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TPS53319: device failure

Kazuhiko Hirano
Genius 14918 points
Part Number: TPS53319

Hello,

My customer is using TPS53319 for their design.
After power up, their load current starts increase intermittently.
Then some TPS53319 (they call this good device) work correctly, but some TPS53319 (they call this NG device) stop working, Vout drop..
Please see the following xlsx file.
tidrive.itg.ti.com/.../6405b179-8bb7-48d2-9e00-3f49456c9aea

Page 1 shows their schematics, TPS53319 works as FCCM.
Page 2 shows Vout(ch1), Power Good(ch2) and Iout(ch4) for a good device and NG device.
Page 3 shows Vout(ch1), Power Good(ch2), VFB(ch3) and Inductor current(ch4).
The Vout drop is fixed with additional 200uF Cout somehow.

Please advice what is going on at the NG devices and explain the root cause.
Also explain why the additional 200uF Cout can fix the issue.

 

Best regards,

 

K.Hirano

  • 0
    TI__Mastermind 23695 points

    It looks as though the OVP is triggering.     When OVP triggers, the hs fet turns off and the low side turns on until the voltage is below the UVP threshold. 

    Adding the 200uF, minimizes the Vout overvoltage.      

    Check the FB pin during the measurements and check if the voltage is exceeding 720mV. 

    One method to troubleshoot the OVP theory, would be to add a small capacitor across the low side feedback resistor on the NG device without the 200uF capacitor.

    The small capacitor should act as a filter and prevent the FB voltage from exceed 120% 

  • 0 in reply to David_Daniels
    TI__Genius 14918 points

    David,

    I, see, thanks a lot!

    Besr regards,

    K.Hirano