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TPS63031: Vout is 1.1V when EN is low

Gabriel Lucas
Prodigy 230 points
Part Number: TPS63031

Hi everyone,

I am using several TPS63031 on a design to get 3.3V supplies. The EN pin of two of them is connected to the GPIO pin of a microcontroller and is pulled-down by a 10k resitor.

When the GPIO pin is configured to output LOW, the TPS63031 is giving an output of 1.1V while I am observing 0V on EN pin with a voltmeter.

Is there a particular GPIO configuration recommended to control the EN pin on a microcontroller ? Is the pull down resistor a problem here ?

Few more informations:

- PGND and GND are simply connected like in the example layout of the documentation so ground noise can be a thing here.

- The 1.1V output seems stable, even though I don't have accurate tools to confirm that. Furthermore, it is enough to keep supplying the load.

- The 3.3V output is working fine when the GPIO is output HIGH on the EN pin

- The input is fixed at 3.7V with a DC supply for now

Here are the schematics:

On the microcontroller side, the EN pin is directly connected to the GPIO, without any added component.

Best regards,

Gabriel Lucas

  • 0
    TI__Expert 7925 points

    Hi Gabriel,

    Thanks for reaching out.

    1. Could you please check the output voltage without anything connected to the output of the TPS63031?
    2. Could you check with a scope if there is any switching action on the L1/L2 pins when you put EN to zero?

    When disabled, the output of the TPS63031 goes high impedance and should be discharged by load. You maybe have something on the load side that is still pulling the output voltage high.

    Best regards,
    Milos

  • 0 in reply to Milos
    Prodigy 230 points

    Hi Milos,

    Thanks for your reply

    1. On the load side, and for the two supplies, all the pull-up circuits are using the TPS63031 output. But one thing I forgot is that the communication buses weren't correctly uninitialized. As the uC outputs 3.3V on its TX wires that are pulled-up by the TPS63031 output, a voltage appears on the supply output but isn't related to the TPS63031.

    So my bad for the issue, the subject is solved. Hope it will help others.

    Best regards,

    Gabriel

  • 0 in reply to Gabriel Lucas
    TI__Expert 7925 points

    Hi Gabriel,

    Thanks for the update, we're glad you solved your problem.

    Best regards,
    Milos