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TPD6S300A: Question about RPD_G1 and RPD_G2 pins.

GW
Intellectual 2370 points
Part Number: TPD6S300A
Other Parts Discussed in Thread: BQ25798, , TPS25751, TPD6S300

Tool/software:

Hi, Team

My customer use TPS25751D+BQ25798+TPD6S300A in one of their design.

TPD6S300A  mention that if RPD_G1/RPD_G2  short to GND, it means it support "dead battery resistors". 

I think in TPD6S300A  , the "dead battery resistors" you're talking about are the 5.1K ohm Rd CC resistors. The TPS25751D chip already has a "dead battery mode." When it's in this mode, the TPS25751D will put a 5.1K resistor to ground on the CC pins.

So, since the TPS25751D already does this, do I still need to connect RPD_G1/RPD_G2 of the TPD6S300A to C_CC1/C_CC2? Or should I connect RPD_G1/RPD_G2 to GND (ground)?

I'm worried that if I connect RPD_G1/RPD_G2 to C_CC1/C_CC2, then in dead battery mode, there will be two 5.1K resistors pulling down to ground: one from the TPS25751D and one from the TPD6S300A. Will this cause a problem?

In this situation, should I connect RPD_G1/RPD_G2 to C_CC1/C_CC2, or should I connect RPD_G1/RPD_G2 to GND?

Thanks.

G.W

  • +1
    TI__Mastermind 37855 points

    Hi George,

    GW said:
    TPD6S300A  mention that if RPD_G1/RPD_G2  short to GND, it means it support "dead battery resistors". 

    Incorrect, when you short the RPD pins to GND, you are disabling the dead battery resistors. To use the dead battery resistors and "enable" them, they need to be connected to the CC lines.

    GW said:
    I think in TPD6S300A  , the "dead battery resistors" you're talking about are the 5.1K ohm Rd CC resistors. The TPS25751D chip already has a "dead battery mode." When it's in this mode, the TPS25751D will put a 5.1K resistor to ground on the CC pins.

    Correct, the TPS25751 also has dead battery resistors on the CC lines.

    GW said:
    So, since the TPS25751D already does this, do I still need to connect RPD_G1/RPD_G2 of the TPD6S300A to C_CC1/C_CC2? Or should I connect RPD_G1/RPD_G2 to GND (ground)?

    If the CC lines are being protected by the TPD6S300 and you want the port to support dead battery, RPD_G1/RPD_G2 should be connected to C_CC1/C_CC2.

    GW said:

    I'm worried that if I connect RPD_G1/RPD_G2 to C_CC1/C_CC2, then in dead battery mode, there will be two 5.1K resistors pulling down to ground: one from the TPS25751D and one from the TPD6S300A. Will this cause a problem?

    In this situation, should I connect RPD_G1/RPD_G2 to C_CC1/C_CC2, or should I connect RPD_G1/RPD_G2 to GND?

    The TPS6S300 is designed with this in mind. Because it would hide the TPS25751 RD resistors when the TPD6S300 is not powered, the RPD pins need to be connected so the port will look like a dead battery sink. When the TPD device is powered, it will remove it's RPD resistors and allow the TPS25751 RD resistors to take over.

    Thanks and Regards,

    Chris