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Original question:

LM63635-Q1: ICs doesn't always start

LM63635-Q1: Strange behavior

Vsevolod Elantsev4
Intellectual 2165 points
Part Number: LM63635-Q1

Hi team,

I want to start new thread about related question.

The customer already collected dozen of chips which has the following symptoms:

  • Different switching frequency.
  • 50/50 startup
  • Doesn't star at all

Could you please check attached spreadsheet with different tabs from customer.
There are tests of protection diodes inside, scopes and schematics. Please review this.

There are not so much comments, but the customer is ready to have a call to discuss these cases.
Please let me know if you have any concerns or you need more information.

Thank in advance for help.


 LM63625 investigation.xlsx 

  • 0
    TI__Mastermind 29080 points

    Hello Vsevold,

    Allow me to follow up after contacting my colleagues.

  • 0 in reply to Marshall_Beck
    TI__Mastermind 29080 points

    Hello Vsevolod,

    I have reviewed the schematics and my comments are below.

    I would also like to review the layout.

    What are the history on these boards? Are they freshly assembled or have been in the system for some time under use?

    U26

    • Input capacitors should be rated for 50V if car battery
    • Recommended output capacitance is 3 x 22uF 1210

     

    U28

    • L18 is quite large. Recommend to keep L18 lower to ensure ripple is between 10-30%

    U2

    • Input cap DC rating isn’t sufficient for 12V battery
  • 0 in reply to Marshall_Beck
    TI__Intellectual 2165 points

    Hi Marshall,
    here are comments from engineer:

    All 5 faulty boards, which I investigated, had failed production End of Line testing. During EOL test they were powered up with 15V DC from the laboratory PSU.

    LM63625 ICs are used to create DC power system of the board: 15V - 5V - 3.3V
    Initial 15V are highly stabilized and generated by special Power Supply source, installed in vehicle.

    U26

    • Input capacitors should be rated for 50V if car battery  - IC is powered with 5V 
    • Recommended output capacitance is 3 x 22uF 1210

     

    U28

    • L18 is quite large. Recommend to keep L18 lower to ensure ripple is between 10-30%

    U2

    • Input cap DC rating isn’t sufficient for 12V battery  - IC is powered with 5V 
  • 0 in reply to Vsevolod Elantsev4
    TI__Guru 57555 points

    Hello

    I will close this post and continue on TI email.

    Thanks