Push-Pull MOSFET Driver - Type 2 Gate Driver

469

07:53:34

A Push-Pull Gate Driver uses two complimentary BJTs to drive the gate of a MOSFET. Push-Pull Gate drives are used when the drive signal is coming from a source with a high output impedance or from a source having low output current capabilities, such as Op Amps. The two BJTs amplify the current coming from the signal source and push and pull a high current into and out of the gate of a MOSFET in order to turn it on or off quickly.

MOSFET USED: IRF540N.

If you want learn the need for gate drives, check http://everycircuit.com/circuit/5304891965440000

published 5 years ago

fatcat2

5 years ago

What's the point of that 10 ohm resistor? In my opinion, MOSFETs have junction capacitance in the range of pico farads.

PrathikP

5 years ago

@fatcat2 this isn't a matter of your openion. It is a fact. The junction capacitances shown are exactly what the IRF540N has.

PrathikP

5 years ago

And the point of the 10ohm resistor is to limit the charging current. A very high charging current can damage the BJTs and cause a dip in the line voltage. Both bad.

PrathikP

5 years ago

https://www.infineon.com/cms/en/product/power/mosfet/12v-300v-n-channel-power-mosfet/irf540n/ here is the link for the datasheet

fatcat2

5 years ago

I see. Thanks. Yup, I've checked the datasheet. Thanks for the information. But the duty cycle is too less. Then how could it damage the BJTs in the output side?

PrathikP

5 years ago

By duty cycle, do you mean the current spikes? Those spikes are not characterised by duty cycle. At higher gate drive voltages and for larger values of input and reverse transfer capacitance, the current spikes can be very large (like 1A or 1.5A) and stress the BJTs. Because of this, gate resistors are used.

fatcat2

5 years ago

All right

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