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TPS2546: Seeking Clarification on BC1.2 TPS2546 Functionality and Behavior

SHH
Mastermind 32346 points
Part Number: TPS2546
Other Parts Discussed in Thread: TPS25810, TPS25815

Hi Team,

Customer has some questions about BC1.2 TPS2546:

1.customer experimented a bit with EVM, and TPS2546 seems to power off and then re-power after switching CTL. What's the reason for this?

2. When using TPS25810+TPS2546 on a Type-C port, even when the system is shut down, CTL is fixed in CDP mode. What's the reason for this?

3.If a customer is using a standard USB Type-A, is it feasible for TPS2546 to be fixed in CDP mode without switching?

BR,

Scott

  • 0
    TI__Mastermind 33820 points

    Hi Scott,

    I will get back to you regarding these questions by Monday EOB.

    Regards

  • 0 in reply to Tommy Lin
    TI__Mastermind 32346 points

    looking forward to get your response. thanks.

  • 0 in reply to SHH
    TI__Mastermind 33820 points

    Hi Scott,

    Can you provide the ILIM and CTLx setup they are using?

    SHH said:
    TPS2546 seems to power off and then re-power after switching CTL

    Do you mean that the VOUT dropped after changing CTLx config?

    If your customer wants data capability on the Type-A port you will want to keep it in CDP mode. It should not have problem with keeping TPS2546 in CDP mode.

    Regards

  • 0 in reply to Tommy Lin
    TI__Mastermind 32346 points

    Hi Tommy,

    This is a behavior from the "another project" side, and the RD of "this project" is currently assessing whether to follow it, but it hasn't yet been defined to Type-C.

    Do you mean that the VOUT dropped after changing CTLx config?

    >>customer's feedback: I've been conducting experiments using EVM and found that whenever CTL switches, TPS2546 VOUT will always turn off the power and then turn it back on. So, I'm wondering if placing the TPS2546 in the Type-C diagram is intended to avoid this power off and restart state, hence fixing the state in CDP mode?

    Regards

  • 0 in reply to SHH
    TI__Mastermind 33820 points

    Hi Scott,

    OUT discharge is the expected behavior when CTLx config is changed because TPS2546 needs to resample the CTLx to go to the correct charging state.

    SHH said:
    placing the TPS2546 in the Type-C diagram is intended to avoid this power off and restart state, hence fixing the state in CDP mode?

    Can you point me towards this diagram? The diagram I saw in the TPS25810 datasheet is the one below and it only support DCP.

    The purpose of using TPS2546 with other Type-C DFP only controllers (like TPS25810) is because the Type-C DFP only controller don't have BC1.2 support. Fixing the state in CDP mode is to preserve the data capability and the 1.5A charge current while avoiding the OUT discharge when changing mode.

    Regards 

  • 0 in reply to Tommy Lin
    TI__Mastermind 32346 points

    Dear Tommy,

    Here's a brief summary for your understanding, please amend if there are any issues:

    The TPS2546 discharges VOUT and then re-powers it when switching CTL in order to re-sample. In the case of standard Type-C DFP-only controllers, if they need to add BC1.2 TPS2546, since VOUT is connected to the Type-C DFP-only controllers and TPS2546 cannot discharge and re-sample, it is fixed in CDP mode.

    Please also assist with the following two queries:

    1. When the TPS2546 is on a standard USB port, do we decide whether it should be in SDP, CDP, or DCP mode during shutdown? Or is there a regulation by the USB association?
    2. In cases such as the TPS25815 Controller, which includes both Type-C DFP & BC1.2, does its behavior involve discharging the Type-C VOUT when switching CTL?

    Best Regards.

    Scott

  • 0 in reply to SHH
    TI__Mastermind 33820 points

    Hi Scott,

    SHH said:
    The TPS2546 discharges VOUT and then re-powers it when switching CTL in order to re-sample. In the case of standard Type-C DFP-only controllers, if they need to add BC1.2 TPS2546, since VOUT is connected to the Type-C DFP-only controllers and TPS2546 cannot discharge and re-sample, it is fixed in CDP mode.

    Correct.

    SHH said:
    When the TPS2546 is on a standard USB port, do we decide whether it should be in SDP, CDP, or DCP mode during shutdown? Or is there a regulation by the USB association?

    Designer should decide this. To my knowledge there is no regulation on this.

    SHH said:
    In cases such as the TPS25815 Controller, which includes both Type-C DFP & BC1.2, does its behavior involve discharging the Type-C VOUT when switching CTL?

    TPS25815 only samples the CTL pin when a device is attached. If you change the CTL pin when a device is attached the BC1.2 mode will not change.

    Regards