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WL1831MOD: Power sequence of WL1831MOD

Nobuyoshi Arai44
Expert 2575 points
Part Number: WL1831MOD
Other Parts Discussed in Thread: TPS63020

Hello TI Experts,

 

Our customer is facing the problem that the WL1831MOD might be broken on their custom board.

It has worked without any problem in their previous prototyping board. But this problem is happening in their new boards.

The difference between these two boards is that they use the DCDC converter, TPS63020 for VBAT or WL1831MOD.

 

I asked them to check the working of this DCDC. As a result, it seems that the falling edge of DCDC (VBAT) is too slow.

It takes about 1 second that VBAT gets down from 3.7V to 0V. So, if they turn on/off with a short period before the VBAT is not going down to 0V, is there any possibility that WL1831MOD is broken?

 

It would be helpful if you can give any advice.

 

Best Regards,

Nobu Arai

  • 0
    TI__Mastermind 35795 points
    Hi ,
    Can you please elaborate on the issue . When you use TPS63020 for VBAT , does WL18xxMOD never power up or does it not power up reliably when you turn VBAT off/on ?

    Thanks
    Saurabh
  • 0 in reply to S
    Expert 2575 points

    Hello Saurabh-san,

     

    Thank you for the comment.

     

    When WL1831MOD powers up, VIN/VBAT turns on normally. But when WL1831MOD powers down, it looks VBAT is falling down very slowly (about 1 second).

    They do not know the reason why the VBAT is turning off so slow. But they just want to know whether there is a possibility that WL183xMOD is broken or not, when some voltage is existing before VBAT/Vin are turned on. Please see the attached file of the waveform.

     

    Thank you for your comment.

     

    Best Regards,

    Nobu Arai

  • 0 in reply to Nobuyoshi Arai44
    Expert 2575 points

    Hello TI Experts,

    It would be helpful if anyone can give any comment to this question.

    Thank you very much for your help.

    Best Regards,

    Nobu Arai

  • 0 in reply to Nobuyoshi Arai44
    TI__Genius 12260 points
    Hi Nobu,

    From the sequence, I cannot say for sure if Wilink is broken or not. Note that following the power up and power down sequences are critical for not damaging the part. If these are not met, then there is a potential that you will damage the device.

    A few things to try:

    1) Can you use an external VBAT and VIO to control it in a manner similar to your original board?
    2) Are there any other large capacitors on the VDD line that can avoid the fast shut down?
    3) can you go to a different regulator, one that is the same as your original design
    4) try swapping out the part and see if it fixes the issue.


    Hope this helps.

    Thanks,
    Riz
  • 0 in reply to Rizwan Murji
    Expert 2575 points

    Hello Riz-san,

    Thank you for the answer.

    I understand that  you cannot say for sure. 

    We are asking the customer to check your advices and the working of DCDC converter. If we get any inforamtion from them, I will update.

    Best Regards,

    Nobu Arai