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參數資料
| 型號： | FSCQ0765RT |
| 廠商： | Fairchild Semiconductor Corporation |
| 英文描述： | Green Mode Fairchild Power Switch (FPS) for Quasi-Resonant Switching Converter |
| 中文描述： | 綠色模式飛兆半導體功率開關（FPS）的準諧振開關變換器 |
| 文件頁數： | 15/24頁 |
| 文件大小： | 726K |
| 代理商： | FSCQ0765RT |
FSCQ0765RT
15
Figure 12. Auto restart mode protection
4.1 Over Load Protection (OLP) :
Overload is defined as
the load current exceeding its normal level due to an
unexpected abnormal event. In this situation, the protection
circuit should trigger in order to protect the SMPS. However,
even when the SMPS is in the normal operation, the over
load protection circuit can be triggered during the load
transition. In order to avoid this undesired operation, the
over load protection circuit is designed to trigger after a
specified time to determine whether it is a transient situation
or an overload situation. Because of the pulse-by-pulse
current limit capability, the maximum peak current through
the Sense FET is limited, and therefore the maximum input
power is restricted with a given input voltage. If the output
consumes more than this maximum power, the output
voltage (Vo) decreases below the set voltage. This reduces
the current through the opto-coupler LED, which also
reduces the opto-coupler transistor current, thus increasing
the feedback voltage (Vfb). If Vfb exceeds 2.8V, D1 is
blocked and the 5uA current source starts to charge C
B
slowly up to Vcc. In this condition, Vfb continues increasing
until it reaches 7.5V, when the switching operation is
terminated as shown in Figure 13. The delay time for
shutdown is the time required to charge C
B
from 2.8V to
7.5V with 5uA. In general, a 20 ~ 50 ms delay time is typical
for most applications. This protection is implemented in auto
restart mode.
Figure 13. Over load protection
4.2 Abnormal Over Current Protection (AOCP)
: When
the secondary rectifier diodes or the transformer pins are
shorted, a steep current with extremely high di/dt can flow
through the SenseFET during the LEB time. Even though the
FSCQ0765RT has OLP (Over Load Protection), it is not
enough to protect the FSCQ0765RT in that abnormal case,
since sever current stress will be imposed on the SenseFET
until OLP triggers. The FSCQ0765RT has an internal AOCP
(Abnormal Over Current Protection) circuit as shown in
Figure 14. When the gate turn-on signal is applied to the
power Sense FET, the AOCP block is enabled and monitors
the current through the sensing resistor. The voltage across
the resistor is then compared with a preset AOCP level. If
the sensing resistor voltage is greater than the AOCP level,
the set signal is applied to the latch, resulting in the
shutdown of SMPS. This protection is implemented in latch
mode.
Figure 14. AOCP block
4.3 Over voltage Protection (OVP)
: If the secondary side
feedback circuit were to malfunction or a solder defect
caused an open in the feedback path, the current through the
opto-coupler transistor becomes almost zero. Then, Vfb
climbs up in a similar manner to the over load situation,
Fault
situation
9V
15V
Vcc
Vds
I
op
4mA
25uA
t
Fault
occurs
Fault
removed
Normal
operation
Normal
operation
Power
on
V
FB
t
2.8V
7.5V
Over load protection
T
12
= C
B
*(7.5-2.8)/I
delay
T
1
T
2
2
S
Q
Q
R
OSC
R
2.5R
GND
Gate
driver
LEB
PWM
+
-
Vaocp
AOCP
R
sense
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相關代理商/技術參數 |
參數描述 |
|---|---|
| FSCQ0765RTYDTU | 功能描述:軟開關 PWM 控制器 7A/650V QRC Power Switch RoHS:否 制造商:Fairchild Semiconductor 輸出端數量: 輸出電流: 開關頻率: 工作電源電壓:30 V 電源電流: 最大工作溫度:+ 105 C 最小工作溫度:- 40 C 安裝風格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Reel |
| FSCQ0965RT | 制造商:FAIRCHILD 制造商全稱:Fairchild Semiconductor 功能描述:Green Mode Fairchild Power Switch (FPS TM) |
| FSCQ0965RTYDTU | 功能描述:軟開關 PWM 控制器 POWER_CONVERSION RoHS:否 制造商:Fairchild Semiconductor 輸出端數量: 輸出電流: 開關頻率: 工作電源電壓:30 V 電源電流: 最大工作溫度:+ 105 C 最小工作溫度:- 40 C 安裝風格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Reel |
| FSCQ1265RT | 制造商:FAIRCHILD 制造商全稱:Fairchild Semiconductor 功能描述:Green Mode Fairchild Power Switch (FPS TM) |
| FSCQ1265RTYDTU | 功能描述:開關變換器、穩壓器與控制器 12A/650V QRC Power Switch RoHS:否 制造商:Texas Instruments 輸出電壓:1.2 V to 10 V 輸出電流:300 mA 輸出功率: 輸入電壓:3 V to 17 V 開關頻率:1 MHz 工作溫度范圍: 安裝風格:SMD/SMT 封裝 / 箱體:WSON-8 封裝:Reel |
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