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| 型号： | FAN4800AUN |
| 厂商： | Fairchild Semiconductor |
| 文件页数： | 15/19页 |
| 文件大小： | 1414K |
| 描述： | IC PWM/PFC CTLR COMBO 16-MDIP |
| 标准包装： | 1,800 |
| 模式： | 平均电流 |
| 频率 - 开关： | 240kHz ~ 268kHz |
| 电流 - 启动： | 30µA |
| 电源电压： | 11 V ~ 22 V |
| 工作温度： | -40°C ~ 105°C |
| 安装类型： | 通孔 |
| 封装/外壳： | 16-DIP（0.300"，7.62mm） |
| 供应商设备封装： | 16-MDIP |
| 包装： | 管件 |
?2011 Fairchild Semiconductor Corporation
www.fairchildsemi.com
FAN4800AU/CU " Rev. 1.0.1
15
Voltage Control of Boost Stage
The voltage-control loop regulates PFC output voltage
using an internal error amplifier such that the FB
voltage is the same as the internal reference of 2.5 V.
Brownout Protection
The built-in internal brownout protection comparator
monitors the voltage of the VRMS pin. Once VRMS pin
voltage is lower than 1.05 V, the PFC stage is shut
down to protect the system from over current.
FAN4800AU/CU starts up the boost stage once VRMS
voltage increases above 1.9 V.
TriFault Detect"
To improve power supply reliability, reduce system
component count, and simplify compliance to UL 1950
safety standards, the FAN4800AU/CU includes
Fairchilds TriFault Detect technology.
In a feedback path failure, the output voltage of the PFC
can exceed safe operating limits. TriFaultDetect
protects the power supply from a failure related to the
output feedback by monitoring the FBPFC voltage.
TriFaultDetect is an entirely internal circuit. It requires
no external components to serve its protective function.
V
BO U T
R
FB 1
R
FB 2
F B P F C
D isable O P F C
TriFaultD etect
+
-
+
-
0.5V
2.75V
V
D D
300nA
Figure 34. TriFault Detect"
PWM Stage
The PWM stage is capable of Current Mode or Voltage
Mode operation. In Current-Mode, the PWM ramp
(RAMP) is usually derived directly from a current-
sensing resistor or current transformer in the primary
side of the output stage, and is thereby representative
of the current flowing in the converters output stage.
I
LIMIT
, which provides cycle-by-cycle current limiting, is
typically connected to RAMP in such applications.
For Voltage-Mode operation, RAMP can be connected to
a separate RC timing network to generate a voltage ramp
against which the FBPWM voltage is compared. Under
these conditions, the voltage feed-forward from the PFC
bus can be used for better line transient response.
No voltage error amplifier is included in the PWM stage,
as this function is generally performed by KA431, in the
secondary side. To facilitate the design of opto-coupler
feedback circuitry, an offset voltage is built into the
inverting input of PWM comparator. This allows
FBPWM to command a zero percent duty cycle when
its pin voltage is below 1.5V.
V
B O U T
R A M P
R
R A M P
C
R A M P
R E F
+
-
P W M
F B P W M
1.5V
Figure 35. PWM Ramp Generation Circuit
PWM Current Limit
The ILIMIT pin is a direct input to the cycle-by-cycle
current limiter for the PWM section. If the input voltage
at this pin exceeds 1 V, the output of the PWM is
disabled for until the start of the next PWM clock cycle.
V
IN
OK Comparator
The V
IN
OK comparator monitors the output of the PFC
stage and inhibits the PWM stage if this voltage is less
than 2.4 V (96% of its nominal value). Once this voltage
goes above 2.4 V, the PWM stage begins soft-start.
The PWM stage is shut down when FBPFC voltage
drops below 1.3 V.
PWM Soft-Start (SS)
PWM startup is controlled by the soft-start capacitor. A
current source of 10 礎 supplies the charging current
for the soft-start capacitor. PWM startup is prohibited
until the soft-start capacitor voltage reaches 1.5 V.
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| FAN4802MY | IC PFC CTRLR AVERAGE CURR 16SOP |
| FAN4802SNY | IC CTLR PFC/PWM COMBO 16-PDIP |
| FAN6920MRMY | IC PWM CTLR PFC/QUASI-RES 16SOP |
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相关代理商/技术参数 |
参数描述 |
|---|---|
| FAN4800C | 制造商:FAIRCHILD 制造商全称:Fairchild Semiconductor 功能描述:PFC/PWM Controller Combination |
| FAN4800CMY | 功能描述:电流型 PWM 控制器 PWM/PFC, Avg Curr 30uA SU, 2.6mA Op RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
| FAN4800CNY | 功能描述:电流型 PWM 控制器 PWM/PFC, Avg Curr 30uA SU, 2.6mA Op RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
| FAN4800CS | 制造商:FAIRCHILD 制造商全称:Fairchild Semiconductor 功能描述:PFC/PWM Controller Combination |
| FAN4800CSMY | 功能描述:电流型 PWM 控制器 PFC/PWM Controller Combination RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
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