- Joined Nov 15, 2019
Is it possible to use an IC like the LM324-N To drive a mosfet for an inverter circuit?
The LM324, in addition to not having high drive capability, also has a very low slew rate (it's slow), making it a very poor choice as a gate driver. Yes, you could place a transistor stage (common emitter only) between the LM324 and the gate, using the transistor to pull the gate to 0V and using the collector resistor to pull the gate high...but you won't get very high speed that way. You could also drive a real gate driver with the LM324 and--provided you don't want to switch at a very low frequency--drive a gate from the gate driver. None of those schemes is good; the LM324 is simply too slow to drive a MOSFET gate in any inverter operating at a reasonable speed. Unless you only need to switch at 50-60Hz, don't use the LM324 to drive a gate.Can I include an external transistor to increase the amperage?
You can, but you still won't be happy with the results. What you need is a push-pull class AB compensated circuit that will move large amounts of charge onto and off of the gate.Or a circuit like this?
As always - you should check the datasheets to determine how much base current you need to supply to get the required collector current. If 20 mA is the max current your amplifier can supply then you'll need a gain of 100 to get from 20 mA to 2A.Ok. That means the circuit arrangement will be from:
AMPLIFIER - GATE DRIVER - CIRCUIT. Right? By the way, thanks for the recommendation.
Looking at the datasheets I don't think a gain of 100 would be reasonable for those transistors. Looks like something in the neighborhood of 20-40 so maybe we need to consider alternatives. You could get more gain using a Darlington Pair, but you would need two diodes in each leg to compensate for the 1.4V Vbe drop, Or you could keep searching for transistors that can switch the MOSFET gate with a smaller current than 2A.As always - you should check the datasheets to determine how much base current you need to supply to get the required collector current. If 20 mA is the max current your amplifier can supply then you'll need a gain of 100 to get from 20 mA to 2A.
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by Luke James
by Jake Hertz
by Jake Hertz
by Jake Hertz