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Hello Everyone
I want to meaure 4-20ma and voltage come from a pot . I am using single supply 5Volt . should I connect analog inputs negative ( AIN) to 2.5V ( mid of supply ) or better to ground ( ov) ?
Thank you
Hello Hector,
Sounds like you're trying to differentiate between single-ended and puesdo-differential. I would recommend tying the negative input to mid supply, which would be puesdo differential. More info on the difference can be found in the TIPL video SAR ADC input types (which works for delta-sigma as well): https://training.ti.com/ti-precision-labs-adcs-sar-adc-input-types
With this device, the inputs are truly differential which means VIN is defined by V_INxP - V_INxN as shown in the table below.
If you tie the negative input to GND, and you have a signal from 4-20mA and 0V to 5V from a pot, then you're saying V_INxP will never be negative. As a result, you'll cut your Full Scale Resolution (FSR) in half as you'll never get a "negative code". If you tie the negative input to mid supply, then you can get negative and positive codes and effectively increase your Full Scale Range. More info on the math can be found here:
Best,
-Cole