AN-6982 FAIRCHILD | Alldatasheet
Document overview
- Manufacturer or author: Provided By ALLDATASHEET.COM(FREE DATASHEET DOWNLOAD SITE)
- PDF pages: 15
Technical content
efficiency, but can be also easily disabled using EN pin. voltage brownout protection. converter is controlled by the RDY pin. Figure 1. Typical FAN6982 Application Circuit
output voltage is built to a certain level. required, causing output voltage overshoot. Figure 12. PFC Soft-Start
Table 1. Design Specifications Figure 13. Reference Circuit for Design Example
cycle of 99~98% is obtained. Figure 14. Line-Sensing Circuits
2 RMS
VRMS, it is typical to set the poles around 10~20Hz. are 1.05V (VRMS-UVL) and 1.9V (V RMS-UVH), respectively. as RRMS1=2MΩ, RRMS2=200kΩ, and RRMS3=36kΩ. Therefore, 6MΩ resistor is selected for RIAC.
2 OUT
Figure 15. Ripple Factor with Different Line Voltages
2 OUT HOLD
allowable minimum PFC output voltage during hold-up time.
© 2010 Fairchild Semiconductor Corporation www.fairchildsemi.com The transfer function of the compensation network is obtained as: 1ˆ 22 ˆ 1 2 COMP VI VZ OUT VP s vf f svs f ππ π (37) where: 2.5 1 ,22 MV VI VZ BOUT VC VC VC VP VC VC Gf f andVC R C f RC ππ π =⋅ = ⋅⋅ ⋅ = ⋅⋅ (38) The procedure to design the feedback loop is as follows: (a) Determine the crossover frequency (f VC) around 1/10~1/5 of the line frequency. Since the control-to- output transfer function of power stage has -20dB/dec slope and -90 o phase at the crossover frequency, as shown in Figure 20 as 0dB; it is necessary to place the zero of the compensation network (f VZ) around the crossover frequency so that 45 ° phase margin is obtained. Then, the capacitor CVC1 is determined as: 1 2 2.5 5( 2 ) MV BOUT MAX VC BOUTBOUT VC GI KC VCf π where G MV is the gain of the transconductance error amplifier for the output voltage regulation. To place the compensation zero at the crossover frequency, the compensation resistor is obtained as: VC VC VC R fCπ= ⋅⋅ (40) (b) Place compensator high-frequency pole (f VP) at least a decade higher than f C t o e n s u r e t h a t i t d o e s n o t interfere with the phase margin of the voltage regulation loop at its crossover frequency. It should also be sufficiently lower than the switching frequency of the converter so noise can be effectively attenuated. Then, the capacitor C VC2 is determined as: VC VP VC C fRπ= ⋅⋅ (41) (Design Example) Setting the crossover frequency as 22Hz: 1 2 6 2 2.5 5( 2 ) 70 10 0.9 1.27 2.5 2010 3875 270 (2 22) MV BOUT MAX VC BOUTBOUT VC GI KC VCf nF π π 11 3622 22 2 2 0 1 0 VC VC VC Setting the pole of the compensator at 120Hz: 2 3 11 3.72 21 2 0 3 6 2 1 0 VC VP VC
© 2010 Fairchild Semiconductor Corporation www.fairchildsemi.com 1. Design Summary Application Output Power Input Voltage Output Voltage / Output Current PFC Power Supply 350W 85~264V AC 387V/0.9A
Features
Switch-charge technique of gain modulator provides better PF and lower THD Over-Voltage Protection (OVP), Under-Voltage (UVP), Open-Loop (OLP), and maximum current limit Protections Range function improves system efficiency at low AC line voltage and light load condition Ready pin function provides power-on sequence for the downstream converter Figure 21. Final Schematic of Design Example
© 2010 Fairchild Semiconductor Corporation www.fairchildsemi.com Appendix A MOSFET and Diode Reference Specification PFC MOSFETs Voltage Rating Part Number 500V FQP13N50C, FQPF13N50C, FDP18N50, FDPF18N50, FDA18N50, FDP20N50(T), FDPF20N50(T) 600V FCP11N60, FCPF11N60, FCP16N60, FCPF16N6 0, FCP20N60S, FCPF20N60S, FCA20N60S, FCP20N60, FCPF20N60 Boost Diodes 600V FFP08H60S, FFPF10H60S, FFP08S60S, FPF08S60SN, BYC10600
© 2010 Fairchild Semiconductor Corporation www.fairchildsemi.com References FAN6982 — CCM Power Factor Correction Controller AN-8027 — FAN480X PFC+PWM Combo Controller Application AN-6004 — 500W Power Factor Corrected (PFC) Design with FAN4810 AN-6032 — FAN4800 Combo Controller Applications AN-42009 — ML4824 Combo Controller Applications ATX 350W Evaluation Board of FAN6982+FSBH0F70A DISCLAIMER FAIRCHILD SEMICONDUCTOR RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION, OR DESIGN. FAIRCHILD DOES NOT ASSUME ANY LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCT OR CIRCUIT DESCRIBED HEREIN; NEITHER DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS. LIFE SUPPORT POLICY FAIRCHILD’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, or (c) whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in significant injury to the user. 2. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness.