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CCS/PMP9522: How to increase maximum current

ACGUY
Guru 11170 points
Part Number: PMP9522

Tool/software: Code Composer Studio

Hello E2E,

I want to include the like Solid state relay circuit by semiconductors for next product. It will has 200-A peak current instantly.
I found the PMP9522.
I'd like to use and modify the design. Can I have advice from TI?

If it made increase maximum current, it should to use very Low Ron FET. But it has high Qg.

If this design uses FETs with high Qg or in parallel, do I need a high current driven Gate-Driver?

Best regards,
ACGUY

  • 0
    TI__Intellectual 2770 points

    Hello ACguy,

    the push pull controller UCC2808 just provides the gate voltage across pulse transformer;
    at Q1/Q2 it's not a typical kHz gate drive for SMPS here.

    Means, such a relay, mechanics ore solid state, doesn't work in the kHz area,
    these FETs are in almost "static" ON/OFF mode.

    I'm pretty sure you could use stronger FETs, so less RdsON and even more Qg.
    UCC2808 switches open loop at 200kHz out of pre regulated input 12V w/ constant duty,
    generating basically Vin = Vout - but providing isolation across pulse transformer T1.

    As soon as you enable the controller the internal gate drivers are switching on the transformer windings,
    generating the 12V on secondary side, this Vgs is switching Q1/Q2 ON.
    Disabling the controller stops switching, 12V drops, R4 100k discharges the gates, Q1/Q2 OFF.

    So the output voltage of the tiny SMPS is just switching Q1/Q2 ON and OFF;
    this circuitry will work for stronger FETs as well.

    Best regards, Bernd