• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 63 subscribers
  • Views 364 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Original question:

TPS65400: One of the outputs is wrong

TPS65400: TI K2L EVM schematics TPS65400 SW2 output is problem

sumathi m
Intellectual 905 points
Part Number: TPS65400

Hi,

We are using TPS65400 in our design. The circuit is exactly same as TI K2L EVM circuit.

The problem is we are getting 3.3V in the place of 1.8V. Tried changing the compensation values to 2200pf, 12k, etc. But the problem is same.

When we power on the SW2 output is around 1.5V initially and it is slowly increasing to 3.3V

Kindly advice any changes need to be done..in K2L EVM circuit???

Regards,

Sumathi

  • 0
    TI__Mastermind 19080 points

    Hi,

    Please check if the components are well soldered on board, and also same as required by the schematic. Are the other 3 channal channels working well?

    Can you post below waveforms here?

    1. Vout2 and SW2 in steady state.

    2. Vout2 and SW2 start up. 

    Regards,

    Hao

  • 0 in reply to Sam(MPAA) Zhang
    Intellectual 905 points

    Hi Hao,

    Thanks for the reply.

    Our problem is similar to the one in below link.

    https://e2e.ti.com/support/power-management/f/196/t/650140?TPS65400-One-of-the-outputs-is-wrong

    In this link the solution is not mentioned.

    I have already changed the comp R and C values as mentioned in the mail. But the issue is still there.

    In K2L Board different chip is used instead of TPS65400. Any reason for this change??

    Kindly reply ASAP.

    Regards,

    Sumathi

  • 0 in reply to sumathi m
    TI__Mastermind 19080 points

    Hi Sumathi,

    In that question, I guess the "Hardware problem" they mentioned might be wrong feedback resistors, wrong pin connection, etc... I don't think you have the same problem.

    The compensation R and C can make the loop stable, thus the output voltage is stabled. However, even the loop is unstable, the Vout would usually be oscillating, rather than ramp up to a higher voltage. This is why I'm asking the detail waveforms in previous post. At least, please help to capture the SW3 and Vout3 waveform. Thanks!

    Could you explain "In K2L Board different chip is used instead of TPS65400" ? I didn't get your point... Our EVM is using exactly the IC we are trying to evaluate through this board.

    Regards,

    Hao