treitmey
Member level 1
I have a relay that is driven from a PIC 18F452.
It is driven with a FDV301N N-FET.
I've put a 10k in series with the uC pin to limit current to the FET.
NOW I want to put a pull-down on the pin for when the micro-controller is in
reset and the pin is set as input. so I don't want the input to float, So I want to
put a pull down on it.
My question is should the pull down go before or after the 10k that is there,..
and what should the resistor values be.
My thinking is that if a resistor is at the Micro controller pin, and that pin is set high, then
there is going to be a voltage divider. +5,Res1,Res2,Gnd, and that the FET won't
see the +5V. What is the math that I should use to calculate the resisters.
https://www.fairchildsemi.com/ds/FD/FDV301N.pdf
It is driven with a FDV301N N-FET.
I've put a 10k in series with the uC pin to limit current to the FET.
NOW I want to put a pull-down on the pin for when the micro-controller is in
reset and the pin is set as input. so I don't want the input to float, So I want to
put a pull down on it.
My question is should the pull down go before or after the 10k that is there,..
and what should the resistor values be.
My thinking is that if a resistor is at the Micro controller pin, and that pin is set high, then
there is going to be a voltage divider. +5,Res1,Res2,Gnd, and that the FET won't
see the +5V. What is the math that I should use to calculate the resisters.
https://www.fairchildsemi.com/ds/FD/FDV301N.pdf