![]() In slow applications like this, the gate resistor (gate stopper) prevents the NMOSFET from oscillating due to the NMOSFET's high frequency response and relatively large parasitic capacitances. If you really want to reduce static drain current there are techniques to do this but the circuit would be more complicated. But I would be inclined to find another NMOSFET with lower gate/substrate leakage current if you want to use a higher value of pull up resistor to reduce static current consumption. So a 100k pull-up resistor may only pull up to 4V rather than 5V which would still be OK. Hi jnz, The value for the pull up resistor is limited by the gate leakage current, which for the RU1J002YN small signal NMOSFET is quite high at +-10uA. Is there a general rule for acceptable mosfet gate bias resistor values? Just how weak can I make this pullup? Can I "get away" with 200k? I don't know the line capacitance so I assume I can't really determine this effectively. This is more than 1/2 the "sleep" current I'm shooting for. How do I determine an appropriate value for the gate resistor? Bias resistor: Next, when I turn this mosfet off by grounding the gate, I'll be leaking 50uA into the ground keeping the weak pullup down. I won't ever see the mosfet as "ground" because it'll never be unpowered, the biasing weak pullup is there. So if I have a 5V micro that can source 20mA, I want something like a 250ohm resistor here to stay at that limit so long as the switching speed is acceptable So. For gate protection, but as I understand this it's more micro protection because an unpowered mosfet will appear like ground to the micro for a short moment and the gate resistor is to slow this process down. Something like this small transistor: ] Gate resistor: I think I need a gate resistor on the right side of the pullup closer to the mosfet. I have up to 100mS to switch when it needs to happen. I'm trying to hold that 5V DEVICE pin low all the time except when the micro decides otherwise, including the scenario the micro is not powered or has no code. I found a really long stackexchange post on this, and some other data but got lost in the weeds.
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