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Glitches on LPCOMP

FormerMember over 8 years ago

Greetings,

I'm working with LPCOMP to detect a signal. This signal is the output of an opamp amplifier. What is happening is that when the LPCOMP is switched on there are periodic glitches on the OPAMP output every 1.98 s as seen below. The peak to peak voltage of these glitches are about 0.1 V.

OPAMP signal to LPCOMP pin

To investigate this we disconnected the OPAMP output from the nRF51's pin which is configured as LPCOMP input and left it floating. Now the OPAMP output does not have any glitches. And what's happening in the floating LPCOMP pin? There are huge glitches every 1.98s as in the pics below.

floating LPCOMP pin

floating LPCOMP pin zoomed in

So it looks like the LPCOMP pin is generating some weak signal periodically which is affecting the signal fed to it. Has anyone observed anything similar? Any thoughts on why this might be?

Cheers, Prithvi

0 Øyvind Karlsen over 8 years ago

Need some more context here. Is this on a custom board, if so are you routing this next to a line that is potentially noisy? What kind of code are you running when you see this behaviour?
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0 FormerMember over 8 years ago

Forgot about the battery measurement algorithm running also. The shared analog mux was causing this issue. My bad. Please feel free to delete this question.
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