20-Sep-2022
Attendees
Yichen Liu
@David Burnett
Daniel Lovell
@Yu-Chi Lin
@Alex Moreno
@Kristofer PISTER
@Austin Patel
Minutes
Daniel got ADC working
10th bit known sticking issue. TBD whether it’s an output problem (MSB not being routed correctly?) or input problem (strange issue with SAR state machine timing/control signals?)
vbat/4 looks stable, is functional
External input works
PTAT does not look so good, seems stuck at 255
some issues with determining absolute voltage
There may be some offset that needs to be characterized per-chip if we need to know absolute voltage. For situations that just need deltaV, we don't need that calibration.
offset is different by chip in part because ADC LDO varies per chip
@Titan Yuan's setup had a strange short between the LDO and external input
Typically 5ish LSB variance around samples. Not good but acceptable for the intended applicationsNext steps are to measure ENOB. Recommend using external clock initially to separate clock jitter error from circuit layout error
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