1 Features

• 16-Bit ADCs with Integrated Analog Front-End

• 4-, 8-Channel MUX with Auto and Manual Scan

• Channel-Independent Programmable Inputs:

– ±12.288V, ±6.144V, and ±3.072V

– 12.288V to 0V and 6.144V to 0V

• 5V Analog Supply: 1.65V to 5V I/O Supply

• Constant Resistive Input Impedance: 1.2MΩ

• Input Overvoltage Protection: Up to ±20V

• On-Chip, 4.096V Reference with Low Drift

• Excellent Performance:

– 500kSPS Aggregate Throughput

– DNL: ±0.6LSB; INL: ±0.8LSB

– Low Drift for Gain Error and Offset

– SNR: 91.5dB; THD: –102dB

– Low Power: 65mW

• AUX Input → Direct Connection to ADC Inputs

• ALARM → High and Low Thresholds per Channel

• SPI™-Compatible Interface with Daisy-Chain

• Industrial Temperature Range: –40°C to 125°C

2 Applications

• Analog input modules

• AC transmission relays

3 Description

The ADS8684W and ADS8688W are 4-channel and

8-channel, integrated data acquisition systems based

on a 16-bit successive approximation (SAR) analogto-

digital converter (ADC), operating at a throughput

of 500kSPS. The devices feature integrated analog

front-end circuitry for each input channel with

overvoltage protection up to ±20V, a 4-channel or

8-channel multiplexer with automatic and manual

scanning modes, and an on-chip, 4.096V reference

with low temperature drift. Operating on a single 5V

analog supply, each input channel on the devices

can independently support bipolar input ranges of

±12.288V, ±6.144V, and ±3.072V and unipolar input

ranges of 12.288V to 0V and 6.144V to 0V.

The ADS8684W and ADS8688W offer a simple SPIcompatible

serial interface to the digital host and also

support daisy-chaining of multiple devices. The digital

supply operates from 1.65V to 5.25V, enabling direct

interface to a wide range of host controllers.