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UCC27512: Gate driver skipping every 3rd pulse at 300kHz

Santino Graziani
Prodigy 75 points
Part Number: UCC27512

I am using the UCC27512 gate driver chip (non-inverting layout) for a flyback converter design and it skips every third gate pulse when sending it control signals at 300kHz. I tried lowering the frequency to 100kHz which fixes the issue. I am using a F28335 Delfino Dev Board Kit to send the gate signals of 3.3V.

Summary:

  • UCC27512 Gate Driver Chip
  • 5VDD (this is also the power into the board that is supported with caps) [pin 3 VDD]
  • 3.3V gate signals at 300kHz from F28335 [pin 1 IN+]
  • Gate Resistor ~5ohm [pin 4 OUT]
  • Pins 2,5,6 are grounded 
  • Skips every third pulse 
  • Works at slower 100kHz

  • 0
    TI__Genius 13445 points

    Hello Santino,

    Thanks for reaching out.

    1. At 5VDD, you're operating very close to the UVLO rail, the driver supply might be deeping below the UVLO threshold. Please confirm that 5VDD does not fall below UVLO conditions which might be causing the skipped pulses. You can verify this by capturing VDD waveform directly from pin 3.

    2. Also ensure that you have decoupling caps directly at pin 3: paralleled C1 = 0.1uF and C2 >=1uF caps. 

    If you have a clean supply, and no improvement at 300kHz, please provide additional information below. 

    2. What is the gate charge that you're driving?

    3. Can you share schematic, waveforms

    4. Do the pulses skip at startup as well or after running for a certain period?

    Regards,

    -Mamadou