1 Features

• 16-bit ADC with integrated analog front-end

• High speed:

– ADS8681W: 1MSPS

– ADS8685W: 500kSPS

– ADS8689W: 100kSPS

• Software programmable input ranges:

– Bipolar differential ranges: ±12.288V, ±10.24V,

±6.144V, ±5.12V, and ±2.56V

– Unipolar differential ranges: 0V–12.288V,

0V–10.24V, 0V–6.144V, and 0V–5.12V

• Analog supply (5V): 1.65V to 5V I/O supply

• Constant resistive input impedance ≥ 1MΩ

• Input bandwidth: 450kHz

• Input overvoltage protection: Up to ±20V

• On-chip, 4.096V reference with low drift

• Excellent performance:

– DNL: ±0.6LSB; INL: ±0.6LSB

– SNR: 80dB; THD: –105dB

• ALARM feature with high, low threshold

• multiSPI™ interface with daisy-chain

• Temperature range: –40°C to +125°C

2 Applications

• Analog input modules

• Semiconductor tests

• Servo drive control modules

3 Description

The ADS8681W, ADS8685W, and ADS8689W are an

integrated data acquisition system family based on

a successive approximation (SAR) analog-to-digital

converter (ADC) topology. The devices feature a

high-speed, high-precision SAR ADC, integrated

differential analog front-end (AFE) input driver circuit.

The ADS868xW includes an overvoltage protection

circuit up to ±20V and an on-chip 4.096V reference

with extremely low temperature drift.

The devices operate on a single 5V analog supply,

but support true bipolar input ranges and unipolar

input ranges. The bipolar input ranges are ±12.288V,

±6.144V, ±10.24V, ±5.12V, and ±2.56V, and the

unipolar input ranges are from 0V to 12.288V, 10.24V,

6.144V, and 5.12V. The devices offer a high resistive

input impedance (≥ 1MΩ) irrespective of the selected

input range.

The multiSPI digital interface is backward-compatible

to the traditional SPI protocol. Additionally,

configurable features simplify interface to a wide

range of host controllers.