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Topic: Tension on shutted down gpio (Read 2 times) previous topic - next topic

retrolefty

Yes, I would give simple series resistors a shot. However I'm not sure 1K is the right value, you want to prevent current in excess of what the clamping protection diodes are rated for. I suspect 10K or more is more suitable, maybe more? The datasheet should give clamping diode ratings somewhere I would think?

Lefty


dhenry

Those diodes are rated 20ma. It would take over 200v to kill those diodes + 10k resistor.

Not to mention the low-pass filtered you got there.

MarkT

The protection diodes are rated at 0.5V max forward bias - that's rather less that 20mA I think - or have I missed the right part of the specs?

Actually specifying the voltage is a rather poor way of doing this as forward voltage varies significantly across the operating temperature range.
[ I won't respond to messages, use the forum please ]

Docedison

Yeah they make good thermometers, easy to calibrate but do require a 2 point cal for <5% accuracy.

Bob

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dhenry

Quote
as forward voltage varies significantly across the operating temperature range.


-2mv/c, pretty much.

How many degrees of temperature do you consider "significant"?

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