• State
  • Locked Locked
  • Replies 3 replies
  • Subscribers 63 subscribers
  • Views 174 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.

LM5164-Q1: Thermal issue

Ivy Jin
Intellectual 2660 points
Part Number: LM5164-Q1
Other Parts Discussed in Thread: LM5146-Q1

Hi team,

My customer use LM5146QRGYTQ1 in their project, and they found the LM5146-Q1 will produces high temperatures during normal operation.

Below are the schematic and Temp test results. Could you please help review and give some suggestions?

Besides, we also have below questions, could you please help to give some comments?

1. Is the chip heating issue related to the D1 diode?  and must D1 be added?

2. The reference design of the EVM board is a 4-layer circuit board, and if the customer uses a 2-layer circuit board with full DC-DC load, will this have a significant impact?

3. Are there any special requirements for the parameters for the external MOS?

Schematic

7801.Power Supply.pdf

Master Controller Temp. Rise.xlsx

Thanks for your support!

Regards,

Ivy

  • 0
    TI__Expert 6565 points

    Hello Ivy,

    The diode is there to prevent reverse feedback into the Vin node from the Vin pin for the device. This will happen if the voltage being supplied into Vin goes lower than the Vcc bias rail. Unless your power source requires this specifically, then that would be unnecessary. Furthermore this should not cause intense heat.

    The schematic looks to be functional. Please make sure that each component was properly soldered onto the PCB. I see no requirements from the datasheet regarding an external MOS.

    If the customer is using a 2 layer circuit board instead of the standard four, this could have dramatic impact on the part’s passive thermal dissipation. Please attach a picture of the solution PCB itself, front and back. If you would like more guidance on the PCB design, please look at section 11.2 on the LM5146-Q1 datasheet for extra information.

    Thank you,

    Joshua Austria

  • 0 in reply to Joshua Austria
    TI__Intellectual 2660 points

    Hi Joshua,

    Thanks a lot for your reply and suggestions.

    In fact, the customer did a test. When the D1 diode was added to the circuit, the temperature would drop by 20℃, which would be a very noticeable downward trend. So the customer suspects this diode is one of the causes of the chip's temperature being too high. 

    Could you please give some suggestions or comments about it?

    Thank you.

    Regards,

    Ivy

  • 0 in reply to Joshua Austria
    TI__Intellectual 2660 points

    Hi Joshua,

    Could you please help give some comments?

    Thank you.

    Regards,

    Ivy