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| 型号： | FSQ0370RNA |
| 厂商： | Fairchild Semiconductor |
| 文件页数： | 10/17页 |
| 文件大小： | 0K |
| 描述： | IC SWIT PWM GREEN OVP UVLO 8DIP |
| 产品变化通告： | Passivation Layer Change 07/Dec/2007 |
| 标准包装： | 50 |
| 输出隔离： | 隔离 |
| 频率范围： | 92kHz ~ 108kHz |
| 输入电压： | 9 V ~ 20 V |
| 输出电压： | 700V |
| 功率（瓦特）： | 27W |
| 工作温度： | 25°C ~ 140°C |
| 封装/外壳： | 8-DIP（0.300"，7.62mm） |
| 供应商设备封装： | 8-DIP |
| 包装： | 管件 |
| 产品目录页面： | 1222 (CN2011-ZH PDF) |
IC to detect the temperature of the SenseFET. When the
temperature exceeds approximately 140 ? C, thermal
shutdown is activated.
4.3 Over-Voltage Protection (OVP): In the event of a
malfunction in the secondary-side feedback circuit, or an
open feedback loop caused by a soldering defect, the
current through the opto-coupler transistor becomes
almost zero (see Figure 14). V FB climbs up in a similar
At this point, switching stops and the output voltage
starts to drop at a rate dependent on the standby current
load. This causes the feedback voltage to rise. Once it
passes V BURH , switching resumes. The feedback
voltage then falls and the process is repeated. Burst-
mode operation alternately enables and disables
switching of the SenseFET and reduces switching loss in
standby mode.
manner to the overload situation, forcing the preset
maximum current to be supplied to the SMPS until the
overload protection is activated. Because excess energy
is provided to the output, the output voltage may exceed
the rated voltage before the overload protection is
activated, resulting in the breakdown of the devices in
the secondary side. To prevent this situation, an Over-
Voltage Protection (OVP) circuit is employed. In general,
V FB
V BURH
V BURL
Current
Burst Operation
Burst Operation
Normal
Operation
V CC is proportional to the output voltage and the FPS
uses V CC instead of directly monitoring the output
Waveform
Switching OFF
Switching
OFF
voltage. If V CC exceeds 19V, the OVP circuit is activated,
resulting in termination of the switching operation. To
avoid undesired activation of OVP during normal
operation, V CC should be designed to be below 19V.
5. Soft-Start : The FPS has an internal soft-start circuit
that slowly increases the SenseFET current after start-
up, as shown in Figure 16. The typical soft-start time is
10ms, where progressive increments of the SenseFET
current are allowed during the start-up phase. The pulse
width to the power switching device is progressively
increased to establish the correct working conditions for
transformers, inductors, and capacitors. The voltage on
FSQ0x70RNA Rev.00
Figure 17. Burst Operation Function
7. Adjusting Peak Current Limit: As shown in Figure
18, a combined 2.8k ? internal resistance is connected to
the non-inverting lead on the PWM comparator. An
external resistance of Rx on the current limit pin forms a
parallel resistance with the 2.8k ? when the internal
diodes are biased by the main current source of 900μA.
the output capacitors is progressively increased to
smoothly establish the required output voltage. This also
V CC
5 ? A
V CC
900 ? A
PWM
helps prevent transformer saturation and reduces the
V FB
I DELAY
I FB
2k Ω
Comparator
stress on the secondary diode during startup.
3
0.8k Ω
5V
#6,7,8
I PK
DRAIN
4
SenseFET
Current
Sense
Rx
FSQ0x70RNA Rev. 1.00
#1
GND
Figure 18. Peak Current Limit Adjustment
I LIM
R sense
For example, FSQ0270RNA has a typical SenseFET
peak current limit (I LIM ) of 0.9A. I LIM can be adjusted to
FSQ0x70RNA Rev. 1.00
Figure 16. Soft-Start Function
6. Burst Operation: To minimize power dissipation in
standby mode, the FPS enters burst-mode operation.
Feedback voltage decreases as the load decreases, as
shown in Figure 17, and the device automatically enters
burst-mode when the feedback voltage drops below
V BURH (typically 600mV). Switching continues until the
feedback voltage drops below V BURL (typically 400mV).
? 2006 Fairchild Semiconductor Corporation
FSQ0170RNA, FSQ0270RNA Rev. 1.0.5
10
0.6A by inserting Rx between the I PK pin and the ground.
The value of the Rx can be estimated by the following
equations:
0.9A: 0.6A = 2.8k ? : Xk ? ,
X = Rx || 2.8k ?
where X represents the resistance of the parallel network.
www.fairchildsemi.com
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相关代理商/技术参数 |
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| FSQ0370RNA_12 | 制造商:FAIRCHILD 制造商全称:Fairchild Semiconductor 功能描述:Green Mode Fairchild Power Switch (FPSa?￠) |
| FSQ0465RB | 制造商:FAIRCHILD 制造商全称:Fairchild Semiconductor 功能描述:Green-Mode Fairchild Power Switch (FPS) for Quasi-Resonant Operation - Low EMI and High Efficiency |
| FSQ0465RBLDTU | 功能描述:电源开关 IC - 配电 SMPS Power switch (QRC) 4A 650V RoHS:否 制造商:Exar 输出端数量:1 开启电阻（最大值）:85 mOhms 开启时间（最大值）:400 us 关闭时间（最大值）:20 us 工作电源电压:3.2 V to 6.5 V 电源电流（最大值）: 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOT-23-5 |
| FSQ0465RBWDTU | 功能描述:电源开关 IC - 配电 SMPS Power switch (QRC) 4A 650V RoHS:否 制造商:Exar 输出端数量:1 开启电阻（最大值）:85 mOhms 开启时间（最大值）:400 us 关闭时间（最大值）:20 us 工作电源电压:3.2 V to 6.5 V 电源电流（最大值）: 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOT-23-5 |
| FSQ0465RS | 制造商:FAIRCHILD 制造商全称:Fairchild Semiconductor 功能描述:Green-Mode Fairchild Power Switch (FPS) for Quasi-Resonant Operation - Low EMI and High Efficiency |
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