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參數資料
| 型號： | FSCQ1265RT |
| 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： | 13/24頁 |
| 文件大小： | 726K |
| 代理商： | FSCQ1265RT |
FSCQ0765RT
13
Figure 7. Quasi-resonant operation waveforms
The minimum drain voltage is indirectly detected by
monitoring the Vcc winding voltage as shown in Figure 6
and 8. The voltage divider R
SY1
and R
SY2
should be chosen so
that the peak voltage of sync signal (V
sypk
) is lower than the
OVP voltage (12V) in order to avoid triggering OVP in
normal operation. It is typical to set V
sypk
to be lower than
OVP voltage by 3-4 V. In order to detect the optimum time to
turn on MOSFET, the sync capacitor (C
SY
) should be
determined so that T
R
is the same with T
Q as shown in Figure
8
. The T
R
and T
Q
are given as, respectively
where L
m
is the primary side inductance of the transformer,
N
s
and N
a
are the number of turns for the output winding and
Vcc winding, respectively, V
Fo
and V
Fa
are the diode
forward voltage drops of the output winding and Vcc
winding, respectively, and C
eo
is the sum of the output
capacitance of MOSFET and external capacitor Cr.
Figure 8. Normal quasi-resonant operation waveforms
Figure 9. Extended quasi-resonant operation
In general, quasi-resonant converter has a limitation in a
wide load range application, since the switching frequency
increases as the output load decreases, resulting in a severe
switching loss in the light load condition. In order to get over
this limitation, FSCQ0765RT employs extended quasi-
resonant switching operation. Figure 9 shows the mode
change between normal quasi-resonant operation and
extended quasi-resonant operation. In the normal quasi-
resonant operation, the FSCQ0765RT enters into the
extended quasi-resonant operation when the switching
frequency exceeds 90kHz as the load reduces. Then, the
MOSFET is turned on, when the drain voltage reaches the
V
DC
V
RO
V
RO
I
pk
I
ds
V
ds
V
gs
MOSFET
off
MOSFET
on
T
R
R
SY2
C
SY
V
co
2.6
--------
R
+
R
SY1
R
SY2
----------------------------------
ln
=
T
Q
π
L
m
C
eo
=
V
co
N
----------------------------------------
V
s
V
+
)
V
Fa
–
=
Vsync
Vds
MOSFET Gate
2V
RO
Vrh (4.6V)
Vrf (2.6V)
ON
T
Q
T
R
ON
V
sypk
Output power
Switching
frequency
Normal QR operation
Extended QR operation
90kHz
45kHz
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|---|---|
| FSCQ0765RTYDTU | Green Mode Fairchild Power Switch (FPS) for Quasi-Resonant Switching Converter |
| FSCQ1265RTYDTU | Green Mode Fairchild Power Switch (FPS) |
| FSCQ1565RPVDTU | Green Mode Fairchild Power Switch (FPS⑩) |
| FSD1000 | Combo Fairchild Power Switch (FPS) |
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相關代理商/技術參數 |
參數描述 |
|---|---|
| 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 |
| FSCQ1465RT | 制造商:FAIRCHILD 制造商全稱:Fairchild Semiconductor 功能描述:Green Mode Fairchild Power Switch (FPS⑩) |
| FSCQ1465RTYDTU | 功能描述:電源開關 IC - 配電 POWER_CONVERSION RoHS:否 制造商:Exar 輸出端數量:1 開啟電阻（最大值）:85 mOhms 開啟時間（最大值）:400 us 關閉時間（最大值）:20 us 工作電源電壓:3.2 V to 6.5 V 電源電流（最大值）: 最大工作溫度:+ 85 C 安裝風格:SMD/SMT 封裝 / 箱體:SOT-23-5 |
| FSCQ1565RP | 制造商:FAIRCHILD 制造商全稱:Fairchild Semiconductor 功能描述:Green Mode Fairchild Power Switch (FPS TM) |
| FSCQ1565RPSYDTU | 功能描述:電源開關 IC - 配電 15A/650V QRC Power Switch RoHS:否 制造商:Exar 輸出端數量:1 開啟電阻（最大值）:85 mOhms 開啟時間（最大值）:400 us 關閉時間（最大值）:20 us 工作電源電壓:3.2 V to 6.5 V 電源電流（最大值）: 最大工作溫度:+ 85 C 安裝風格:SMD/SMT 封裝 / 箱體:SOT-23-5 |
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