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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： | 12/24頁 |
| 文件大小： | 726K |
| 代理商： | FSCQ0765RT |
FSCQ0765RT
12
Functional Description
.
Startup
: Figure 4 shows the typical startup circuit and
transformer auxiliary winding for FSCQ0765RT application.
Before FSCQ0765RT begins switching, FSCQ0765RT
consumes only startup current (typically 25uA) and the
current supplied from the AC line charges the external
capacitor (C
a1
) that is connected to the Vcc pin. When Vcc
reaches start voltage of 15V (V
START
), FSCQ0765RT begins
switching, and the current consumed by FSCQ0765RT
increases to 4mA. Then, FSCQ0765RT continues its normal
switching operation and the power required for this device is
supplied from the transformer auxiliary winding, unless Vcc
drops below the stop voltage of 9V (V
STOP
). To guarantee the
stable operation of the control IC, Vcc has under voltage
lockout (UVLO) with 6V hysteresis. Figure 5 shows the
relation between the FSCQ0765RT operating supply current
and the supply voltage (Vcc).
1
.
.
Figure 4. Startup circuit
Figure 5. Relation between operating supply current and
Vcc voltage
The minimum average of the current supplied from the AC is
given by
where
V
ac
min
is the minimum input voltage, V
start
is the
FSCQ0765RT start voltage (15V) and R
str
is the startup
resistor. The startup resistor should be chosen so that I
sup
avg
is larger than the maximum startup current (50uA).
Once the resistor value is determined, the maximum loss in
the startup resistor is obtained as
where
V
ac
max
is the maximum input voltage. The startup
resistor should have proper rated dissipation wattage.
2. Synchronization :
FSCQ0765RT employs quasi-resonant
switching technique to minimize the switching noise and loss.
In this technique, a capacitor (Cr) is added between the
MOSFET drain and source as shown in Figure 6. The basic
waveforms of quasi-resonant converter are shown in Figure
7. The external capacitor lowers the rising slop of drain
voltage to reduce the EMI caused when the MOSFET turns
off. In order to minimize the MOSFET switching loss, the
MOSFET should be turned on when the drain voltage reaches
its minimum value as shown in Figure 7.
Figure 6. Synchronization circuit
FSCQ0765RT
1N4007
Rstr
Vcc
C
a1
Da
I
sup
AC line
min
- V
ac
(V
ac
max
)
C
DC
C
a2
Icc
Vcc
Vstop=9V
25uA
4mA
Vstart=15V
Vz
Power Up
Power Down
I
sup
avg
2 V
min
-----------------------------
V
--------------
–
str
---------
=
Loss
R
str
---------
V
--------------------------------------------------
max
(
)
2
V
2
+
2
2 2 V
V
-----------------------------------------------------
max
–
=
V
cc
C
a1
D
a
C
DC
C
a2
GND
Cr
Drain
Ids
R
cc
R
SY1
R
SY2
Sync
+
V
DC
-
Lm
Vo
C
SY
+
V
ds
-
V
co
D
SY
Np
Ns
Na
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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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