Function : Power Supply Supervisor + Regulator + PWM
Package : DIP 20 Pin
Manufacturers : Fairchild
1. half-bridge (or 494) power supply monitoring IC + two 431+ PWM 2. High level of integration and few external components 3. 3.3V, 5V and 12V overvoltage protection 4. 3.3V, 5V and 12V voltage protection 5. -12V and / or -5V voltage protection 6. Over Power and Short-Circuit Protection 7. AC input voltage drops alarm circuit 8. PG circuit 9. PSON and PG signal delay time 10. Remote on / off function 11. containing the error amplifier and oscillator 12. Two 431 regulators for 3.3 and 5V voltage 13. Latch pulse width modulation (PWM), can cycle by cycle switch 14. push-pull pulse width modulation works and totem pole output driver 15. Soft start and maximum duty cycle of 93%
The IC is specially designed for switching power supply system. It provides over-voltage protection, over-current protection, under-voltage protection, on/off control and power good signal generating. OVP/UVP (Over/Under-Voltage Protection) monitors 3.3V, 5V and double 12V to protect our power supply and PC, FPO goes to high when one of these supply voltages exceeds their normal operation voltage range.
The power supply is turned on after 38mS de-bounce time when PSON signal is set from high to low. To turn off power supply, PSON signal is set from low to high and the de-bounce time is 115mS. When PGI input voltage level is lower than the internal 1.15V reference voltage, after 73uS de-bounce time, the PGO signal is pulled low.