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TPS2514A: Auto-detect mechanism

Robert Ross
Prodigy 20 points
Part Number: TPS2514A
Other Parts Discussed in Thread: TPS2513

This part uses an auto-detect mechanism to select and lock onto a particular DCP profile, like the divider mode or BC1.2, etc. 

This is somewhat documented in section 8.5.3 of the datasheet.  However the explanation about what and how this works is somewhat thin.

Can you help me understand how this auto-detect works, what it is detecting to lock onto a profile, and what it uses to decided to switch to the next profile.

  • 0
    TI__Intellectual 1920 points
    Hi Robert,

    The auto-detect mechanism is a state machine that changes states depending on the D+ and D- lines. Comparators and some logic are used to detect if voltages are in the correct range for the specific mode. If they are not, then the device switches to the next mode until it locks at the correct signature.

    Regards,
    Donovan
  • 0 in reply to Donovan Porter
    Prodigy 20 points
    But as I understand this, the TPS2513 is the device that output the voltages on D+ and D- for the device (cellphone, tablet, etc) to read like BC1.2 or one of the divider modes. I guess you are inferring that the TPS2513 presents a profile by driving the D+ and D- lines with a particular profile, say 2.7V on both lines to indicate Apple 12W. And then the TPS2513 quits driving D+ and D- and reads the lines with the comparators ?
  • 0 in reply to Robert Ross
    TI__Intellectual 1920 points

    Hi Robert,

    The portable device (device connecting to the port like a phone or tablet) initializes the process by putting a signature on the D+ and D- lines (whether it's typical BC1.2 or a divider mode).  The TPS2513 or 14A respond to the signature.  So the TPS2513/14A has to detect what signature is being put on the D+ and D- lines and then respond with the correct signature to let the portable device know it is compatible. This is why there is an auto-detect block within the block diagram. 

    Regards,

    Donovan