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参数资料
| 型号： | FSEZ1317NY |
| 厂商： | Fairchild Semiconductor |
| 文件页数： | 10/17页 |
| 文件大小： | 0K |
| 描述： | IC PWM CTLR PRIMARY REG 7-DIP |
| 标准包装： | 59 |
| 输出隔离： | 隔离 |
| 频率范围： | 47kHz ~ 53kHz |
| 输入电压： | 5.5 V ~ 23 V |
| 输出电压： | 700V |
| 工作温度： | -40°C ~ 105°C |
| 封装/外壳： | 8-DIP（0.300"，7.62mm），7 引线 |
| 供应商设备封装： | 7-DIP |
| 包装： | 带卷 (TR) |
Functional Description
Figure 24 shows the basic circuit diagram of primary-
side regulated flyback converter, with typical waveforms
shown in Figure 25. 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.
primary-side regulation because 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 ), is
applied across the secondary-side inductor ( L m ? N s2 /
N p2 ) and the diode current (I D ) decreases linearly from
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
EA_I
V COMI
PWM
Control
V COMV
EA_V
I O
Estimator
Ref
t DIS
Detector
V O
Estimator
Ref
+
V DL
-
CS
V S
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 the 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
-
Controller
Figure 24. Simplified PSR Flyback Converter Circuit
I pk
zero. Thus, by sampling the winding voltage at the end
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.
I pk ?
N P
N S
I D . avg ? I o
Meanwhile, the output current can be estimated using
the peak drain current and inductor current discharge
time because output current is same as the average of
the diode current in steady state.
V F ?
N A
N S
V O ?
N A
N S
The output current estimator picks up the peak value of
the drain current with a peak detection circuit and
calculates the output current using the 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 technique
TRUECURRENT?, constant current (CC) output can
be precisely controlled.
Among the two error voltages, V COMV and V COMI , the
smaller 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
FSEZ1317 ? Rev. 1.0.5
10
Figure 25. Key Waveforms of DCM Flyback
Converter
www.fairchildsemi.com
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相关代理商/技术参数 |
参数描述 |
|---|---|
| FSEZ1317WAMY | 功能描述:初级与次级侧 PWM 控制器 PSR PWM Controller w/MOSFET RoHS:否 制造商:ON Semiconductor 输出端数量:1 开关频率:250 KHz 工作电源电压:- 0.3 V to + 28 V 最大工作温度:+ 85 C 最小工作温度:- 5 C 封装 / 箱体:SOIC-8 Narrow 封装:Reel |
| FSEZ13X7 | 制造商:FAIRCHILD 制造商全称:Fairchild Semiconductor 功能描述:Primary Side Regulated (PSR) Flyback Converter |
| FSEZ2007NY | 功能描述:电压模式 PWM 控制器 Low-Power Green-Mode EZSWITCH RoHS:否 制造商:Texas Instruments 输出端数量:1 拓扑结构:Buck 输出电压:34 V 输出电流: 开关频率: 工作电源电压:4.5 V to 5.5 V 电源电流:600 uA 最大工作温度:+ 125 C 最小工作温度:- 40 C 封装 / 箱体:WSON-8 封装:Reel |
| FSEZ2016 | 制造商:FAIRCHILD 制造商全称:Fairchild Semiconductor 功能描述:Low-Power Green-Mode EZSWITCHTM without Secondary Side Feedback Circuitry |
| FSEZ2016_10 | 制造商:FAIRCHILD 制造商全称:Fairchild Semiconductor 功能描述:Low-Power Green-Mode EZSWITCH without Secondary Side Feedback Circuitry |
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