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TPS65279V: Is it possible to get 3.3V at output with 5V at input?

Janis Sarikas
Prodigy 155 points
Part Number: TPS65279V

Hello,

we tried to use the TPS65279V with input voltage of 5V to get 3.3V@1.4A out of Port 1 and 1.8V@0.2A out of Port 2.

We are not using the I2C interface but external resistor dividers. 

Unfortunately on our prototype only 1.8V at port 2 works but port 1 stays at 0V. 

We measure the following voltages on the enable pins and soft start pins:

  •  EN1, EN2: 1.5V
  •  SS2: 2V
  •  SS1: 0V

We are wondering about the 0V at SS1. Could this be an issue or is it simple not possible to get 3.3V with 5V input? 

Here is a copy of our schematic. 

Best regards 

Janis

 

  • 0
    TI__Mastermind 21220 points

    Hi Janis,

    Thanks for reaching out. I will check and give you response soon. Thanks!

    BRs

    Lucia

  • 0
    TI__Mastermind 21220 points

    Hi Janis,

    There is no problem to get 3.3V from 5Vin. It's not make sense to see SS1 to be 0V. Could you please first check whether it is soldered well? Please also check the voltage of FB1 pin. Then, you can set port2 as 3.3V since 1.8V port 2 can work well and for TPS65279V, buck1 and buck2 works similar. If port2 can set as 3.3Vout and work well, it should be no problem to set port1 as 3.3V

    Thanks!

    BRs

    Lucia

  • 0 in reply to Lucia Gao
    Prodigy 155 points

    Hello Lucia, 

    thanks for your reply and please excuse me for my late answer. We already solved the problem one day later and forget to post it here. 

    There was a short on our prototype between 3.3V and GND. This was due to 0-ohm bridges for pulling up or down some strapping pins of other ICs on the board. Unfortunately we didn't mark them right and our assembler placed both of them to some pins. After we soldered them of the converter worked fine :)

    Best regards 

    Janis

  • 0 in reply to Janis Sarikas
    TI__Mastermind 21220 points

    Hi Janis,

    No worries. Thanks for you update and glad to here that the problem has been fixed!

    Let us know for any further concern!

    BRs

    Lucia