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參數資料
| 型號： | FSCM0565R |
| 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： | 10/20頁 |
| 文件大小： | 346K |
| 代理商： | FSCM0565R |
FSCM0565R
10
Functional Description
.
Startup
: Figure 4 shows the typical startup circuit and
transformer auxiliary winding for FSCM0565R application.
Before FSCM0565R begins switching, FSCM0565R
consumes only startup current (typically 25uA) and the
current supplied from the DC link supply ccurrent consumed
by FPS (Icc) and charges the external capacitor (C
a
) that is
connected to the Vcc pin. When Vcc reaches start voltage of
12V (V
START
), FSCM0565R begins switching, and the
current consumed by FSCM0565R increases to 3mA. Then,
FSCM0565R 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 8V (V
STOP
). To guarantee the stable operation
of the control IC, Vcc has under voltage lockout (UVLO)
with 4V hysteresis. Figure 5 shows the relation between the
current consumed by FPS (Icc) and the supply voltage (Vcc).
1
Figure 4. Startup circuit
Figure 5. Relation between operating supply current and
Vcc voltage
The minimum current supplied through the startup resistor is
given by
where
V
line
min
is the minimum input voltage,
V
start
is the
start voltage (12V) and
R
str
is the startup resistor. The startup
resistor should be chosen so that
I
sup
min
is larger than the
maximum startup current (40uA). If not, Vcc can not be
charged to the start voltage and FPS will fail to start up.
2. Feedback Control
: FSCM0565R employs current mode
control, as shown in Figure 6. An opto-coupler (such as the
H11A817A) and shunt regulator (such as the KA431) are
typically used to implement the feedback network.
Comparing the feedback voltage with the voltage across the
Rsense resistor makes it possible to control the switching
duty cycle. When the reference pin voltage of the KA431
exceeds the internal reference voltage of 2.5V, the
H11A817A LED current increases, thus pulling down the
feedback voltage and reducing the duty cycle. This event
typically happens when the input voltage is increased or the
output load is decreased.
2.1 Pulse-by-pulse current limit
: Because current mode
control is employed, the peak current through the Sense FET
is determined by the inverting input of PWM comparator
(Vfb*) as shown in Figure 6. When the current through the
opto transistor is zero and the current limit pin (#5) is left
floating, the feedback current source (I
FB
) of 0.9mA flows
only through the internal resistor (R+2.5R=2.8k). In this
case, the cathode voltage of diode D2 and the peak drain
current have maximum values of 2.5V and 2.5A, respec-
tively. The pulse-by-pulse current limit can be adjusted using
a resistor to GND on current limit pin (#5). The current limit
level using an external resistor (R
LIM
) is given by
Figure 6. Pulse width modulation (PWM) circuit
FSCM0565R
Rstr
Vcc
Ca
Da
I
sup
AC line
min
- V
line
(V
line
max
)
C
DC
I
cc
Icc
Vcc
Vstop=8V
25uA
3mA
Vstart=12V
Vz
Power Up
Power Down
Isup
min
2 V
line
min
V
start
–
(
)
Rstr
=
I
LIM
R
2.5
A
2.8k
+
R
LIM
------------------------------------
=
4
OSC
Vcc
Vref
I
delay
I
FB
V
SD
R
2.5R
Gate
driver
OLP
D1
D2
+
V
fb
*
-
Vfb
KA431
C
B
Vo
H11A817A
R
sense
SenseFET
5
R
LI M
0.9mA
0.3k
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相關代理商/技術參數 |
參數描述 |
|---|---|
| FSCM0565RBIWDTU | 制造商:Fairchild Semiconductor Corporation 功能描述: |
| FSCM0565RC | 制造商:FAIRCHILD 制造商全稱:Fairchild Semiconductor 功能描述:Green Mode Fairchild Power Switch (FPS) |
| FSCM0565RCYDTU | 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 |
| FSCM0565RD | 制造商:Fairchild Semiconductor Corporation 功能描述:POWER SWITCH SMPS GREEN D2-PAK-5 |
| FSCM0565RG | 制造商:FAIRCHILD 制造商全稱:Fairchild Semiconductor 功能描述:Green Mode Fairchild Power Switch |
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