UCC28740: How to shutdown UCC28740 (flyback )to achive zero power consume

Hi Xiaodong,

ucc28740 can't achieve zero standby power , even you pull down the VDD lower than UVLO voltage , there is a ~250uA start up current try to charge VDD.  while keep the controller at standby operation can achieve a lower power consumption. 

For "zero "standby power , we recommend UCC28730 which can achieve <5mW standby power .

Thanks.

Hello Xiaodong,

Thank you for your interest in the UCC28740 flyback controller.

Unfortunately, the UCC28740 is not designed to be turned Off and On.  Even if you grounded or opened the VDD path, the HV-pin connection to 200V would automatically try to start up. To ensure virtually zero input current, you will need to simultaneously discharge the VDD capacitance and open the HV-pin path to the 200V input.

Regards,
Ulrich