This post explains for the PWM Controller.
The Part Number is SD4841.
The function of this semiconductor is Current Mode PWM Controller.
The package is DIP 8 Pin Type
Manufacturer: Silan Microelectronics
Preview images :
SD4840, SD4841, SD4842, SD4843, SD4844 is a current mode PWM controller
with low standby power and low start current for power switch. In standby mode, the circuit enters burst mode to reduce the standby power dissipation.
The switch frequency is 67KHz with ±2.5 KHz jitter frequency for low EMI. stress on transformer during power on is reduced by the builtin 15ms soft start circuit to avoid the saturation of transformer. […]
1. Lower start-up current (Typ.6μA)
2. Frequency jitter for low EMI
3. Overcurrent protection
4. Overvoltage protection
5. Undervoltage lockout
6. Built-in temperature protection
7. Built-in high voltage MOSFET
8. Auto restart mode
9. Built-in soft start
10. Burst mode operation
1. Switch power
Other data sheets are available within the file:
SD4840P67K65, SD4841P67K65, SD4842P67K65, SD4843P67K65, SD4844P67K65