Hello Precision ADC Support Team,
My customer a precision temperature measuring device using ad7124-4, the analog schematic is attached as well as code and registers values. In case of connected RTD they provide 2 measurements – first with source current through RTD and second with sink current through RTD. They switch a current direction using a multiplexor.
They have an issue:
They measure a temperature of ad7124 using an internal temp sensor after each measurement. In case of forwarding AIN0 and AIN1 polarity (source current) when they measure internal temperature, everything is ok. In case of sink current, the temperature reading (ADC code) grows 3 times. It is very strange because when temperature measurement occurs, AIN0 and AIN1 are switched off. Also, they noticed that temperature reading grows when the voltage on AIN0 or AIN1 is close to 2.45V.
Could you please give the advice on how they can resolve that issue?
Please ask me in case you need additional information.
Best regards, Dmitry Serbinov
FAE, Analog Devices, Inc. REP in Russia
attached files corrected
[edited by: rotax at 8:43 AM (GMT -4) on 12 Jul 2021]