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LM74700-Q1: MOSFETs-parallel

Tobias Unger
Prodigy 10 points
Part Number: LM74700-Q1

Hello,

I would like to ask if I can use the LM74700-Q1 to control two or three MOSFETs parallel to reduce the Rdson?

And if I can use one LM74700-Q1 to control two MOSFETs I would need Vias to connect the gate of the other MOSFETs.

What are the effects of using Vias because in the data sheet is written that I shouldn´t use Vias?

Yours sincerely

Tobias Unger

  • 0
    TI__Genius 16305 points

    Hello Tobias,

    Yes, you can use LM74700-Q1 to drive more than one MOSFET.

    But we would suggest to understand the turn on time based on the gate capacitance of the total MOSFETs in parallel.

    This device maximum peak gate drive current is about 11mA and turn on time T = C_gate * (Vth_MOSFET) / 11mA. Note that until the MOSFET turns ON, body diode would conduct the current (inrush due to large capacitance after MOSFET).

    Concern regarding the vias is that, during turn off the MOSFET gate is pulled down to anode by 1.5A of gate current. Long routing or vias in the path can add inductance and that should not cause ringing high enough to cross Vth of MOSFET, which accidentally turns on.

    Calculate the trace inductance and via inductance and if it doesnt exceed few nH it should not be a big concern.

    Also we recommend to add 10 ohm of gate resistance in series to avoid ringing.

    Regards,
    Kari.