When using SIO for VBus monitor pin, is it ok to use resistive pulldown drive mode?

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KeYp_290406
Level 4
Level 4

The default mode is high impedance but this doesn't work well with a self powered device. If you pull the USB connector it can take a long time for the VBus line to drift low. It's a legal selection for the pin but don't want to cause any unwanted issues although I think an SIO is fairly hardy.

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KeYp,

It should work with virtually all USB ports.

If you're willing to use a PSoC5 comparator, you can detect when Vbus drops below xxx volts and launch a ISR to detect when the USB is disconnected and when Vbus rises above xxx volts you can launch an ISR to detect when the USB is connected.

This prevents the need to connect VBus to a ADC and for the ADC to scan/poll the VBus voltage.

Len

Len
"Engineering is an Art. The Art of Compromise."

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