Part Number : M51977FP
Function :Switching regulator control
Manufacturer : MITSUBISHI ELECTRIC
Pinout : 
Description
Mitsubishi IC type M51977P, FP are the off-line primary PWM controller which are especially designed for SMPS to get the regulated DC voltage from AC power supply.
Datasheet PDF Download
Other datasheets in the file : M51977FP, M51977P