Hi team,
My customer was using ADS8866 and they are interested in higher grade ADS8867. Just want to know is ADS8867 pin-to-pin compatible to ADS8866? Do they need to modify the circuit to use ADS8867?
Thanks a lot.
Best Regards,
Wei-Hao
Hi Wei-Hao,
The ADS8866 is a single-ended input device, while the ADS8867 is a fully-differential input version. They require different input driving circuits in the analog front-end but are pin compatible from the digital interface, reference voltage and voltage supply perspective.
The ADS8866 with single-ended inputs converts the analog input voltage with respect to ground (GND); where AINM (negative input) is typically connected to analog ground where the voltage in the negative input is fixed.
A fully-differential such as the ADS8867 converts the differential voltage across its inputs (AINP-AINM) where both the positive input (AINP) and negative input (AINM) accept a dynamically changing signal; where the positive and negative input signals are complementary or inverted from each other. A device with fully differential inputs as the ADS8867 is typically driven using a fully-differential amplifier (FDA) such as the THS4521, THS4531, THS4551 or with a operational amplifiers driving each input (one OPA driving AINP, another amplifier driving AINM).
Please refer to the TI Precision Labs-ADCs Training Sessions and figures below.
https://training.ti.com/ti-precision-labs-adcs-sar-adc-input-types
Driving the Fully-Differential SAR ADC Training Sessions:
https://training.ti.com/ti-precision-labs-adcs-driving-a-sar-adc-with-a-fully-differential-amplifier
Thank you and Kind Regards,
Luis Chioye
Precision ADC Applications
Single-Ended VS Fully-Differential Input
Fully-Differential Input SAR ADC
