数据搜索系统,热门电子元器件搜索 |
|
FAN480X 数据表(PDF) 8 Page - Fairchild Semiconductor |
|
FAN480X 数据表(HTML) 8 Page - Fairchild Semiconductor |
8 / 17 page AN-8027 © 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com Rev. 1.0.0 • 8/26/09 8 , (1 cos(4 )) D AVG BOUT LINE I If t π =− ⋅ ⋅ BOUT I , 2 BOUT BOUT RIPPLE LINE BOUT I V fC π = BOUT V , DAVG I D I Figure 14. PFC Output Voltage Ripple (Design Example) With the ripple specification of 12VPP, the capacitor should be: , 0.9 239 22 50 12 BOUT BOUT LINE BOUT RIPPLE I CF fV μ ππ >= = ⋅⋅ ⋅ ⋅ Since minimum allowable output voltage during one cycle line (20ms) drop-outs is 310V, the capacitor should be: 3 22 2 2 , 2 349 20 10 260 387 310 BOUT HOLD BOUT OUT OUT MIN Pt CF VV μ − ⋅ ⋅⋅ × >= = −− Thus, 270 μF capacitor is selected for the PFC output capacitor. [STEP-6] PFC Output Sensing Circuit To improve system efficiency at low line and light load condition, FAN480X provides two-level PFC output voltage. As shown in Figure 15, FAN480X monitors VEA and VRMS voltages to adjust the PFC output voltage. The PFC output voltage when 20µA is enabled is given as: 2 2 20 (1 ) 2.5 FB BOUT BOUT μAR VV - × =× (25) It is typical second boost output voltage as 340V~300V. Figure 15. Two-Level PFC Output Block The voltage divider network for the PFC output voltage sensing should be designed such that FBPFC voltage is 2.5V at nominal PFC output voltage: 2 12 2.5 FB BOUT FB FB R VV RR ×= + (26) (Design Example) Assuming the second level of PFC output voltage is 347V: 2 2 6 6 2.5 (1 ) 20 10 347 2.5 (1 ) 12.9 387 20 10 BOUT FB BOUT V R V k − − =− ⋅ × = −⋅ = Ω × 13k Ω is selected for RFB2. 12 3 (1) 2.5 387 (1) 13 10 1999 2.5 BOUT FB FB V RR k =− ⋅ = −⋅ × = Ω 2M Ω is selected for RFB1. [STEP-7] PFC Current-Sensing Circuit Design Figure 16 shows the PFC compensation circuits. The first step in compensation network design is to select the current- sensing resistor of PFC converter considering the control window of voltage loop. Since line feed-forward is used in FAN480X, the output power is proportional to the voltage control error amplifier voltage as: 0.6 () 0.6 MAX EA BOUT EA BOUT SAT EA V PV P V − =⋅ − (27) where VEA SAT is 5.6V and the maximum power limit of PFC is: 2 . 1 MAX MAX LINE BO M BOUT IAC CS VG R P RR ⋅ ⋅ = (28) |
类似零件编号 - FAN480X |
|
类似说明 - FAN480X |
|
|
链接网址 |
隐私政策 |
ALLDATASHEETCN.COM |
ALLDATASHEET是否为您带来帮助? [ DONATE ] |
关于 Alldatasheet | 广告服务 | 联系我们 | 隐私政策 | 链接交换 | 制造商名单 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 |