Other Parts Discussed in Thread: ADS1220, LM3480
Hello, hope you are doing well,
I am designing a custom PCB based on the BQ25703AEVM. I am adding an ADS1220 ADC to this design and I was wondering about the best practice for powering and grounding this ADS1220. I am using the ADS1220 for unipolar measurements, and I have a 3v3 buck power supply on an external board in addition to the LM3480 which is part of the BQ25703AEVM design. The BQ25703AEVM schematic has two ground symbols: PGND and GND, which should be connected in star topology with PGND. I'm going to refer to GND as AGND for clarity.
Am I correct in thinking I should use the LM3480 and AGND to connect to AVDD and AVSS on the ADS1220? I checked the LM3480's datasheet to check for a current limit, and could only find reference to a 100mA minimum load current. I suspect that the BQ25703AEVM design draws much less than 100mA from the LM3480, which makes me think that the increased load would actually bring the LM3480 closer to nominal operation (but the ADS1220 draws so little current I don't see it making much of a difference either way).