1 Features

? 8-channel, 18-bit ADC with analog front-end:

– Dual, simultaneous sampling: 4 × 1 channels

– Constant 1-MΩ input impedance front-end

? Programmable analog input ranges:

– ±12 V, ±10 V, ±7 V, ±5 V, ±3.5 V, and ±2.5 V

– Single-ended and differential inputs

– ±12-V common-mode voltage range

– Input overvoltage protection: Up to ±18 V

? User-selectable analog input bandwidth:

– 21 kHz and 400 kHz

? Integrated low-drift precision references

– ADC reference: 4.096 V

– 2.5-V reference output for external circuits

? Excellent AC and DC performance at fullthroughput:

– DNL: ±0.3 LSB, INL: ±1.5 LSB

– SNR: 92.2 dB, THD: –112 dB

? Power supply:

– Analog and digital: 5 V and 1.8 V

– Digital interface: 1.2 V to 1.8 V

? Temperature range: –40°C to +125°C

2 Applications

? Semiconductor tests

? Battery tests

? Data acquisition (DAQ)

3 Description

The ADS981x is an 8-channel data acquisition (DAQ)

system based on a dual, simultaneous-sampling, 18-

bit successive approximation register (SAR) analogto-

digital converter (ADC). The ADS981x features a

complete analog front-end for each channel with an

input clamp protection circuit, 1-MΩ input impedance,

and a programmable gain amplifier (PGA) with

user-selectable bandwidth options. The high input

impedance allows direct connection with sensors and

transformers, thus eliminating the need for external

driver circuits. The ADS981x can be configured to

accept unipolar or bipolar inputs with up to a ±12-V

common-mode voltage.

The device also features a 4.096-V reference for

the ADC and a 2.5-V reference output for use with

external circuits. A digital interface supporting 1.2-V

to 1.8-V operation enables the ADS981x to be used

without external voltage level translators.