Hi Daniel, Welcome to TI E2E forum. 1. Option 4 is recommended because it has a better filtering and a balanced input that can eliminate the additional offset error when the input current is flowing through the resistors. The FAQ is a good guideline for RC component selection: [FAQ] Delta-sigma ADC anti-aliasing filter component selection 2. Yes, you can measure it on REFIN pin, but it is around 1.2V. 1.25V is the typical external reference voltage. The internal reference voltage is intended to design for the data conversion on the ADC, it is not recommended for external circuit unless a buffer is used. The external capacitor on the REFIN pin is just filtering the internal bandgap noise, so it can be removed. The capacitor is not recommended especially in the current detect mode because adding external capacitor will make the startup slow. 3. An external 1.25V precision voltage reference is recommended because the resistors will introduce noise and also shift over temperature. You can find TI 1.25V voltage reference here . BR, Dale
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