PMU I2C 47K Pullups not great (part 1)

Andy Green andy at
Mon Feb 4 19:02:37 CET 2008

Hash: SHA1

Hi folks -

47K SCL and SDA pullups R1707 and R1708 were chosen which are pretty
high for 400kHz I2C.

They make a less than ideal-looking situation for SCL (image 8) and a
even less great situation for SDA (images 6 and 7).

You can see on image 7 the high pullup impedence allows another signal
to couple to SDA.

I dunno if it actually makes any of the PMU issues or not, but it would
be okay to reduce these to 10K... they will only pull current while
something drives the line low, the vast bulk of the time those lines are
floating anyway.

Going to see if I can alter mine to that.

- -Andy
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Comment: Using GnuPG with Fedora -

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