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UCC28911: How to disable UCC28911

Part Number: UCC28911

Customer used UCC28911 for the aux power for the AC-DC PSU. Now they were required to shut down UCC28911 if there was external power supply at the output. Thus, they needed to find a way to disable UCC28911 when required, like MCU to control the on or off for the aux power. Could you please help share whether there are any external circuits to disable it? Thank you. 

  • Hello,

    The only way to disable the UCC28911 is to remove power from the device.

    I have always recommended using a series pass regulator using a NPN transistor and a resistor divider from the aux winding output to VDD.  You set the nominal voltage to 13V with a resistor divider and this would put VDD at around 12.4V under nominal operation.  You would then tie a logic level FET to disable the bias supply to VDD.  You just need to pull the base of the NPN to ground so the UCC28911 enters under voltage lockout.