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UCC24612: UCC24612 effectiveness

James Su5
Expert 1340 points
Part Number: UCC24612
Other Parts Discussed in Thread: LM5021, , UCC24630

For PWM LM5021 flyback + SR IC UCC24612-1 effectiveness compare with SP6019 at Vin 24V / Vout 5V / Po 30W condition, UCC24612-1 CRGE is 2.2uF. 

LM5021 + SR IC UCC24612-1 effectiveness 84.67%

LM5021 + SR IC SP6019 effectiveness 89.3% 

Compare each VDS and VGS wave from, UCC24612-1 VGS drop around 3V by each duty end, But SP6019 VGS can keep around 8V in full duty, how to improve ?

Thanks and Best Regards

James Su

  • 0
    TI__Mastermind 40120 points
    Hello James,

    The UCC24612 uses proportional gate-drive voltage adjustment to reduce Vgs during half of the SR on-time as you show in the waveform. The purpose of this is to speed up the turn-off of the SR FET in DCM and light CCM applications. I suspect that your application is working in deep CCM, and that some reverse shoot-through current happens when the SR FET is turned off. I believe that this is the true cause of the lower efficiency when using the UCC24612-1.

    The SP6019 controller turns off the SR FET before the end of the demagnetization time so that reverse shoot-through current is avoided. I suggest to evaluate the UCC24630 SR controller for your application. This controller uses a similar early turn-off technique like that of the SP6019 and should provide the same level of efficiency. Please consider the UCC24630 device here: www.ti.com/.../UCC24630
    You can order samples at the "Order Now" tab of the various folders shown there.

    Regards,
    Ulrich
  • 0 in reply to Ulrich Goerke
    Expert 1340 points

    Hello Ulrich,

    UCC24612 What's Topologies efficiency can Better than SP6019 ? Active Clamp, Flyback, QR, DCM, CCM Flyback and LLC ?

    Thanks and Best Regards

    James Su