FA5534

PFC / PWM Combination IC FA5533/34 Features Features •Critical mode Power Factor Correction and PWM are combined : suitable for smaller power supply •Internal start-up circuit with 500V rating and low frequency operation achieves 340mW input at no load when PFC stops. • Small Output Capacitance : Linearly reduced frequency for light load makes small ripple voltage. • PFC stops below half load ( only for FA5533 ) •Vcc rating 28V allows no series regulator for PW M_ FB LV Block Diagram Block Diagram COMP MUL AC under development under development PFC_ IS ZCD LIG HT_ LOAD ZCD ERR PFC_ FB + MUL R TIME R R 1shot Overvoltag e detection OVP LV OVP S + - R Q RESTART UVLO PFC_ RE G _ OK LIGHT_ LOAD UVLO_ AC PFC_ OUT PFC section UVLO_ AC + UVLO_ AC LIGHT_ LOAD UVLO_ VCC VCC STAR T off + LV - - + PFC_ R E G_ OK VH Common section RE G_ PFC on - AC detect ACD PW M_ RE G_ OK RE G_ PW M on PW M section PW M_ R E G Q VCO OSC FOSC PW M_ DE LAY Dma PW M T Q CLR 1shot T S R Q auxiliary winding to clamp Vcc voltage. •Adjustable Soft Start time •Auto-Restart Over Load Protection •Auto-Restart Over-Voltage Protection for Vcc •Adjustable Start-up sequence for PFC and PWM: easy Full Load Start-up •Brown-Out below 70Vac and 70Vdc of PFC Output •16 pins package ( DIP/SO ) CS VCC PW M OVP slope + RESTART UVLO PW M_ RE G_ OK LV UVLO_ AC PW M_ OUT + - + + + PW M VCC + RESTAR T PW M_ RE G UVLO + LIGHT_ LOAD delay GND + Overload RE START LIGHT_ LOAD PW M_ IS Usage : Notebook PC, LCD Monitor, LCD-TV, Laser Beam Printer etc. PFC / PWM Combination IC FA5533/34 Application Circuit Application Circuit under development under development PFC section P F C s e ct io n PWM s e ct io n P W M section PFC / PWM Combination IC FA5533/34 Timing Chart FA5533 Timing Chart ((FA5533 )) Heavy Load → Light Load → Heavy Load Gate of PPF C FC OUT P MOSFETU T (d ri v e ) AC Line e A C l in voltage v o lt age under development under development Start-up ( Power-ON ) AC Line A C lin e voltage v o lt age Stop ( Power-OFF ) PF PFC ou tpC t u OUTPUTg e vo l t a voltage PW M Gate of PWMU T OUT P (d ri v e MOSFET ) VCC pin Vc c v o lt age voltage Vc VCC pinc v o lt age voltage PF C GateT P U T of OU PFC) (d r iv e MOSFET Gate of PF C OUFC T P TP U (d r iv e MOSFET) PFC PF C out put OUTPUT vo voltageltage 0. 5V PWM O u tput DC vo l t a OUTPUTg e F u ll l o a d PFC PF C OUTPoutput UT v o lt age voltage Heavy Load L ig h t lo a d 70V dc Light Load F u ll l o a d Heavy Load CS pin CS voltage p in 0.5V → PW M Gate of PWM OU T P U T (d r iv e MOSFET ) Gate of PWM PW M MOSFET ) (d r iv e OU T P U T PWMODC u t put v UT OUTPo ltage O u t put PWMvDC o lt age OUTPUT 5m s 5ms