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please forgive me for my bad English. I am using ATMGA328P MCU to control ignitors which needs about 500ma current to work. To provide such current, I use AO3400A N-MOS to control the ignitors. In early design, I didn't use pll-down resistors. The N-MOS can ignite ignitors when MCU outputs 5V on its gate. However ignitors maybe ignited unintendly when power on(MCU is reseting during this period of time, IO is unstable). So I put 1M pull-down resistor on the N-MOS's gate which provide 0V when MCU in reset. It successfuly avoid unintended ignition. But I found the N-MOS can't ignite ignitors anymore when MCU outputs HIGH.

My questions is: Why such large resistor makes the N-MOS can't work? According to the datasheet of the MCU, its IO can provide maximum source current of 40ma. In my view, it's quite large, which means 1M resistor won't reduce IO's drive capability on the N-MOS's gate.

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  • I’m voting to close this question because SO is a programming Q&A platform and this question is not about programming. [What topics can I ask about here?](https://stackoverflow.com/help/on-topic) – Rob Jul 24 '21 at 10:09
  • Welcome to Stack Overflow. Please take the [tour] to learn how Stack Overflow works and read [ask] on how to improve the quality of your question. Then check the [help/on-topic] to see what questions you can ask. You might want to delete this question and ask it on https://eletronics.stackexchange.com/ instead, but check the help pages there first. – Progman Jul 24 '21 at 10:50

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