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TPS25751: Detecting the connection of a Type-C AC adapter when AC is not connected

Kesokeso
Prodigy 20 points
Part Number: TPS25751

Tool/software:

We are developing an application that charges a battery from a Type-C port using TPS25751 and a charge IC. In this application, it only works as a sink, not as a source (the Type-C port is charge only).

We need to detect whether the Type-C connector is connected or not. Of course, if a general Type-C AC adapter is connected to the AC side, it is possible to detect the connection by PD negotiation.

However, we found that it is not possible to detect when the Type-C AC adapter is not connected to the AC side. We would like to detect even when the Type-C AC adapter is not connected to the AC side.

What methods are there?

For example, if we prepare a dedicated Type-C AC adapter with a tampered SBU pin, it is possible to detect even when the AC adapter is not connected to the AC side, but we would like to be able to detect even with a general Type-C AC adapter without special tampering.

  • +1
    TI__Mastermind 37855 points

    Hi Kesokeso,

    The TPS25751 probably would not be able to detect an unpowered AC adapter, and the TPS25751 does not have any other function to detect a connection on the port.

    The TPS25751 port detection is based off of voltage sensing on the CC lines.

    A connection is discovered when the source pulls up the CC lines through Rp resistors. Rd resistors to ground on the sink side create resistor divider circuit, biasing a specific voltage on the CC line that indicates a connection.

    If the AC adaptor is not powered, the pullup voltage is likely not asserted and the CC line will never see the connect.

    Kesokeso said:
    What methods are there?

    With the TPS25751, we have not additional methods for plug detection, especially for unpowered plugs.

    Thanks and Regards,

    Chris