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TUSB211A: How does device react to USB DCP

Matt Mottier
Prodigy 230 points

Part Number: TUSB211A

Tool/software:

For the TUSB211A, if a DCP charger is connected, which shorts D+/D- with less than 200 ohms, how do CD and ENA_HS report?

My hope is that is reports as CD=LOW and ENA_HS=LOW, but I would like verification, if possible.

Matt

  • 0
    TI__Mastermind 48620 points

    Hi Matt,

    The TUSB211A enables the CD pin when it sees either a USB connection with a pull-up resistor on DP or DM, and the ENA_HS pin when it sees a successful High-speed handshake. If with a DCP charger there is a pull-up on either of these lanes or the DCP charger has to enter HS to function, then these pins would read high. Otherwise, these pins should stay low. Personally, I don't have any experience with testing with this kind of setup, so I can't say for sure. I can see if someone on the team would have an idea of what to expect.

    Thanks,

    Ryan

  • 0 in reply to Ryan Kitto
    Prodigy 230 points

    Ryan,

    Thanks for your response.  Typically, the DCP charger has D+ shorted to D- with a 200 Ohm or less resistor.  There is no pull-up on either D+ or D- externally in the charger.  My guess is that the TUSB211A would have CD and ENA_HS low in thise case, but that is just a guess or hope.

    If any of the development boards existed, I could test this out, but I have found none to buy.  The pico version doesn't bring out the CD pin, so it would be harder to test.  I am looking to obtain a part to dead bug, but that won't be immediately.

    Is there anyone in your team that has the development board they could plug in a standfard Type-A charger brick into to see what CD and ENA_HS do?

    Thanks,

    Matt

  • +1 in reply to Matt Mottier
    TI__Mastermind 48620 points

    Hi Matt,

    Matt Mottier said:
    Typically, the DCP charger has D+ shorted to D- with a 200 Ohm or less resistor.  There is no pull-up on either D+ or D- externally in the charger.  My guess is that the TUSB211A would have CD and ENA_HS low in thise case, but that is just a guess or hope.

    If this is the case then it sounds like there wouldn't be any USB data transfer or communication going on, just a dedicated charging port, in which case yes, the CD and ENA_HS pins should be low.

    Matt Mottier said:
    Is there anyone in your team that has the development board they could plug in a standfard Type-A charger brick into to see what CD and ENA_HS do?

    I tested this out in our lab with a USB-A Charging Brick plugged into an outlet > EVM > IPhone, and saw charging on the iphone but no signs of activity on the CD or ENA_HS pin, so I believe the assumption is correct.

    Matt Mottier said:
    If any of the development boards existed, I could test this out, but I have found none to buy.  The pico version doesn't bring out the CD pin, so it would be harder to test.  I am looking to obtain a part to dead bug, but that won't be immediately.

    I would recommend looking at the PICO still. Like you said, it doesnt break out the CD Pin, but there is an LED attached to the ENA_HS pin. If the ENA_HS pin/LED is not high, then that indicates that the redriver is not active. Regardless of whether the CD pin is high or not, if there ENA_HS pin is not high, the redriver will not enable.

    Please let me know if you have any other questions, or maybe want some help getting an EVM going.

    Thanks,

    Ryan

  • 0 in reply to Ryan Kitto
    Prodigy 230 points

    Ryan,


    Thanks again for doing that test.  I will go ahead and purchase the PICO as a check.  I might be able to touch the CD pin during the test.  

    I consider this resolved.

    Matt