AN4107 FAIRCHILD | Alldatasheet

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voltage. The non-inverting input is internally biased at 2.5V . the multiplier and is pinned out for the loop compensation. reducing the input current drawn from the mains(soft OVP). the output stage and the external power switch turned off. goes back into its linear region. output under all line and load conditions. pre-converter load appear to be resistive to the ac line. multiplier output and its inputs. Figure 3. Error Amplifier and OVP Block

connecting it to the zero current detector Pin 5. 500us after the inductor current reached zero. Figure 6. Zero Current Detector Block designed specifically for a direct drive of power MOSFET. required for the reliable circuit operation.

  1. Circuit Components Design

frequency has to be above the audio frequency.

The auxiliary winding voltage is lowest at the highest line. So the number of auxiliary winding can be obtained by (7). suppress the high frequency ringing voltage. input displacement factor(IDF), defined as IDF ≡cosθ . Figure 7. Input Current and Inductor Current Waveform during a Switching Cycle

©2001 Fairchild Semiconductor Corporation Diode average current can be calculated by (21). The total diode loss can be calculated by (22) and then a diode can be selected considering diode thermal characteristic. 3-2. Control circuit design 1) Output voltage sensing resistor and feedback loop design R 1 is determined by the maximum output over voltage, ∆Vovp and R2 is determined by (23). The feedback loop bandwidth must be narrower than 20Hz for the PFC application. Therefore a capacitor is connected between INV and EA_OUT to eliminate the 120Hz ripple voltage by 40dB. The error amp compensation capacitor can be calculated by (24). To improve the power factor, C comp must be increased than the calculated value. And to improve the system response, C comp must be lowered than the calculated value. 2) Zero current detection resistor design Idet current should be less than 3mA, therefore zero current detection resistor is determined by (25). 3) Start-up circuit design To start up the FAN7527, the start-up current must be supplied through a start-up resistor. The resistor value is calculated by (26) and (27). The start-up capacitor must supply IC operating current before the auxiliary winding supplies IC operating current maintaining Vcc voltage higher than the UVLO voltage. Therefore the start up capacitor is designed by (28). 4) Line voltage sense resistor and current sense resistor design The maximum line voltage sensing gain is determined by (29) at the highest line. Calculate the pin 3 voltage at the lowest line using G in(max) by (30). Then the current sense resistor is determined by (31), (32) and (34). Once the current sense resistor is determined, then the minimum line voltage sensing gain, G in(max) is determined by (31). And attach 1nF capacitor in parallel with R2 to reduce the switching ripple voltage. 4. Design Example A 100W converter is designed to illustrate the design proce- dure. The system parameters are as follows.

  • Maximum output power : 100W
  • Input voltage range : 85Vrms~265Vrms
  • Output voltage : 400V
  • AC line frequency : 60Hz
  • PFC efficiency : 90%
  • Minimum switching frequency : 34kHz
  • Input displacement factor(IDF) : 0.98
  • Input capacitor ripple voltage : 24V
  • Output voltage ripple : 8V
  • OVP set voltage : 450V 4-1. Inductor design The boost inductor is determined by (6). Calculate it at both the lowest line and the highest line and choose the lower value. The calculated value is 586uH. To get the calculate inductor value, EI3026 core is used and the primary winding is 62 turns. The air gap is 0.586mm at both legs of the EI core. The auxiliary winding is determined by (7) and the auxiliary winding is 5 turns. 4-2. Input capacitor design The minimum input capacitance is determined by the input voltage ripple specification. The calculated minimum input IDavg IOm a x()=2 1 () PDiode VfIDavg=2 2 () VO 2.5– ∆ VOVP 2.5R1 Ccomp Ridet Naux VO⋅ RST Vin peak_min() Vth st() max– ISTmax PRst in rms_max() RST CST Idcc VPIN3 Vin peak_max() Rin2 Vin peak_max() Gin max() 3.8V<⋅=2 9 () VOm() KV in peak_min() Rin2 Rsemse VOm() IL peak_max() Rin2 2.5⋅ V η Vin peak_min() Rsense 1.8V IL peak_max() η Vin peak_min() PRsense 2 VOIOm a x() η Vin peak_min()  2 Rsense⋅⋅=1 W < 33() Rsense η Vin peak_min() VOIOm a x()  2 ⋅< 34()

capacitor(sum of all capacitors connected to the input). The calculate value is 430Ω and the selected value is 22kΩ . sense resistance is 0.48 Ω and the selected value is 0.2 Ω . The selected value is 2.7MΩ . table 1 shows the 100W demo board components list. Figure 11. Application circuit diagram

