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参数资料
| 型号： | FL7930CM |
| 厂商： | FAIRCHILD SEMICONDUCTOR CORP |
| 元件分类： | 稳压器 |
| 英文描述： | 0.5 A POWER FACTOR CONTROLLER, 350 kHz SWITCHING FREQ-MAX, PDSO8 |
| 封装： | MS-012AA, SOP-8 |
| 文件页数： | 7/20页 |
| 文件大小： | 1290K |
| 代理商： | FL7930CM |
2011 Fairchild Semiconductor Corporation
www.fairchildsemi.com
FL7930 Rev. 1.0.0
15
FL7930
—
Single-Stage
Flyback
and
Bou
ndary-Mode
PFC
Controller
for
Lighting
Figure 36. Control Circuit
Unlike a conventional voltage-mode PWM controller,
FL7930 turns on the MOSFET at the falling edge of
ZCD signal. On instance is decided by the external
signal and the turn-on time lasts until the error amplifier
output (VCOMP) and sawtooth waveform meet. When
load is heavy, output voltage decreases, scaled output
decreases, COMP voltage increases to compensate low
output, turn-on time lengthens to give more inductor
turn-on time, and increased inductor current raises the
output voltage. This is how PFC negative feedback
controller regulates output.
The maximum of VCOMP is limited to 6.5V, which dictates
the maximum turn-on time, and switching stops when
VCOMP is lower than 1.0V.
s
/
V
155
.
0
Figure 37. Turn-On Time Determination
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 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.
Figure 38. Compensators Gain Curve
For the transconductance error amplifier side, gain
changes based on differential input. When the error is
large, gain is large to force the output dip or peak to
suppress quickly. When the error is small, low gain is
used to improve power factor performance.
mho
250
mho
115
Figure 39. Gain Characteristic
8. Soft-Start
: When VCC reaches VSTART, an internal
reference voltage is increased like a stair step for 5ms.
As a result, VCOMP is also raised gradually and MOSFET
turn-on time increases smoothly. This reduces voltage
and current stress on the power switch during startup.
VREF
SS
gM
VINV=0.4V
ISOURCE
COMP
VCOMP
ISOURCE
COMP
RCOMP=VCOMP
t
(VREF
SS-VINV)gM=ISOURCECOMP
VREF
END=2.5V
FL7930 Rev.00
5ms
VCC
VSTART=12V
Figure 40. Soft-Start Sequence
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相关代理商/技术参数 |
参数描述 |
|---|---|
| FL7930CMX | 功能描述:功率因数校正 IC Single Stage Flyback 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 |
| FL7930CMX_G | 制造商:Fairchild Semiconductor Corporation 功能描述:IC PFC CTLR FLYBACK/BOUND 8SOIC |
| FL793-F8 | 制造商:BACO Controls Inc 功能描述: |
| FL7B5BH | 制造商:未知厂家 制造商全称:未知厂家 功能描述:Ball-Grid-Array Thin Film Low-Pass Filter |
| FL7KM12A | 制造商:未知厂家 制造商全称:未知厂家 功能描述:TRANSISTOR | MOSFET | N-CHANNEL | 600V V(BR)DSS | 7A I(D) | TO-220FN |
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