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TPS2543: About detection method of DCP-BC1.2

Noriaki Fukazawa
Expert 1620 points

Part Number: TPS2543

Hello Expert.

I have a question about how to detect DCP-BC 1.2 in TPS2543.


My customer is using CTL, ILIM_SEL terminal in DCP-auto mode.
However, they don't know how to detect DCP-BC1.2.

On page 18 of the datasheet, there is a description about connection
with the BC1.2 device, but what does the bus switch recognize
that a device conforming to BC 1.2 is connected?


My expectation is not a device problem,
but I believe that my customers do not know about the general BC 1.2 standard handshake.
I want your advice.

Best,Regars.
Nori

  • 0
    Expert 1620 points
    Dear Expert.

    My customers hurry to answer this question.
    I guess everyone is busy, but I will be saved if you get support.

    Best,Regars.
    Nori
  • 0 in reply to Noriaki Fukazawa
    TI__Intellectual 990 points

    Hi Nori-san,

    In general, you may use the D+ and D- pins to determine the BC1.2 status of the connected device. Upon connection, the connected BC1.2 device starts driving D+ and D- should follow D+ (in timing and voltage) as both of these pins should be shorted together per BC1.2 specification definition.

    Below is an example of a general DCP waveform. 

    Thank you,

    Jaime

  • 0 in reply to Jaime C
    Expert 1620 points
    Dear Jaime-san

    Thank you for your support.

    For the method of checking the output waveform of BC1.2, I also recognize the same.

    I will change my question.

    When necessary while setting TPS 2543 to DCP-auto mode BC1.2 compliant device
    what is detected when connecting to BC1.2 TPS2543 recognizes and connects internal circuitry
    It is information as to whether it is switching.
    My customers want to know how they recognize on the connected device side.

    Thank you so much for your support many time.
    Best,Regars.

    Nori
  • 0 in reply to Noriaki Fukazawa
    TI__Intellectual 990 points

    Hi Nori-san,

    The best way to recognize how the TPS2543 is switching is by, again, looking at the D+/D- lines because these are the main lines for communication between the two devices.

    With D+/D-, the connected device will pulse differently upon connection as discussed above.

    In general with BC1.2 devices they will go through a primary detection to differentiate between SDP/CDP/DCP, then if necessary a secondary detection to differentiate between CDP and DCP. This is highlighted in the BC1.2 specification located on the USB website.

    Jaime