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UCC21520: UCC21520 output waveform incorrect

Wayne Chiu
Prodigy 460 points
Part Number: UCC21520

Tool/software:

Hi Team, 

We found that the output waveform of the UCC21520 at the start-up has some abnormalities on the upper arm. What are the possible causes and ways to improve?
Please see the attachment
Full-bridge architecture
CH1,2 for lower arm output; CH3, 4 for upper arm output
CH1, 4 for left arm output; CH2, 3 for right arm output

The filename screenlmg (44) wave pattern is normal but not happened often
Most are shown as screenlmg(45) even as screenlmg(46)
We have confirmed input signal is normal and power supply is normal too.

screenlmg (44)

screenlmg (45)

screenlmg (46)

  • 0
    TI__Expert 8686 points

    Hi Wayne,

    Thank you for providing all of these details!

    I have a few questions to better understand the issue being seen:

    • Does the issue follow the device after ABA swapping?
      • If it does, is there a condition that consistently triggers the issue?
    • Would you be able to share the schematic/layout?

    Looking forward to hearing back.

    Regards,

    Hiroki