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TPS2544: Keep CDP from S0 to S3

Ann_Lien
Genius 12860 points
Part Number: TPS2544

Hi expert,

My customer has a question on TPS2544 mode changing. They now connect VBUS with another device. VBUS will drop since mode will be changed from S0_CDP to S3_DCP_auto and will effect this device operation .

So they now want to keep CDP mode from S0 to S3. Is that any concern on this case?

P.S. They've already tested with their system(with TPS2544) and keep CDP mode from S0 to S3 to S0. Device will not loss connection and also VBUS will not drop to effect another device.

Best regards,

Ann Lien

  • 0
    TI__Mastermind 29995 points
    Hello Ann,

    I'm a little confused on your question. Are you asking if it is alright to transfer from S0 CDP mode to S3 DCP_auto mode? If that is your question, then yes that is alright and seeing the drop in VBUS is expected.
  • 0 in reply to Adam Mc Gaffin
    Prodigy 10 points
    Hi Adam,

    Thanks for your reply.
    However, we are asking that if we keep CDP mode from S0 to S3 in our computer. We didn't change mode in S0 to S3. Is there any concern about this situation?

    More informations:
    1. Fast charging and data transmitting is ok in S0.
    2. Fast charging is ok in S3.
    3. Both low speed/full speed KB can wake up in S3. (didn't have to wait 60 seconds)
    4. We only demand for 1.5A charging in Andorid/IOS system
    Thanks
  • 0 in reply to Adam Mc Gaffin
    TI__Genius 12860 points

    Hi Adam,

    Thanks for your reply!!

    We don't want to see voltage drop from S0 to S3 so we want to keep S0 and S3 both in CDP mode then VBUS would not drop. So our question is do you have concern if we set CDP for S0 and S3? Such like device will loss connection in certain condition. Thanks!

    Best regards,

    Ann Lien

  • 0 in reply to Ann_Lien
    TI__Mastermind 29995 points

    Hello Ann,

    Thank you for reaching out via phone to try and clarify the issue. So that we have a comprehensive forum conversation for those that may have a similar question, I'm going to post the answer here again.

    The question that Ann was asking is if there any problems if you keep the part in CDP mode, but change the power state from S0 to S3 and vice versa. After our discussion, there are two things that are potentially wrong with this.

    First, based on the datasheet, the part can not be in the S3 power state while also being in CDP mode. This is shown in tables 2 and 3 within the TPS2544 datasheet. In order to be in CDP mode, CTL1, CTL2, CTL3, and ILIM_SEL must all be pulled high to a value of 1. To be in the power state S0 CTL1 must be pulled high, and to be in power state S3, CTL1 must be pulled low. So if you wish to be in CDP mode, you will start off in the S0 power state, but to change to the S3 power state you will have to pull CTL1 low, which will then take you out of the CDP mode and put you into DCP_Auto mode.

    Once that was stated, Ann shared with me that the customer was somehow able to go from the S0 power state to the S3 power state, but stay in CDP mode the entire time. Since neither of us have seen this done before, we decided that it would be best to recommended to not use the part in this manner as there is no data stating that this works and isn't a bug within the system.