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參數(shù)資料
| 型號： | FAN7930CM |
| 廠商： | Fairchild Semiconductor |
| 文件頁數(shù)： | 13/22頁 |
| 文件大?。?/td> | 1725K |
| 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(guān)： | 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(yīng)商設(shè)備封裝： | 8-SOP |
| 包裝： | 管件 |
?2010 Fairchild Semiconductor Corporation
www.fairchildsemi.com
FAN7930C " Rev. 1.0.2
13
ISW
V
A U X
& V
Z C D
V AC I N
I
M O S F E T
I
D I O D E
V A U X
V
Z C D
t
6 . 2 V
0 . 6 5 V
Figure 28. Auxiliary Voltage Depends on
MOSFET Switching
The auxiliary winding voltage is used to check the boost
inductor current zero instance. When boost inductor
current becomes zero, there is a resonance between
boost inductor and all capacitors at the MOSFET drain
pin: including C
OSS
of the MOSFET; an external
capacitor at the D-S pin to reduce the voltage rising and
falling slope of the MOSFET; a parasitic capacitor at
inductor; and so on to improve performance. Resonated
voltage is reflected to the auxiliary winding and can be
used for detecting zero current of boost inductor and
valley position of MOSFET voltage stress. For valley
detection, a minor delay by the resistor and capacitor is
needed. A capacitor increases the noise immunity at the
ZCD pin. If ZCD voltage is higher than 1.5 V, an internal
ZCD comparator output becomes HIGH and LOW when
the ZCD goes below 1.4 V. At the falling edge of
comparator output, internal logic turns on the MOSFET
V
IN
V
O U T
P F C
- V
I N
1 . 5 V
1 5 0 n s D e la y
1 . 4 V
O N
O N
V
O U T
P F C
- V
I N
I
M O S F E T
I
D I O D E
V
Z C D
I
I N D U C T O R
V
D S
M O S F E T g a t e
Figure 29. Auxiliary Voltage Threshold
When no ZCD signal is available, the PFC controller
cannot turn on the MOSFET, so the controller checks
every switching off time and forces MOSFET turn on
when the off time is longer than 150 約. This restart
timer triggers MOSFET turn-on at startup and may be
used at the input voltage zero-cross period.
V
O U T
V
I N
V
C C
t
R E S T A R T
M O S F E T g a t e
Z C D
a f t e r C O M P A R A T O R
Figure 30. Restart Timer at Startup
Because the MOSFET turn-on depends on the ZCD
input, switching frequency may increase to higher than
several megahertz due to the mis-triggering or noise on
the nearby ZCD pin. If the switching frequency is higher
than needed for critical conduction mode (CRM),
operation mode shifts to continuous conduction mode
(CCM). In CCM, unlike CRM where the boost inductor
current is reset to zero at the next switch on; inductor
current builds up at every switching cycle and can be
raised to very high current that exceeds the current
rating of the power switch or diode. This can seriously
damage the power switch. To avoid this, maximum
switching frequency limitation is embedded. If ZCD
signal is applied again within 3.3 約 after the previous
rising edge of gate signal, this signal is ignored
internally and FAN7930C waits for another ZCD signal.
This slightly degrades the power factor performance at
light load and high input voltage.
Z C D a f t e r C O M P A R A T O R
O S F E T G a t e
M a x . f S W L i m i t
I n h i b i t R ei o n
E r r o r o c c u r s !
I g n o r e s Z C D n o i s e
t
Figure 31. Maximum Switching Frequency
Limit Operation
6. Control: The scaled output is compared with the
internal reference voltage and sinking or sourcing
current is generated from the COMP pin by the
transconductance amplifier. The error amplifier output is
compared with the internal sawtooth waveform to give
proper turn-on time based on the controller.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| 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(guān)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_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 |
| FAN7930DM | 制造商:Fairchild Semiconductor Corporation 功能描述:PFC |
| FAN7930DMX | 制造商:Fairchild Semiconductor Corporation 功能描述:PFC |
| FAN7930M | 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(guān)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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