 |
Motor de Búsqueda de Datasheet de Componentes Electrónicos |
|
|
Motor de Búsqueda de Datasheet de Componentes Electrónicos |
|
FFP08H60S Datasheet(PDF) 9 Page - Fairchild Semiconductor |
|
||||||||||||||||||||||||||||||
FFP08H60S Datasheet(HTML) 9 Page - Fairchild Semiconductor |
|
|
9 / 17 page  AN-8027 © 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com Rev. 1.0.0 • 8/26/09 9 It is typical to set the maximum power limit of PFC stage around 1.2~1.5 of its nominal power such that the VEA is around 4~4.5V at nominal output power. By adjusting the current-sensing resistor for PFC stage, the maximum power limit of PFC stage can be programmed. To filter out the current ripple of switching frequency, an RC filter is typically used for ISENSE pin. RLF1 should not be larger than 100Ω and the cut-off frequency of filter should be 1/2~1/6 of the switching frequency. Diodes D1 and D2 are required to prevent over-voltage on ISENSE pin due to the inrush current that might damage the IC. A fast recovery diode or ultra fast recovery diode is recommended. Figure 16. Gain Modulation Block (Design Example) Setting the maximum power limit of PFC stage as 450W, the current sensing resistor is obtained as: 2 23 . 1 6 72 9 5.7 10 0.098 610 450 MAX LINE BO M CS MAX IAC BOUT VG R R RP ⋅⋅ ⋅⋅ × == = Ω ×⋅ Thus, 0.1 Ω resistor is selected. [STEP-8] PFC Current Loop Design The transfer function from duty cycle to the inductor current of boost power stage is given as: = ) ) BOUT L BOOST V i sL d (29) The transfer function from the output of the current control error amplifier to the inductor current-sensing voltage is obtained as: 11 ⋅ = ⋅ ) ) CS CS BOUT IEA RAMP BOOST vR V vV sL (30) where VRAMP is the peak to peak voltage of ramp signal for current control PWM comparator, which is 2.55V. The transfer function of the compensation circuit is given as: 1 1 2 2 1 2 IC IEA II CS IP s f vf s vs f π π π + =⋅ + ) ) (31) where: 11 2 1 , 22 1 2 MI II IZ IC IC IC IP IC IC G f fand CR C f RC ππ π == ⋅⋅ ⋅ = ⋅⋅ (32) The procedure to design the feedback loop is as follows: (a) Determine the crossover frequency (fIC) around 1/10~1/6 of the switching frequency. Then calculate the gain of the transfer function of Equation (30) at crossover frequency as: 11 @ 2 IC CS CS BOUT IEA RAMP IC BOOST ff vR V vV f L π = ⋅ = ⋅⋅ ) ) (33) (b) Calculate RIC that makes the closed loop gain unity at crossover frequency: 1 @ 1 IC IC CS MI IEA ff R v G v = = ⋅ ) ) (34) (c) Since the control-to-output transfer function of power stage has -20dB/dec slope and -90o phase at the crossover frequency is 0dB, as shown in Figure 17; it is necessary to place the zero of the compensation network (fIZ) around 1/3 of the crossover frequency so that more than 45 ° phase margin is obtained. Then the capacitor CIC1 is determined as: 1 1 2/ 3 IC IC C C Rf π = ⋅ (35) (d) Place compensator high-frequency pole (fCP) at least a decade higher than fIC to ensure that it does not interfere with the phase margin of the current loop at its crossover frequency. 2 1 2 IC IP IC C fR π = ⋅⋅ (36) |
Número de pieza similar - FFP08H60S |
|
Descripción similar - FFP08H60S |
|
|
|
Enlace URL |
| Política de Privacidad |
| ALLDATASHEET.ES |
| ¿ALLDATASHEET es útil para Ud.? [ DONATE ] |
Todo acerca de Alldatasheet | Publicidad | Contáctenos | Política de Privacidad | Intercambio de Enlaces | Lista de Fabricantes All Rights Reserved©Alldatasheet.com |
| Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
|
Family Site : ic2ic.com |
icmetro.com |
Spanish ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
