收藏本站
Active PFC functions include:
? Active wave shaping of the input current
? Filtering of the high frequency switching
? Feedback sensing of the source current for waveform control
? Feedback control to regulate output voltage
Buck, boost, flyback and other converter topologies are used in active
PFC circuits.
The DC-DC converter input capacitor also benefits from active PFC.
The capacitor can be sized to filter the high frequency ripple of the
active PFC circuit instead of a much larger capacitor that would be
required to smooth the 50-60Hz input. The regulated input of the DC-
DC converter also demands a lower range of duty cycle from the DC-
DC converter. Other benefits of active PFC include increased “hold-
Inductor Selection
Cooper Bussmann Coiltronics ? PFC inductors are available for use with a
wide variety of PFCs from 100W to 250W. They operate with controllers
from several IC manufacturers to provide PFC supply solutions that utilize
either passive or active PFC applications.
Coiltronics PFC inductors range from 200 μ H to 1.2mH. The standard input
voltage range is 85V to 385V with different core materials such as ferrite,
powder iron and Kool-Mu? to provide significant low core loss. The E-core
and toroidal geometries allow using thicker wire to decrease DC resist-
ance and yield higher current capacity. Many vertical or horizontal through-
hole mounting options are available with an operating temperature range of
–20°C to +105°C.
over-time.” Hold over (brownout protection) benefits from always
starting at the maximum voltage; and because energy in the
capacitor is related to 1 / 2 CV 2 , the capacitor can be much smaller than a
capacitor in a converter without active PFC.
Boost Inductor
PFC
Type
None
Appearance
With input
voltage,
switch or
Weight
None
PF
Value
50~60%
Impact on
Environment
Bad
PFC
Cost
None
AC
F1
L2
C1
L1
C2
C3
PFC
B oost
L ine
M odule
C out
F2
D C /D C
Converter
3 .3V ou t
+
fixed input
voltage
With input
voltage,
Passive switch or
Heaviest
70~80%
Better
Normal
L3
F3
D C /D C
5 V ou t
+
fixed input
voltage
Converter
Without
Active
input voltage
Normal 90~99.9%
Best
Expensive
F i g u r e 3 : PFC Boost - Typical application circuit, 3.3 & 5V, 60W combined output power.
The boost-circuit based PFC topology is the most popular. It is an
economical solution for complying with regulations. The inductance
value is selected based on the desired current ripple in the boost
inductor. The inductance value is expressed as follows.
switch
T a b l e 1 : Comparison of passive and active PFC versus no PFC.
Fuses
AC Input Line Fuse
L=
VpKin (min) * d(max)
fs * Δ i
Product safety standards written by Underwriters Laboratories (UL) and the
International Electrotechnical Commission (IEC) require fuses for primary AC
power protection and secondary protection against any catastrophic failure
where:
? VpKin (min) is the peak minimum input voltage
? fs is the switching frequency
? Δ i is the ripple current
? d(max) is the maximum duty cycle expressed as:
within the input filter capacitors, PFC boost module, output electrolytic
capacitors (Cout) or the DC-DC converters. The PFC boost module usually
does not contain overcurrent protection; if a short-circuit is applied across
its output terminals, there is no internal circuit opening device to safely
interrupt the power. Without fuse protection in the AC input line (see
fuse F1 in Figure 3), the boost converter is not protected.
Fusing the DC-DC converter input lines is essential for protection against a
d(max) =
1- VpKin (min)
Vo
where Vo is the output voltage
catastrophic DC-DC converter failure (see fuses F2 and F3 in Figure 3).
Protecting the DC-DC Converter
Although the primary input line fuse will eventually activate, DC fuses
The rms boost inductor current is expressed as:
positioned right at the input to the DC-DC converters will limit the energy
IL (rms) = in
I    (pk)
2
A
delivered by the hold-up capacitors (Cout) and will prevent failure to the
PFC boost module.
发布紧急采购，3分钟左右您将得到回复。

采购需求

(若只采购一条型号，填写一行即可)

