UC2854B: GATE PULSE IS NOT COMING ON APPLYING VCC OF +15V.

Hi Navneet, I will get back to you soon. Thanks. ——Teng

Hi Teng,

Please help to share your comments at the earliest.

Hi Navneet,

1, The threshold for PKLMT is 0.0 V. Connect this input to the negative voltage on the current sense resistor. Use a resistor to REF to offset the negative current sense signal up to GND.  However, In your circuit, PKLMT is connected to GND.  Please refer to attached file.

UC3854A and UC3854B Advanced Power Factor Correction Control ICs.pdf

2, MOUT pin is Multiplier output and current sense plus, why connects it  to GND directly?

3, IAC pin is the only multiplier input that should be used for sensing instantaneous line voltage. 

Please check the voltage of ENA pin, VCC pin and REF pin with below requirements.

1, A nominal voltage above 2.65 V on this pin allows the device to begin operating. Once operating, the device shuts off if this pin goes below 2.15 V nominal.  At start-up, Enable Pin should be larger than 2.8V.

2, And VCC turn-on threshold voltage of UCC2854A is 11.2V.

3, The VREF GOOD comparator assures that the MOSFET driver output remains low if the supply of the 7.5 V reference are not yet up.  

Regards,

Teng