1 Reply Latest reply on Jun 22, 2020 1:50 AM by PranavaY_81

    CY4533 - Newby INSK current question



      Please forgive this question in case it seems oblivious but I’m new to this sort of tech.


      I’m trying to use a CY4533 evaluation kit to get 12v out of a USB C power and I’m wondering what the 900 ma ISNK current parameter actually means ?

      Is it the maximum current that the device can deliver or is it the trigger current required by the load to trigger the negotiation for the power to be delivered ?


      My plan Is to power a 12 volt Linear activator, ( that draws around 1.5 to 2 amps )  built into a costume from the CY4533.

      With a load connected and the 4533 set to output 5v the motor drives.

      Without a load and the rotary switch set to any other voltage, I can measure the desired voltage on the output terminal.

      However when I connect up my load/linear activator( dc motor) the unit delivers the voltage for a split second before the fault light coming on & then the unit rests and then repeats spitting out the voltage before faulting and resetting.


      I’m hoping that by changing the ISNK resistors that I can’t get things to work as I expected.


      thanks in Advance



        • 1. Re: CY4533 - Newby INSK current question

          Hi Richard,

          The parameter ISNK is the maximum current that the BCR negotiates with the Type-C power source (Power Adapter), Therefore it is the maximum current that can be drawn from the Type-C power source. It is used to form Sink PDO as per USB PD specification. Note that the sink can draw any amount of current less than or equal to the ISNK value.


          Fault LED is turned on in BCR when there mismatch in capabilities on Source and Sink.  Make sure that the Power Adapter (Source) is capable of providing the voltage and current specified.

          To set the ISNK value refer to Table 2-3 and Table 2-4 in BCR EVK Kit Guide and set R10, R12, R13 and R4 value respectively.


          Make sure that the PDO chosen by BCR is also supported by the Power Adapter.