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TPS23753A: Issues with overheating and output

Louiza Loizou1
Prodigy 120 points
Part Number: TPS23753A

Hello, 

I hope you are well. 

We have implemented the TPS23753EVM-004 onto one of our designs but it doesn't seem to work as expected. The input seems stable enough when powered (screenshot 1) but on the output we can only see about 0.6V (screenshot 2) and the switching FET overheats. I've probed the gate of the FET and the voltage swing is excessively large (screenshot 3). 

I have traced the schematic twice and I can't see any differences between the development board and our design. Could you please review the screenshots below and let me know if you have any ideas as to how to debug this? I'm happy to send our schematics on a private ticket. 

Thank you. 

Kind Regards, 

Lou

  • 0
    TI__Mastermind 21320 points

    Hello Lou, 

    Please accept my connect request to enable private messenger. Please send me the schematic for review. 

    If the schematic does perfectly match the EVM, then it is either a layout issue or an incorrect component. Something could be connected improperly in the layout, causing this behavior. Or something could be broken, and causing other things to break. 

    I almost wonder if it is the transformer...the input voltage is typically 48V, and if you're supposed to be stepping it down to 3.3V but instead see 484V.... its like stepping up the voltage by 10x instead of stepping down by 10x...I would check into the transformer first. 

    If this post answers your question, please indicate so by marking this thread as resolved. Thank you.

     

    Regards, 

     

    Michael P.

    Applications Engineer

    Texas Instruments 

  • 0 in reply to Michael Pahl
    Prodigy 120 points

    We've identified the issues - we had to change the following in our design: 

    • FRS resistor - from 118k to 59k 
    • BLNK resistor - from 162k to 80k6
    • CS resistor - from 0R to 100R
    • GATE resistor - 24R9 from to 35R