[SOLVED] pull up value on signal that has driver

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sebas

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Hi,

I see that there are a lot of schematics where there are pullups on pins that also have a driver. Can you do this with any signals (i usually see it on reset signals)? How weak has the pullup so the driver can still make the signal 0?

Thanks
 

Look at your driver spec VOL condition, usually milliamps of load. Below
this it's guaranteed to make VOL. You may not need to pull that much.
It wastes power. Pullups can help deal with things like what happens to
that "output" signal (your input) during power-up where FETs might be
too weak to assert a proper state, the pin goes intermittent or open,
etc. They generally don't have to be very stiff, just "suggest the right
answer".
 
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