version of the WLCSP. Both devices support an SPI interface (AD7879/AD7889) or an I2C interface (AD7879-1/ AD7889-1).
Features and Benefits | Analog to Digital ConvertersBuilding Technology
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| Document | note |
| AD7879/AD7889: Low Voltage Controller for Touch Screens Data Sheet (Rev. D) | PDF 772.06 K |
| Part Number | Package | Packing Qty | Temp Range | Price 100-499 | Price 1000+ | RoHS |
|---|---|---|---|---|---|---|
| AD7889-1ACBZ-500R7 Obsolete | 12 ball WLCSP (1.5x2.01) | OTH 500 | -40 to 85C | 0 | 0 | Y |
| AD7889-1ACBZ-RL Obsolete | 12 ball WLCSP (1.5x2.01) | REEL 10000 | -40 to 85C | 0 | 0 | Y |
| AD7889-1ACBZ-RL7 Obsolete | 12 ball WLCSP (1.5x2.01) | REEL 3000 | -40 to 85C | 0 | 0 | Y |
| AD7889ACBZ-500R7 Obsolete | 12 ball WLCSP (1.5x2.01) | OTH 500 | -40 to 85C | 0 | 0 | Y |
| AD7889ACBZ-RL Last Time Buy | 12 ball WLCSP (1.5x2.01) | REEL 10000 | -40 to 85C | 0 | 0 | Y |
