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参数资料
| 型号： | FAN103MY |
| 厂商： | Fairchild Semiconductor |
| 文件页数： | 10/16页 |
| 文件大小： | 0K |
| 描述： | IC OFFLINE CTRLR PWM GREEN 8SOIC |
| 标准包装： | 1 |
| 输出隔离： | 隔离 |
| 频率范围： | 47kHz ~ 53kHz |
| 输入电压： | 5.5 V ~ 25 V |
| 功率（瓦特）： | 660mW |
| 工作温度： | -40°C ~ 105°C |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 供应商设备封装： | 8-SOICN |
| 包装： | 标准包装 |
| 产品目录页面： | 1221 (CN2011-ZH PDF) |
| 其它名称： | FAN103MYDKR |
Functional Description
Figure 21 shows the basic circuit diagram of a primary-
side regulated flyback converter with typical waveforms
shown in Figure 22. Generally, discontinuous
conduction mode (DCM) operation is preferred for
constant current regulation mode, V COMI determines the
duty cycle while V COMV is saturated to HIGH.
applied across the secondary-side inductor ( L m × N s /
N p ) and the diode current (I D ) decreases linearly from
primary-side regulation since it allows better output
regulation. The operation principles of DCM flyback
converter are as follows:
During the MOSFET on time (t ON ), input voltage (V DL ) is
applied across the primary-side inductor (L m ). Then,
MOSFET current (I ds ) increases linearly from zero to the
peak value (I pk ). During this time, the energy is drawn
from the input and stored in the inductor.
When the MOSFET is turned off, the energy stored in
the inductor forces the rectifier diode (D) to be turned
on. While the diode is conducting, the output voltage
(V o ), together with diode forward voltage drop (V F ), are
2
2
the peak value (I pk × N p /N s ) to zero. At the end of inductor
current discharge time (t DIS ), all the energy stored in the
inductor has been delivered to the output.
V AC
Gate
EA_I
V COMI
PWM
Control
V COMV
EA_V
Io
Estimator
Ref
t DIS
Detector
Vo
Estimator
Ref
+
V DL
-
CS
Vs
V DD
R CS
R S1
N p :N s
L m
I ds
N A
+
V w
I D
D
+ V F -
I o
+
V O
-
L
O
A
D
R S2
Primary-Side Regulation
When the diode current reaches zero, the transformer
auxiliary winding voltage (V w ) begins to oscillate by the
resonance between the primary-side inductor (L m ) and
the effective capacitor loaded across MOSFET.
During the inductor current discharge time, the sum of
output voltage and diode forward-voltage drop is
reflected to the auxiliary winding side as (V o +V F ) ×
N a /N s . Since the diode forward-voltage drop decreases
as current decreases, the auxiliary winding voltage
reflects the output voltage best at the end of diode
conduction time, where the diode current diminishes to
zero. Thus, by sampling the winding voltage at the end
-
Controller
Figure 21. Simplified PSR Flyback Converter Circuit
I pk
of the diode conduction time, the output voltage
information can be obtained. The internal error amplifier
for output voltage regulation (EA_V) compares the
sampled voltage with internal precise reference to
generate error voltage (V COMV ), which determines the
duty cycle of the MOSFET in CV mode.
Meanwhile, the output current can be estimated using
I pk ?
N P
N S
I D . avg = I o
the peak drain current and inductor current discharge
time since output current is same as average of the
diode current in steady state.
The output current estimator recognizes the peak value
V F ?
N A
N S
V O ?
N A
N S
of the drain current with a peak-detection circuit and
calculates the output current using inductor discharge
time (t DIS ) and switching period (t s ). This output
information is compared with internal precise reference
to generate error voltage (V COMI ), which determines the
duty cycle of the MOSFET in CC Mode. With Fairchild’s
innovative TRUECURRENT ? technique, constant
current (CC) output can be precisely controlled.
Among the two error voltages, V COMV and V COMI , the
small one determines the duty cycle. Therefore, during
constant voltage regulation mode, V COMV determines the
duty cycle while V COMI is saturated to HIGH. During
? 2010 Fairchild Semiconductor Corporation
FAN103 ? Rev. 1.0.7
10
Figure 22. Key Waveforms of DCM Flyback
Converter
www.fairchildsemi.com
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相关代理商/技术参数 |
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|---|---|
| FAN103WMY | 功能描述:电流型 PWM 控制器 Primary-Side-Reg PWM Controller 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 |
| FAN104W | 制造商:Fairchild 功能描述:5W~10W Mobile Charger |
| FAN104WMX | 功能描述:软开关 PWM 控制器 Hi Freq Primary Side Reg PWM Controller RoHS:否 制造商:Fairchild Semiconductor 输出端数量: 输出电流: 开关频率: 工作电源电压:30 V 电源电流: 最大工作温度:+ 105 C 最小工作温度:- 40 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-8 封装:Reel |
| FAN1084 | 制造商:FAIRCHILD 制造商全称:Fairchild Semiconductor 功能描述:4.5A Adjustable/Fixed Low Dropout Linear Regulator |
| FAN1084D | 制造商:FAIRCHILD 制造商全称:Fairchild Semiconductor 功能描述:4.5A Adjustable/Fixed Low Dropout Linear Regulator |
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