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參數(shù)資料
| 型號： | FAN7930BM |
| 廠商： | Fairchild Semiconductor |
| 文件頁數(shù)： | 15/22頁 |
| 文件大?。?/td> | 1849K |
| 描述： | IC PFC CTLR CRITICAL CONF 8-SOIC |
| 標準包裝： | 95 |
| 模式： | 臨界傳導（CRM） |
| 頻率 - 開關： | 250kHz ~ 350kHz |
| 電流 - 啟動： | 120µA |
| 電源電壓： | 13 V ~ 20 V |
| 工作溫度： | -40°C ~ 125°C |
| 安裝類型： | 表面貼裝 |
| 封裝/外殼： | 8-SOIC（0.154"，3.90mm 寬） |
| 供應商設備封裝： | 8-SOP |
| 包裝： | 管件 |
?2010 Fairchild Semiconductor Corporation
www.fairchildsemi.com
FAN7930B " Rev. 1.0.3
15
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
becomes zero, resonance between C
OSS
and the boost
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.
1. 5 V
1 5 0 n s
1 . 4 V
O N
V
ZC D
I
I N D U C T O R
M O S F E T G a t e
I
N E G A T I V E
O N
I
I N
I
M O S F E T
I
D I O D E
Figure 37. Input and Output Current
Near Input Voltage Peak
1 . 5 V
1 5 0 n s
1 . 4 V
O N
O N
V
Z C D
I
I N D U C T O R
M O S F E T G a t e
I
N E G A T I V E
O N
O N
I
I N
Figure 38. Input and Output Current Near
Input Voltage Peak Zero Cross
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. FAN7930B
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.
The sourcing current from the ZCD is directly
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.
R
Z C D
V
A U X
Z C D
Z e r o C u r r e n t
D e t e c t
5
V CC
N
1
V R E F
I M O T
re s e t
S a w t o o t h G e n e r a t o r
C M O T
T H D O p tim iz e r
Figure 39. Circuit of THD Optimizer
V
Z C D
t
ON
t
V
Z C D
a t F E T o n
t
O N
g e t s h o r tte r
t
O N
n o t s h o r tte r
t
O N
is ty p ic a lly c o n s ta n t o v e r 1 A C lin e fr e q u e n c y
b u t t
O N
is c h a n g e d b y Z C D v o lta g e .
Figure 40. Effect of THD Optimizer
By THD optimizer, turn-on time over one AC line period
is proportionally changed, depending on input voltage.
Near zero cross, lengthened turn-on time improves
THD performance.
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相關代理商/技術參數(shù) |
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|---|---|
| FAN7930BMX | 功能描述:功率因數(shù)校正 IC Critical Conduction Mode PFC Controller RoHS:否 制造商:Fairchild Semiconductor 開關頻率:300 KHz 最大功率耗散: 最大工作溫度:+ 125 C 安裝風格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝: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 制造商全稱: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:功率因數(shù)校正 IC Critical Conduction Mode PFC Controller RoHS:否 制造商:Fairchild Semiconductor 開關頻率:300 KHz 最大功率耗散: 最大工作溫度:+ 125 C 安裝風格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Reel |
| FAN7930CMX | 功能描述:功率因數(shù)校正 IC Critical Conduction Mode PFC Controller RoHS:否 制造商:Fairchild Semiconductor 開關頻率:300 KHz 最大功率耗散: 最大工作溫度:+ 125 C 安裝風格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Reel |
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