• State Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 63 subscribers
  • Views 343 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.

LM5152EVM-BST: LM5152EVM-BST, why is 7V Input required to start-up the Eval kit

Julia Johnson
Prodigy 20 points
Part Number: LM5152EVM-BST

I am using a LM5152EVM-BST EVAL kit, and I would like to change the design to not require 7V to startup.

Why does the LM5152EVM-BST need 7V to startup?

Does the LM5152QRGRRQ1 require 7V to startup? OR does the bias>= 3.8V condition just need to be met.

  • +1
    TI__Guru 58661 points

    Hi Julia,

    thank you for using the E2E forum.

    The startup is set to ~7V with the voltage divider on the UVLO/EN input of the LM5152. With this voltage level it is ensured that the internal LDO for the Vcc generation always has a high enough input voltage to properly start up and provide the supply voltage for driving the MOSFET gate signals.

    Lowering this voltage is of course possible but ensure that the drivers for the MOSFET get a high enough voltage during the startup phase.

    In this case the EVM is used to target the cold crank. In that case the Voltage drop during the start of the engine should be compensated. So at the beginning a higher voltage is already available and the EVM can power up. When then the voltage drops, it kicks in and maintains the output voltage.

    Best regards,

     Stefan

  • +1 in reply to Stefan Schauer
    TI__Guru 58661 points

    Hi Julia,

    I have not seen an update for the last 10 days, so I assume the questions are/or answered and the issue is solved.
    I close this thread now. If there is still something open reply and the thread will get open again.
    If you have any other question or of the thread gets locked, please open a new one.

    Clicking the Resolved Button also helps us to maintain this forum.

    Best regards,
    Stefan

  • 0 in reply to Stefan Schauer
    Prodigy 20 points

    Hi Stefan,

    I changed the UVLO threshold using the TI calculator tool and the board was able to run off a voltage of 4.2V.

    Thanks for your help!

    Julia