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TPS65261: The 29pin(VIN) short circuit to ground

Eric Mo
Intellectual 775 points
Part Number: TPS65261
Other Parts Discussed in Thread: TPS65251

Hi Team,

Our customers have design problems with TPS65261. He uses three TPS65261 to reduce the 12V voltage to 3.3V (three channels) and 1.8V (two channels). One TPS65261 only uses one output ( 1.8V is not connected to the load), which is easy to short circuit the 29PIN(VIN) of tps65261 to ground. Could you please help to check and let us know the reason?

Thanks and regards

  • 0
    TI__Genius 17390 points

    Hi Eric,

    Thanks for reaching out to us.

    1. Do you mean that customer uses three TPS65261. The first one uses two Buck output(3.3V, 1.8V), the second one uses two Buck output(3.3V, 1.8V), the last one uses one Buck output(3.3V)? However, for the last one, 1.8V output is still shown in the schematic and layout, but not connected to the load. Not sure whether I understand correctly or not.

    2. Do three TPS65251 use the same schematic and layout? Why don't the customer use 2 TPS65261 since each TPS65261 has three channels?

    3. What is about TPS65261 which uses two outputs? Do they operate properly? Do Vin short to ground only occur for the last one which uses only one Buck output? How does the customer realize this disconnection? What is the failure rate of this kind of VIN short to ground?

    BRs

    Lucia

  • 0 in reply to Lucia Gao
    Intellectual 775 points

    Hi Lucia,

    Checked with the customer again. The first uses three step-down outputs (3.3V, 3.3V, 1.8V), the second uses three step-down outputs (3.3V, 1.8V, 1.8V), and the last uses one step-down output (3.3V). The 1.8V output is still displayed in the schematic diagram and layout, but is not connected to the load. The first two application outputs are normal.And Vin short to ground only occur for the last one.

    Thanks and regards

  • 0 in reply to Eric Mo
    TI__Genius 17390 points

    Hi Eric,

    If Buck2 and Buck3 are not used and PG function is not needed. Please make sure that EN2 and EN3 are tied to GND. Other pins of Buck2 and Buck3 can be floating.

    BRs

    Lucia