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Introduction

The AD7877WACPZ is a 12-bit successive approach ADC with a synchronous serial interface and a low-on-resistance switch to drive the touch screen, powered from a single supply of 2.7V to 5.25V (2.2V also works) and a throughput rate of 125 kSPS. The AD7877WACPZ can be used for battery measurement, temperature measurement and touch pressure measurement on both inputs.

The AD7877WACPZ also has a 2.5V on-chip reference voltage source. When not in use, the reference voltage source can be turned off to reduce power consumption. External reference voltages can also be used and vary from 1 V to +VCC, with analog inputs ranging from 0 V to VREF. The AD7877WACPZ device has a relevant off mode that consumes less than 1 µA.

The phase acquisition of the on-chip ADC is controlled by the STOPACQ pin, which reduces the noise effect from the LCD. User programmable conversion control includes variable acquisition time and first conversion delay. Up to 16 means can be used per transformation. The device also has an on-chip DAC to control the LCD backlight or contrast. The AD7877WACPZ uses a conversion sequencer and timer to operate in slave or master mode, making it ideal for battery-powered systems such as personal digital assistants with resistive touch screens and other portable devices.

AD7877WACPZ block diagram

Application field

The AD7877WACPZ is used in a wide range of devices requiring high precision touch screen control, including:

Personal digital assistant

Smart handheld devices

Touch screen monitor

POS terminal

Medical equipment

Cellular telephone

pager

Key features of AD7877WACPZ include:

4-wire touch screen interface

LCD noise reduction feature (STOPACQ pin)

Automatic conversion sequencer and timer

User programmable conversion parameters

On-chip temperature sensor: -40°C to +85°C

2.5V internal reference voltage source

On chip 8-bit DAC

3 auxiliary analog inputs

1 dedicated GPIO and 3 optional GPIO

3 interrupt output

2 battery measurement channels (0.5V to 5V)

Certified for automotive applications

Basic parameter

Product Number: AD7877WACPZ

Touch screen: 4-wire resistive

Resolution (bit) : 12 b

Interface: SPI

Voltage reference: external, internal

Voltage - Power supply: 2.7V ~ 5.25V

Current - Power supply: 1 µA

Operating temperature: -40°C ~ 85°C

Mounting type: Surface mount type

Class: Automobile class

Device package: 32-LFCSP-VQ (5x5)

If you need to purchase an ADI [AD7877WACPZ Touch Screen Controller], you can contact Mingada Electronics by visiting the website (www.hkmjd.com).