©2001 Fairchild Semiconductor Corporation Table 1: 100W demo board part list Part# Value Note Part# Value Note Fuse Capacitor F1 250V/3A - C1 47nF 275Vac Varistor C2 150nF 275Vac V1 471 - C3,C4 2200pF 3000V NTC C5 0.47nF 630V RT1 10D-9 - C6 47nF 35V Resistor C7 0.33nF MLCC R1 2.7M Ω 1/4W C8 100nF 450V R2 18k Ω 1/4W C9 102 Ceramic R3 150k Ω 1W Diode R4 100 Ω 1/4W BD1 660(600V/6A) Bridge Diode R5 22k Ω 1/4W D1 1N4148 - R6 47 Ω 1/4W D2 BYV26E 1000V/1A R7 0.2 Ω 1W Line Filter R8 1.2M Ω 1/4W LF1 45mH - R9 7k Ω 1/4W Inductor R10 500k Ω 1/4W T1 590uH(62T : 5T) EI3026 VR1 103 - MOSFET IC Q1 FQPF6N50 500V/6A IC1 FAN7527 ----

©2001 Fairchild Semiconductor Corporation Table 2: 150W demo board part list Part# Value Note Part# Value Note Fuse Capacitor F1 250V/3A - C1 330nF 275Vac Varistor C2 330nF 275Vac V1 471 - C3,C4 2200pF 3000V NTC C5 0.68nF 630V RT1 10D-9 - C6 47nF 35V Resistor C7 1nF MLCC R1 2.2M Ω 1/4W C8 150nF 450V R2 20k Ω 1/4W C9 102 Ceramic R3 150k Ω 1W Diode R4 100 Ω 1/4W BD1 660(600V/6A) Bridge Diode R5 22k Ω 1/4W D1 1N4148 - R6 47 Ω 1/4W D2 SUF15J 600V/1.5A R7 0.2 Ω 1W Line Filter R8 1.2M Ω 1/4W LF1 45mH - R9 7k Ω 1/4W Inductor R10 500k Ω 1/4W T1 500uH(83T:5T) MPP Core VR1 103 - MOSFET IC Q1 FQA9N50 500V/9A IC1 FAN7527 - - - -

©2001 Fairchild Semiconductor Corporation Table 3: 200W demo board part list Part# Value Note Part# Value Note Fuse Capacitor F1 250V/3A - C1 330nF 275Vac Varistor C2 330nF 275Vac V1 471 - C3,C4 2200pF 3000V NTC C5 0.68nF 630V RT1 10D-9 - C6 47nF 35V Resistor C7 1nF MLCC R1 2.2M Ω 1/4W C8 220nF 450V R2 22k Ω 1/4W C9 102 Ceramic R3 150k Ω 1W Diode R4 100 Ω 1/4W BD1 660(600V/6A) Bridge Diode R5 22k Ω 1/4W D1 1N4148 - R6 47 Ω 1/4W D2 SUF15J 600V/1.5A R7 0.1 Ω 1W Line Filter R8 1.2M Ω 1/4W LF1 45mH - R9 7k Ω 1/4W Inductor R10 500k Ω 1/4W T1 400uH(74T:5T) MPP Core VR1 103 - MOSFET IC Q1 FQA13N50 500V/13A IC1 FAN7527 - - - -

©2001 Fairchild Semiconductor Corporation Nomenclature IL(peak) (t) : inductor current peak value during one switching cycle IL(peak) : inductor current peak value during one AC line cycle IL(peak_max) : maximum inductor current peak value IL (t) : inductor current ID : boost diode current Iin (t) : input current Iin (peak) : input current peak value Iin (peak_max) : maximum of the input current peak value Iin (rms) : input current RMS value IQrms : MOSFET rms current IDrms : diode rms current IDavg : diode average current IO : output current IO (max) : maximum output current Vin (t) : input voltage ∆Vin (max) : maximum input voltage ripple Vin (peak) : input voltage peak value Vin (peak_max) : maximum input voltage peak value Vin (peak_min) : minimum input voltage peak value Vin (rms) : input voltage RMS value Vin (rms_max) : maximum input voltage RMS value Vin (rms_min) : minimum input voltage RMS value Vin (LL) : low line rms input voltage Vin (HL) : high line rms input voltage VO : output voltage ∆VO (max) : maximum output voltage ripple ∆VOVP : maximum output over voltage PO : output power PO(max) : maximum output power Pin : input power η : converter efficiency ton : switch on time toff : switch off time tf : MOSFET current falling time TS : switching period fac : AC line frequency ω : AC line angular frequency fSW : switching frequency fSW(max) : maximum switching frequency fSW(min) : minimum switching frequency L : boost inductance CO : output capacitance Cin : input capacitance η : converter efficiency Naux : auxiliary winding turn number NP : boost inductor turn number Ccomp : compensation capacitance Ridet : zero current detection resistance RST : start up resistance R1 : output voltage divider top resistance R2 : output voltage divider bottom resistance Rin1 : input voltage divider top resistance Rin2 : input voltage divider bottom resistance Rsense : current sense resistance ISTmax : maximum start up supply current CST : start up capacitance HY(ST)min : minimum UVLO hysteresis K : multiplier gain Gin (min) : minimum input voltage sense gain Gin (max) : maximum input voltage sense gain

©2001 Fairchild Semiconductor Corporation

10/11/01 0.0m 002 Stock#ANxxxxxxxxx  2001 Fairchild Semiconductor Corporation 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 CORPROATION. 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. www.fairchildsemi.com