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| 型号： | FL7930CM |
| 厂商： | Fairchild Semiconductor |
| 文件页数： | 16/23页 |
| 文件大小： | 0K |
| 描述： | IC PFC CTLR FLYBACK/BOUND 8SOICN |
| 标准包装： | 95 |
| 类型： | 镇流器控制器 |
| 频率： | 250kHz ~ 350kHz |
| 电流 - 电源： | 2.5mA |
| 电源电压： | 13 V ~ 20 V |
| 工作温度： | -40°C ~ 125°C |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 供应商设备封装： | 8-SOP |
| 包装： | 管件 |
9. THD Optimization : Total harmonic distortion (THD)
is the factor that dictates how closely input current
shape matches sinusoidal form. The turn-on time of the
PFC controller is almost constant over one AC line
period due to the extremely low feedback control
response. The turn-off time is determined by the current
decrease slope of the boost inductor made by the input
voltage and output voltage. Once inductor current
To improve this, lengthened turn-on time near the zero
cross region is a well-known technique, though the
method may vary and may be proprietary. FL7930B
optimizes this by sourcing current through the ZCD pin.
Auxiliary winding voltage becomes negative when the
MOSFET turns on and is proportional to input voltage.
The negative clamping circuit of ZCD outputs the
current to maintain the ZCD voltage at a fixed value.
becomes zero, resonance between C OSS and the boost
The sourcing current from the
ZCD is directly
inductor makes oscillating waveforms at the drain pin
and auxiliary winding. By checking the auxiliary winding
voltage through the ZCD pin, the controller can check
the zero current of boost inductor. At the same time, a
minor delay is inserted to determine the valley position
of drain voltage. The input and output voltage difference
is at its maximum at the zero cross point of AC input
voltage. The current decrease slope is steep near the
zero cross region and more negative inductor current
flows during a drain voltage valley detection time. Such
a negative inductor current cancels down the positive
current flows and input current becomes zero, called
“zero - cross distortion” in PFC.
proportional to the input voltage. Some portion of this
current is applied to the internal sawtooth generator
together with a fixed-current source. Theoretically the
fixed-current source and the capacitor at sawtooth
generator determine the maximum turn-on time when no
current is sourcing at ZCD clamp circuit and available
turn-on time gets shorter proportional to the ZCD
sourcing current.
V AUX
I IN
R ZCD
THD Optimizer
V CC
N
1
I INDUCTOR
ZCD
V ZCD
I MOSFET
I DIODE
I NEGATIVE
5
Zero Current
Detect
V REF
1.5V
MOSFET Gate
1.4V
150ns
reset
I MOT
C MOT
ON
ON
t
Sawtooth Generator
Figure 38.
Input and Output Current
Figure 40.
Circuit of THD Optimizer
Near Input Voltage Peak
t ON is typically constant over 1 AC line frequency
I IN
V ZCD
but t ON is changed by ZCD voltage.
t ON
I INDUCTOR
V ZCD
I NEGATIVE
t ON not shortter
t
t ON get shortter
V ZCD at FET on
1.5V
1.4V
150ns
Figure 41.
Effect of THD Optimizer
MOSFET Gate
By THD optimizer, turn-on time over one AC line period
ON
ON
ON
ON
is proportionally changed, depending on input voltage.
Near zero cross, lengthened turn-on time improves
t
THD performance.
Figure 39.
Input and Output Current Near
Input Voltage Peak Zero Cross
? 2010 Fairchild Semiconductor Corporation
FL7930B ? Rev. 1.0.4
16
www.fairchildsemi.com
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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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