• State TI Thinks Resolved
  • Locked Locked
  • Replies 5 replies
  • Answers 1 answer
  • Subscribers 64 subscribers
  • Views 428 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

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.

LM5146-Q1: Request a Review the Design of LM5146

Louis Han15
Genius 4680 points
Part Number: LM5146-Q1
Other Parts Discussed in Thread: LM5146, CSD19502Q5B, CSD18563Q5A

Hello

Could you review the attached design?

Design Condition

  • V Input: 48V
  • Switching Frequency: 400KHz
  • V Output: 5.078V
  • I Output : 10A

I Attached LM5146-Q1 Quickstart Design Tool & waveform file.

LM5146-Q1 Quickstart Tool r2 - 48Vin 5.07Vout 10A 400kHz.zip

Best regards.

  • 0
    TI__Guru 66042 points

    Hi Louis,

    Here are some comments:

    Tie NC pins to GND for better GND plane heat spreading from the IC.

    Use the derated value for ceramic Cout in the quickstart and update the compensation values accordingly. Also, set the inductance at 3.3uH.

    What are the MOSFET part numbers? Consider using 60V NexFETs if Vin-max is 48V, e.g. CSD18564Q5A or similar.

    Set current limit at 15A for some margin for load transients, MOSFET Rdson variation, etc.

    Regards,

    Tim

  • 0 in reply to Timothy Hegarty
    Genius 4680 points

    Hi Tim

    Thanks for your support.

    MOSFET Part number is CSD19502Q5B.

    Inductance is 3.3uH.

    Best regards.

  • 0 in reply to Louis Han15
    TI__Guru 66042 points

    Thanks, Louis.

    That MOSFET is somewhat capacitive at 400kHz - you can use a more efficient 60V FET if needed.

    Regards,

    Tim

  • 0 in reply to Timothy Hegarty
    Genius 4680 points

    Hi Tim

    The attached schematic generates thermal during the no-load operation test.

    The thermal is generated from the low side FET and is confirmed to be over 60℃.

    could you tell me how to solve this problem? 

    Best regards

  • 0 in reply to Louis Han15
    TI__Guru 66042 points

    Hi Louis,

    The FET is too capacitive, hence the high no-load losses. Please try a more suitable FET for this application. Ideally, 60V provides much lower losses, e.g. CSD18563Q5A.

    Regards,

    Tim