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參數資料
| 型號： | FA5305APS |
| 廠商： | FUJI ELECTRIC HOLDINGS CO., LTD. |
| 元件分類： | 基準電壓源/電流源 |
| 英文描述： | Bipolar IC For Switching Power Supply Control |
| 中文描述： | 雙極集成電路開關電源控制 |
| 文件頁數： | 11/17頁 |
| 文件大小： | 280K |
| 代理商： | FA5305APS |
FA5304AP(S)/FA5305AP(S)
11
(2) Startup circuit connected to rectified line
This method is not suitable for FA5304A and FA5305A,
especially concerned with re-startup operation just after power-
off or startup which AC input voltage goes up slowly. Fig. 21
shows a startup circuit that a startup resistor R
A
is connected
to rectified line directly.
The period from power-on to startup is determined by R
A
, R
B
and C
A
. R
A
, R
B
and C
A
must be designed to satisfy the
following equations.
dVcc/dt(V/s)=
(1/C
A
){( V
IN
–Vccon )/R
A
– Vccon/R
B
–Iccst } >
1.8/(Cs(
μ
F))................................................(8)
R
A
(k
)< (V
IN
– 9.2(V))/{0.4(mA) + (9.2(V)/R
B
(k
))}..............(9)
V
IN
:
E
2 (AC input effective voltage)
After power-off, once V
CC
falls down below OFF threshold
voltage, V
CC
rises up again and re-startup occurs while the
capacitor C
1
is discharged until approximately zero because
V
CC
voltage rises up by the current flowing R
A
.
This operation is repeated several times.
After the repeated operation, IC stops in the condition that V
CC
voltage is equal to Vccon
(=ON threshold) because capacitor
C
1
is discharged gradually and the decreased V
CC
inclination
is out of the condition required by equation (4).
After that, re-startup by power-on can not be guaranteed even
when equation (8) is satisfied. The image of that the startup is
impossible is shown in Fig. 22. It is necessary to startup IC
that supply current Icc (startup) to VCC is over 4mA in the
condition of Tj < 100
°
C during Vcc is kept at Vccon(
6
16V,
balance state at Vccon after the repeated operation.
Icc (start-up) > 4mA..............................(10)
at Vcc=Vccon, Tj<100
°
C, after power-off
This balance state that startup is impossible tends to occur at
higher temperature.
If power-on is done when Vcc is not kept at Vccon (for
example: power-off is done and after enough time that C
1
is
discharged until Vcc can not be pulled up to Vccon), the IC can
startup in the condition given by equation(8).
In some cases, such as when the load current of power supply
is changed rapidly, you may want to prolong the hold time of
the power supply output by means of maintaining Vcc over the
off threshold.
For this purpose, connect diode D
4
and electrolytic capacitor
C
4
as shown in Fig. 23. This prolongs the hold time of the
power supply voltage Vcc regardless of the period from power-
on to startup.
Fig. 21 Startup circuit example(2)
Fig. 23 Startup circuit example(3)
Startup is impossible
Power ON
Power OFF
Vccon
Vccoff
Startup is impossible (dVcc/dt <1.8/Cs
just before Vcc reaches Vccon).
Icc>4mA
is necessary for startup at
Tj <100
°
C and dVcc/dt=0.
Fig. 22 Image of Vcc waveform when re-startup is impossible
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相關代理商/技術參數 |
參數描述 |
|---|---|
| FA5305AS | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:(367.00 k) |
| FA531 | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:FA531硅NPN型超高頻大功率晶體管 |
| FA5310 | 制造商:FUJI 制造商全稱:Fuji Electric 功能描述:Bipolar IC For Switching Power Supply Control |
| FA5310BP | 制造商:FUJI 制造商全稱:Fuji Electric 功能描述:Bipolar IC For Switching Power Supply Control |
| FA5310BP(S) | 制造商:未知廠家 制造商全稱:未知廠家 功能描述: |
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