1 Reply Latest reply on Sep 10, 2020 9:56 AM by MallikaK_41

    CYPD3177 EZ-PD : Fault pin does not trigger when used with USB-A (5V only) chargers




      We are using the CYPD3177 EZ-PD as a DC barrel replacement, the application is marketed for.

      Our target application requires a 20V, 90W supply (i.e. 20V & 4.5A or greater.)


      We have configured the CYPD3177 using external resistors as follows:

      20V supply, 4.5A or greater.


      VBUS min = Rtop 0R, Rbot open = 20V minimum

      VBUS max = Rtop 0R, Rbot open = 20V maximum.

      Isink_Coarse = Rtop 5k1, Rbot = 10k = 4A.

      Isink_Fine = Rtop 5k1, Rbot = 2k4 = 0.5A


      1. Plug in a USB-C supply with the correct power rating, Fault line is low as expected, 20V is present to the application. Expected Behaviour.

      2, Plug in a USB-C supply with underated current, Fault line is high, No voltage is presented to the application. Expected Behaviour.

      3, Plug in a USB-A 5V supply with USB A-C cable, Fault line is low, 5V is presented to the application!


      The datasheet clearly states:

      "Pin 9 - FAULT - The EZ-PD BCR device pulls this line high if the power adapter cannot supply the required voltage or current "


      I can almost understand if the chip was configured to allow 5V, then it might decide to let 5V though without negotiation.

      But with 20V set as a minimum it should not let any power though without completing power negotiation.

      Is this a know bug?


      We have detected this behaviour during verifiaction and so need a resolution as soon as possible.


      Please advise.