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LM5023: Check the Gate Off issue

Louis Han15
Genius 4680 points
Part Number: LM5023

Hello

There is a problem that the LM5023's Gate is momentarily turned off during operation.

I attached the schematic and waveform

Condition : Vin - 90V, Load - 40W

Condition : Vin - 90V, Load -35W

Increase the Vin voltage or reducing the load will remove this problem.

Could you please check this problem?

Best regards

  • 0
    TI__Guru 66135 points

    Hello,

    I reviewed your schematic and it looks like the QR pin is not setup correctly.  You may have excessive noise on the QR pin causing this behavior.  Please follow the guidance for setting up the QR pin first to see if it resolves the issue.

    If changing the QR setup does not fix this behavior the next step would be study study QR, COMP, VDD and CS pins during this behavior.  If the QR is extremely noise it could cause this behavior. 

    If it ends up being a noisy QR signal.  You might be able to fix it with filtering on the QR pin with a filter capacitor.  If that does not work the next step would be for you to evaluate the layout to make sure it is not contributing to the issue.

    The LM5023 data sheet gives layout tips on page 29 and layout example on page 30 figure 25.  You may find this useful in evaluating your layout.

    Regards,