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參數資料
| 型號： | FA3647N |
| 廠商： | FUJI ELECTRIC CO LTD |
| 元件分類： | 穩壓器 |
| 英文描述： | PWM control IC with light load power saving function For Switching Power Supply Control |
| 中文描述： | 1 A SWITCHING CONTROLLER, 500 kHz SWITCHING FREQ-MAX, PDSO8 |
| 封裝： | SOP-8 |
| 文件頁數： | 10/21頁 |
| 文件大小： | 406K |
| 代理商： | FA3647N |
FA3641P(N), FA3647P(N)
67
Fig. 10 Overload shutdown circuit
4.2 Overload shutdown function
Figure 10 shows the overload shutdown circuit, and Figure 11
is a timing chart that illustrates overload shutdown operation.
If the output voltage drops due to an overload or short circuit,
the FB pin output voltage rises. If the FB pin voltage exceeds
the reference voltage (3.0V) of comparator C3, the output of
comparator C3 goes low to turn off the switch. With the switch
off, the CS pin voltage clamped at 4.0V by zener diode in
normal operation is unclamped, and the constant current
source (6.5
μ
A) begins to charge capacitor Cs again and the CS
pin voltage rises. When the CS pin voltage exceeds the
reference voltage (8.5V) of comparator C2, the output of
comparator C2 toggles to turn off the 5V REF circuit. The IC
then enters the latched mode and shuts down the output. IC
current consumption for shutdown is 45
μ
A (typ) (Vcc = 10V).
This current must be supplied through the startup resistor. The
IC enters output off (low voltage) state.
The overload shutdown operation can be reset by lowering the
supply voltage Vcc to below the OFF threshold voltage (9.0V)
or forcing the CS pin voltage below 7.9V.
The period t
OL
from the time the output is short-circuited to the
time the output circuit goes off is given by the following
equation:
t
OL
[ms] 690 Cs
.................................................. (4)
Cs: Soft start capacitor [
μ
F]
When you want to disable the overload shutdown function, see
item 11 in
“
Design advice
”
4.3 Output ON/OFF control function
The IC can be turned on or off via an external signal applied to
the CS pin. Figure 12 shows the output on/off control circuit,
and Figure 13 is a timing chart.
The IC is turned off when the CS pin voltage is externally made
to drop below 0.68V (typ). The output of comparator C1 goes
high to turn the 5V REF circuit. This shuts the output down.
The IC enters output off (low voltage) state. Required IC
current consumption during shutdown is 100
μ
A (typ) (Vcc =
17V). This current must be supplied through the startup
resistor. The IC goes on when the CS pin is opened and the
CS pin voltage exceeds 0.82V (typ). This turns on the 5V REF
circuit and results in automatic soft start. The power supply
then restarts operation.
Fig. 11 Overload shutdown timing chart
Fig. 12 External output ON/OFF control circuit
Fig. 13 Output ON/OFF control circuit timing chart
相關PDF資料 |
PDF描述 |
|---|---|
| FA3647P | PWM control IC with light load power saving function For Switching Power Supply Control |
| FA365 | THIN SMD HIGH-FREQUENCY CRYSTAL UNIT |
| FA-365 | THIN SMD HIGH-FREQUENCY CRYSTAL UNIT |
| FA3675F | For Switching Power Supply Control |
| FA3863X | SUPER BRIGHT LED |
相關代理商/技術參數 |
參數描述 |
|---|---|
| FA3647N-H1 | 制造商:Fuji Electric 功能描述: |
| FA3647P | 制造商:FUJI 制造商全稱:Fuji Electric 功能描述:PWM control IC with light load power saving function For Switching Power Supply Control |
| FA3647P-D1 | 制造商:Fuji Electric 功能描述: |
| FA365 | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:THIN SMD HIGH-FREQUENCY CRYSTAL UNIT |
| FA-365 | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:THIN SMD HIGH-FREQUENCY CRYSTAL UNIT |
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