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Topic: Will turning off the MOSFET turn off boost driver? (Read 2465 times) previous topic - next topic

wyager

I'm working on a project (nixie clock) that involves a high voltage boost converter-from 9V to 170V. The boost driver is basically this:

But with a bigger inductor (2200┬ÁH) and a completely different controller design. Anyway, part of what I want to do is to be able to turn off the boost circuit via software. If I were to turn off the MOSFET, would this effectively turn off the boost converter? Ideally, I would just disconnect all the nixie tubes and leave the boost driver running, but the way I understand it this would only cause the inductor to shoot the output voltage way up (due to the lack of any appreciable current draw) and damage the circuit.

retrolefty

I can't really comment on the circuit as a whole, however I can state that a IRF730 mosfet is not a logic level mosfet and thus will not completely saturate on with a 5v signal from a arduino output pin.

You need a mosfet designed for 5vdc gate service, although I don't know how many are avalible to run at higher voltage drain condition that your circuit would develop.

Lefty

westfw

Well, if the mosfet is off, you'll eventually get the input voltage flowing through the inductor to the output, so Vout will be the same as Vin.  I would call that "off", if your nixie needs 180V to conduct at all...

wyager

@retrolefty
Thanks, I have a "totem pole" transistor setup driving the MOSFET. The driver works fine as of now, I just need it to turn off.
@westfw
Thanks, that's what I assumed.

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