I am looking at putting a single pole RC filter (with around 100Hz cutoff I was thinking and design of ()) on the input to the SD16 channels of a MSP430F427A, and was wondering about the drawbacks of doing this. In the family datasheet it recommends a external RC filter however in another TI application note (ftp.ti.com/.../sbaa111_Understanding_MSC12xx_ADC_Input.pdf) it suggests there are some offset and delay issues associated with putting an RC filter on the un-buffered input of a delta-sigma ADC, do you think that this would be an issue for the SD16?
Another question I wanted to ask was concerning the use of ground as one of the inputs to the ADC, as I am measuring the voltage drop across a precision current shunt (for a coulomb counting battery monitor) which is connected to battery negative and the other end is used as system ground. I have read in these forums that using ground as an input to the differential ADC can make it quite noisy, is there an obvious workaround to this situation?
Thanks