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LM74670-Q1: Gate drive pull down current during rectification

Gregory Duperon
Expert 7470 points
Part Number: LM74670-Q1

If we're using this device in a half-wave rectifier configuration, the 160mA pull down current needed to discharge FET gate capacitance will be triggered every negative half cycle, correct?

Looking at the block diagram for the part, it isn't clear where this current is being sourced from?

Is there an internal current source in the Reverse Batt Shut Off block?

Thanks.

  • 0
    TI__Genius 16305 points
    Hi

    When the controller detects negative polarity during the negative cycle of AC sinusoidal, the Pull-Down quickly discharges the MOSFET gate through a discharge transistor. Discharge strength is 160mA for Vgate_pulldown = Vanode + 2V.
    Basically, pulldown strength is 160mA and it determines how fast gate is discharged (depends on gate cap).

    There is no internal current source as such, but there is a strong pulldown transistor whose pulldown stength is 160mA at 2V overdrive (Vgate_pulldown = Vanode+ 2V). This transistor is present in the Reverse Batt Shutoff block.

    Regards,
    Kari.