AD7877ACPZ-REEL7

触摸屏控制器 Touch Screen Controller

Product Details

The AD7877 is a 12-bit, successive approximation ADC with a synchronous serial interface and low on resistance switches for driving touch screens. The AD7877 operates from a single 2.7 V to 5.25 V power supply functional operation to 2.2 V, and features throughput rates of 125 kSPS. The AD7877 features direct battery measurement on two inputs, temperature and touch-pressure measurement.

The AD7877 also has an on-board reference of 2.5 V. When not in use, it can be shut down to conserve power. An external reference can also be applied and varied from 1 V to +VCC, with an analog input range of 0 V to VREF. The device includes a shutdown mode that reduces its current consumption to less than 1 μA.

To reduce the effects of noise from LCDs, the acquisition phase of the on-board ADC is controlled via the STOPACQ pin. User-programmable conversion controls include variable acquisition time and first conversion delay. Up to 16 averages can be taken per conversion. There is also an on-board DAC for LCD back-light or contrast control. The AD7877 runs in either slave or master mode using a conversion sequencer and timer. It is ideal for battery-powered systems such as personal digital assistants with resistive touch screens and other portable equipment.

The part is available in a 32-lead lead frame chip scale package LFCSP, and a 25-ball wafer level chip scale package WLCSP. AD7877W model is qualified for automotive applications.

**Applications**

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Personal digital assistants

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Smart hand-held devices

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Touch screen monitors

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Point-of-sale terminals

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Medical devices

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Cell phones

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Pagers

### Features and Benefits

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4-wire touch screen interface

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LCD noise reduction feature STOPACQ pin

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Automatic conversion sequencer and timer

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User-programmable conversion parameters

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On-chip temperature sensor:

−40°C to +85°C

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On-chip 2.5 V reference

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On-chip 8-bit DAC

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3 auxiliary analog inputs

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1 dedicated and 3 optional GPIOs

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3 interrupt outputs

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2 direct battery measurement channels 0.5 V to 5 V

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Qualified for automotive applications

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See Data Sheet for additional features