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| 型号： | FAN7930BM |
| 厂商： | Fairchild Semiconductor |
| 文件页数： | 14/22页 |
| 文件大小： | 1849K |
| 描述： | IC PFC CTLR CRITICAL CONF 8-SOIC |
| 标准包装： | 95 |
| 模式： | 临界传导（CRM） |
| 频率 - 开关： | 250kHz ~ 350kHz |
| 电流 - 启动： | 120µA |
| 电源电压： | 13 V ~ 20 V |
| 工作温度： | -40°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 供应商设备封装： | 8-SOP |
| 包装： | 管件 |
?2010 Fairchild Semiconductor Corporation
www.fairchildsemi.com
FAN7930B " Rev. 1.0.3
14
The roles of PFC controller are regulating output voltage
and input current shaping to increase power factor. Duty
control based on the output voltage should be fast
enough to compensate output voltage dip or overshoot.
For the power factor, however, the control loop must not
react to the fluctuating AC input voltage. These two
requirements conflict; therefore, when designing a
feedback loop, the feedback loop should be least ten
times slower than AC line frequency. That slow
response is made by C1 at the compensator. R1 makes
gain boost around operation region and C2 attenuates
gain at higher frequency. Boost gain by R1 helps raise
the response time and improves phase margin.
Freq.
C
1
R
1
Proportional
Gain
C
2
Integrator
High-Frequency
Noise Filter
Gain
Figure 33. Compensators Gain Curve
For the transconductance error amplifier side, gain
changes based on differential input. When the error is
large, gain is large to suppress the output dip or peak
quickly. When the error is small, low gain is used to
improve power factor performance.
I
CO M P
Po w e rin g
B ra k in g
m
h
o
5
0
m
h
o
1
5
Figure 34. Gain Characteristic
7. Soft-Start: When V
CC
reaches V
START
, the internal
reference voltage is increased like a stair step for 5 ms.
As a result, V
COMP
is also raised gradually and MOSFET
turn-on time increases smoothly. This reduces voltage
and current stress on the power switch during startup.
V R E F
S S
g
M
V
IN V = 0 . 4 V
I
S O U R C E
C O M P
V
C O M P
I
S O U R C E
C O M P
R
C O M P
= V
C O M P
t
( V
R E F
S S
- V
I N V
)
g
M
= I
S O U R C E
C O M P
V
R E F
E N D
= 2 . 5 V
5 m s
V
C C
V
S T A R T = 1 2 V
Figure 35. Soft-Start Sequence
8. Startup without Overshoot: Feedback control speed
of PFC is quite slow. Due to the slow response, there is
a gap between output voltage and feedback control.
That is why over-voltage protection (OVP) is critical at
the PFC controller and voltage dip caused by fast load
changes from light to heavy is diminished by a bulk
capacitor. OVP can be triggered during startup phase.
Operation on and off by OVP at startup may cause
audible noise and can increase voltage stress at startup,
which is normally higher than in normal operation. This
operation is improved when soft-start time is very long.
However, too much startup time enlarges the output
voltage building time at light load. FAN7930B has
overshoot protection at startup. During startup, the
feedback loop is controlled by an internal proportional
gain controller and when the output voltage reaches the
rated value, it switches to an external compensator after
a transition time of 30 ms. This internal proportional gain
controller eliminates overshoot at startup and an
external conventional compensator takes over
successfully afterward.
D
e p e n d o n L o a d
V
O U T
C O M
P
S
t a r t u p
O
v e r s h o o t
I n
t e r n
a l C
o
n
t r o
l l e r
t
C
o n v e n t i o n a l C
o n t r o l l e r
O
v e r s h o o t - l e s s S
t a r t u p C
o n t r o l
C
o n t r o l T
r a n s i t i o n
Figure 36. Startup without Overshoot
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相关代理商/技术参数 |
参数描述 |
|---|---|
| FAN7930BMX | 功能描述:功率因数校正 IC Critical Conduction Mode PFC Controller RoHS:否 制造商:Fairchild Semiconductor 开关频率:300 KHz 最大功率耗散: 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-8 封装:Reel |
| FAN7930BMX_G | 制造商:Fairchild Semiconductor Corporation 功能描述:IC PFC CTLR CRITICAL CONF 8-SOIC 制造商:Fairchild Semiconductor Corporation 功能描述:Power Factor Correction - PFC Critical Conduction Mode PFC Controller 制造商:Fairchild Semiconductor Corporation 功能描述:Critical Conduction Mode PFC Controller |
| FAN7930C | 制造商:FAIRCHILD 制造商全称:Fairchild Semiconductor 功能描述:The FAN7930C is an active power factor correction(PFC) controller for boost PFC applications that operate in critical conduction mode(CRM). |
| FAN7930CM | 功能描述:功率因数校正 IC Critical Conduction Mode PFC Controller RoHS:否 制造商:Fairchild Semiconductor 开关频率:300 KHz 最大功率耗散: 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-8 封装:Reel |
| FAN7930CMX | 功能描述:功率因数校正 IC Critical Conduction Mode PFC Controller RoHS:否 制造商:Fairchild Semiconductor 开关频率:300 KHz 最大功率耗散: 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-8 封装:Reel |
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