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TPS2549-Q1: To use TPS2549-Q1 just like TPS2546-Q1

Koji Hayashi92
Mastermind 6970 points
Part Number: TPS2549-Q1
Other Parts Discussed in Thread: TPS2546-Q1

Hi TI-team

My customer wants to use TPS2549-Q1 just like TPS2546-Q1.

This is because we want to minimize changes to the board and product specifications.

・Recommendation seems to be OPEN, but is it OK to connect the CS pin to GND ?

・If 2.4A product is connected when 2.3A limit is set, will it be 2.1A due to negotiation ?

If you need a schematic, I can show it, but I can't upload it to this forum.

Best Regards,

Koji Hayashi

  • 0
    TI__Expert 8420 points

    Hi,

    IF you don't use the CS pin , pls. let it floats.

    If you set the current limit threshold is lower then the actually charging current , the TPS2549-Q1 will limit the current , it may let the VBUS drop to zero and cycling. 

    Generally we set 20% higher than the actual charging current. 

  • 0 in reply to Michael Tan
    Mastermind 6970 points

    Hi Michael-san

    Thank you for response.

    Why shouldn't I connect the CS pin to GND ? What problem do you have ?
    >・If 2.4A product is connected when 2.3A limit is set, will it be 2.1A due to negotiation ?
    I will describe the above in detail.
    TP2546-Q1 is D+=2.7V, D-=2.0V when Divider2, so I think it is possible to load up to 2.1A.
    TP2549-Q1 is D+=2.7V, D-=2.7V when Divider3, so I think it is possible to load up to 2.4A.
    They don't want to change the product specifications, so they want to use Divider 2.
    They want to set TPS2549-Q1 not to be Divider3.
    Is it possible ?
     
    Best Regards.
    Koji Hayashi
  • 0 in reply to Koji Hayashi92
    TI__Expert 8420 points

    Hi Koji-san,

    The CS pin inside will have some current source inside , it better to let it floats. 

    The TPS2549-Q1 DCP mode is fix at divider 3.  It means it will support 2.4A. It is silicon fixed we can't set some place to change back to divider 3 .