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參數(shù)資料
| 型號： | FSCQ |
| 廠商： | Fairchild Semiconductor Corporation |
| 英文描述： | Green Mode Fairchild Power Switch (FPS) |
| 中文描述： | 綠色模式飛兆半導體功率開關（FPS） |
| 文件頁數(shù)： | 14/44頁 |
| 文件大?。?/td> | 1204K |
| 代理商： | FSCQ |
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FSCQ-SERIES
14
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.
Choose
voltage dividers, R
SY1
and R
SY2,
so that the
peak voltage of the sync signal (V
sypk
) is lower than the
OVP voltage (12V)
to
avoid triggering OVP in normal
operation. It is typical to set V
sypk
to be lower than OVP
voltage by 3-4 V.
T
o 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,
and
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 the MOSFET and the external capacitor, Cr.
Figure 8. Normal Quasi-Resonant Operation Waveforms
Figure 9. Extended Quasi-Resonant Operation
In general, the QRC 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.
To
overcome
this limitation, the
FSCQ-Series employs an extended quasi-resonant switching
operation. Figure 9 shows the mode change between normal
and extended quasi-resonant operations. In the normal quasi-
resonant operation, the FSCQ-Series enters into the extended
quasi-resonant operation when the switching frequency
exceeds 90kHz as the load
reduces
. To reduce the switching
frequency, the MOSFET is turned on when the drain voltage
reaches the second minimum level, as shown in Figure 10.
V
DC
V
RO
V
RO
I
pk
I
ds
V
d
s
V
gs
MOSFET
Off
MOSFET
On
T
R
R
SY2
C
SY
V
2.6
--------
R
+
R
SY1
R
SY2
----------------------------------
ln
=
T
Q
π
L
m
C
eo
=
V
co
N
---------------------+
V
N
s
)
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
相關PDF資料 |
PDF描述 |
|---|---|
| FSCQ1465RT | Green Mode Fairchild Power Switch (FPS) |
| FSCQ1565RP | Green Mode Fairchild Power Switch (FPS) for Quasi-Resonant Switching Converter |
| FSCQ1565RPSYDTU | Green Mode Fairchild Power Switch (FPS) for Quasi-Resonant Switching Converter |
| FSCQ0965RTYDTU | Green Mode Fairchild Power Switch (FPS) |
| FSCQ1465RTYDTU | Green Mode Fairchild Power Switch (FPS) |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| FSCQ_06 | 制造商:FAIRCHILD 制造商全稱:Fairchild Semiconductor 功能描述:Green Mode Fairchild Power Switch (FPS⑩) |
| FSCQ0565RT | 制造商:FAIRCHILD 制造商全稱:Fairchild Semiconductor 功能描述:Green Mode Fairchild Power Switch (FPS) |
| FSCQ0565RTYDTU | 功能描述:電源開關 IC - 配電 5A 650V QRC PwrSwtch RoHS:否 制造商:Exar 輸出端數(shù)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 |
| FSCQ0765RT | 制造商:FAIRCHILD 制造商全稱:Fairchild Semiconductor 功能描述:Green Mode Fairchild Power Switch (FPS) |
| 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(shù)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 |
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