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TPS2546: fast charging mode could not be enabled automatically after powering up

Aki Li
Genius 9755 points
Part Number: TPS2546

My customer was using TPS2546 in their laptop project, and found the fast charging mode could not be enabled automatically after powering up. They found the charging current was limited to 900mA after powering up.  

 

  1. During shut down mode, status : DCP mode

Voltage showed at +V5P0A_C , no voltage at P3V3S;

TPS2546_CTL2_P1 =0, TPS2546_CTL1_P1 =0,  TPS2546_CTL3_P1 was pulled high by SW.

 

  1. After powering up, status: CDP mode

Voltage showed at +V5P0A_C and P3V3S;

TPS2546_CTL2_P1=1, TPS2546_CTL1_P1 =1, TPS2546_CTL3_P1 was pulled high by SW.

 

Could you please help check the possible reason for this phenomenon? Thank you.

  • 0
    TI__Genius 9630 points

    Hello,

    What is their ILIM_SEL pin set at? If ILIM_SEL is low, then the charging mode will be SDP which will have a max charging current of 900mA.

    Thanks,

    Emma

  • 0 in reply to Emma Hoying
    TI__Genius 9755 points

    Hi Emma,

    ILIM_SEL is always set high in their design, and it is pulled up to +V5P0A_C through 100kohm resistor.

    The issue was urgent, and we do need your further support there.

  • 0 in reply to Emma Hoying
    TI__Genius 9755 points

    Hi Emma,

    The fast charging worked if starting the test after the laptop power up. During the laptop off, the fast charging worked also, but when powering up the laptop from the off state, the fast charging failed. 

    Customer found this issue now after their product mass production, so it is urgent to fix it, which do need your support here.

  • 0 in reply to Aki Li
    TI__Genius 9630 points

    Hi Aki,

    I think that this is an issue with the CTL or ILIM pins. Can you capture CTL1, 2, 3 and ILIM_SEL in the pass and fail case for me? That is what changes the current limiting. ILIM_SEL may also be not coming up right away which could be putting the charge current limited to SDP.  The more scope captures you can provide of the fail the faster I can help debug this issue and we can understand what is causing this issue.

    Thanks,

    Emma