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Original question:

TPS51220: Asking for TPS51220 design review and suggestions

TPS51220: Output 4.92V rather than 5V

Betul Aktepe
Prodigy 130 points
Part Number: TPS51220

Hi we use schematic from datasheet we try to get both 3.3V and 5V output. We can get 3.3V output but, when we measure 5V output it gives 4.92V.

Our next question is, when we touch on components near TPS51220A it stops output. If we do nothing output does not give voltage. If we LOW enable and wait 1 second and HIGH back again, it start giving output. Is that normal? Thanks for your help.

  • 0
    TI__Guru 52245 points
    Betul Aktepe said:
    Hi we use schematic from datasheet we try to get both 3.3V and 5V output. We can get 3.3V output but, when we measure 5V output it gives 4.92V.

    Please double check the FB1 to GND voltage at the IC.  The FB voltage should be 1V.  If the FB pin is 1V and the Output voltage is 4.98, please check ground at the output voltage sense and the GND back at the IC.

    Also check the voltage drop across each resistor.  Are these 1% tolerance resistors?

    Betul Aktepe said:
    Our next question is, when we touch on components near TPS51220A it stops output. If we do nothing output does not give voltage. If we LOW enable and wait 1 second and HIGH back again, it start giving output. Is that normal?

    The TPS51220A implements latching faults.  If pressing on the part or nearby components nearby are triggering a fault condition, such as OV or UV, the output will shutdown and will not restart until Enable is toggled low then high.