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

*型号 *数量 厂商 批号 封装
添加更多采购

我的联系方式

*
*
*
相关PDF资料
CTZ3E-50C-W1-PF CAP TRIMMER 4.5-50PF 25V SMD
CV31A080 CAP TRIMMER 2-8PF 350V TH
CV31A180 CAP TRIMMER 5.5-18PF 350V TH
CV31B110 CAP TRIMMER 2.5-11PF 350V TH
CV31C250 CAP TRIMMER 8-25PF 350V TH
CV31D350 CAP TRIMMER 9-35PF 200V TH
CV31E600 CAP TRIMMER 15-60PF 200V TH
CV35A090 CAP TRIMMER 2.5-9PF 100V TH
相关代理商/技术参数
CTX16-18484 制造商:TI 制造商全称:Texas Instruments 功能描述:A 0.9-A Constant Current Supply with PFC for 100-W LED
CTX16-18484-R 功能描述:固定电感器 PFC W/AUX WDG 1mH 3.1A PK RoHS:否 制造商:AVX 电感:10 uH 容差:20 % 最大直流电流:1 A 最大直流电阻:0.075 Ohms 工作温度范围:- 40 C to + 85 C 自谐振频率:38 MHz Q 最小值:40 尺寸:4.45 mm W x 6.6 mm L x 2.92 mm H 屏蔽:Shielded 端接类型:SMD/SMT 封装 / 箱体:6.6 mm x 4.45 mm
CTX16-18610-R 功能描述:固定电感器 TRANSFOR HALF BRIDGE 1.8mH EF25 THT RoHS:否 制造商:AVX 电感:10 uH 容差:20 % 最大直流电流:1 A 最大直流电阻:0.075 Ohms 工作温度范围:- 40 C to + 85 C 自谐振频率:38 MHz Q 最小值:40 尺寸:4.45 mm W x 6.6 mm L x 2.92 mm H 屏蔽:Shielded 端接类型:SMD/SMT 封装 / 箱体:6.6 mm x 4.45 mm
CTX16-18625-R 功能描述:固定电感器 BUCK W/AUX WDG700uH @1A PK THT RoHS:否 制造商:AVX 电感:10 uH 容差:20 % 最大直流电流:1 A 最大直流电阻:0.075 Ohms 工作温度范围:- 40 C to + 85 C 自谐振频率:38 MHz Q 最小值:40 尺寸:4.45 mm W x 6.6 mm L x 2.92 mm H 屏蔽:Shielded 端接类型:SMD/SMT 封装 / 箱体:6.6 mm x 4.45 mm
CTX16-18702-R 功能描述:固定电感器 PFC 150uH @7.8A PEAK 2WIRE THT RoHS:否 制造商:AVX 电感:10 uH 容差:20 % 最大直流电流:1 A 最大直流电阻:0.075 Ohms 工作温度范围:- 40 C to + 85 C 自谐振频率:38 MHz Q 最小值:40 尺寸:4.45 mm W x 6.6 mm L x 2.92 mm H 屏蔽:Shielded 端接类型:SMD/SMT 封装 / 箱体:6.6 mm x 4.45 mm
CTX16-18833-R 功能描述:耦合电感 500uH 3A PEAK RoHS:否 制造商:Bourns 电感 - 并联:10 uH 电感 - 串联:40 uH 容差:20 % 最大直流电流:2.08 A 最大直流电阻:0.0826 Ohms 端接类型:SMD/SMT 工作温度范围:- 40 C to + 105 C 系列:SRF0703 类型:Dual-Winding Shielded Power Inductors
CTX17-17640-R 功能描述:固定电感器 IND SHLD DRM 1.45MM .47UH RoHS:否 制造商:AVX 电感:10 uH 容差:20 % 最大直流电流:1 A 最大直流电阻:0.075 Ohms 工作温度范围:- 40 C to + 85 C 自谐振频率:38 MHz Q 最小值:40 尺寸:4.45 mm W x 6.6 mm L x 2.92 mm H 屏蔽:Shielded 端接类型:SMD/SMT 封装 / 箱体:6.6 mm x 4.45 mm
CTX17-18765-R 功能描述:固定电感器 200nH, 100kHz, 2 Phases, SMT RoHS:否 制造商:AVX 电感:10 uH 容差:20 % 最大直流电流:1 A 最大直流电阻:0.075 Ohms 工作温度范围:- 40 C to + 85 C 自谐振频率:38 MHz Q 最小值:40 尺寸:4.45 mm W x 6.6 mm L x 2.92 mm H 屏蔽:Shielded 端接类型:SMD/SMT 封装 / 箱体:6.6 mm x 4.45 mm