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參數(shù)資料
| 型號(hào)： | FS8S0765RCBYDTU |
| 廠商： | FAIRCHILD SEMICONDUCTOR CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | Fairchild Power Switch(FPS) |
| 中文描述： | 28 A SWITCHING REGULATOR, 150 kHz SWITCHING FREQ-MAX, PZFM5 |
| 封裝： | TO-220, 5 PIN |
| 文件頁數(shù)： | 12/20頁 |
| 文件大?。?/td> | 1847K |
| 代理商： | FS8S0765RCBYDTU |
FS8S0765RCB
12
3.2 Over Load Protection (OLP)
: When the load current
exceeds a pre-set level for longer than pre-determined time,
protection circuit should be activated in order to protect the
SMPS. Because of the pulse-by-pulse current limit
capability, the maximum peak current through the SMPS is
limited, and therefore the maximum input power is restricted
with a given input voltage. If the output consumes beyond
this maximum power, the output voltage together with pri-
mary side regulation voltage decrease below the set voltage.
This reduces the current through primary side regulation
transistor, which increases feedback voltage (Vfb). If Vfb
exceeds 2.7V, D1 is blocked and the 2uA current source
starts to charge Cfb slowly compared to when the 0.9mA
current source charges Cfb. In this condition, Vfb continues
increasing until it reaches 7.5V, and the switching operation
is terminated at that time as shown in figure 6. The delay
time for shutdown is the time required to charge Cfb from
2.7V to 7.5V with 2uA.
Figure 5. The waveforms at the OLP and auto restart
Figure 6. Over load protection
3.3 Over Voltage Protection (OVP) :
In case of malfunc-
tion in the primary side feedback circuit, or feedback loop
open caused by a defect of solder, the current through pri-
mary side control transistor becomes almost zero. Then, Vfb
climbs up in a similar manner to the over load situation, forc-
ing the preset maximum current to be supplied to the second-
ary side until the over load protection is activated. Because
energy more than required is provided to the output, the out-
put voltage may exceed the rated voltage before the over
load protection is activated, resulting in the breakdown of the
devices in the secondary side. In order to prevent this situa-
tion, an over voltage protection (OVP) circuit is employed.
When the Vcc voltage touches 37V, the OVP block is acti-
vated.
3.4 Thermal Shutdown (TSD) :
The SenseFET and the
control IC are built in one package. This makes it easy for
the control IC to detect the heat generation from the
SenseFET. When the temperature exceeds approximately
160
°
C
, the thermal shutdown is activated.
4. Soft Start
: Figure 7 shows the soft start circuit. During
the initial start up, the 0.9 mA current source leaks out
through Css and Rss. As Css is charged, the leakage current
decreases. Therefore, by choosing much bigger Css than
Cfb, it is possible to increase the feedback voltage slowly
forcing the SenseFET current to increase slowly. After Css
reaches its steady state value, D3 is blocked and the soft
switching circuit is decoupled from the feedback circuit. If
the value of Css is too large, there is possibility that Vfb
increases to 7.5V activating the over load protection during
soft start time. In order to avoid this situation, it is recom-
mended that the value of Css should not exceed 100 times of
Cfb.
Figure 7. The circuit for the soft start
5. Synchronization :
In order to reduce the effect of switch-
ing noise on the screen, the SMPS for monitor synchronizes
its switching frequency to an external signal, typically the
horizontal sync flyback signal. The switching frequency of
the FPS can vary from 20 kHz to 150 kHz according to the
time
time
V
V
1
5V
9V
Vcc
Vds
Over load protection
Auto restart
time
V
7.5V
Vfb
22V
V
FB
t
2.7V
7.5V
Over load protection
T
1
2
= Cfb*(7.5-2.7)/I
delay
T
1
T
2
GATE
DRIVER
OSC
4
Voffset
2.5R
R
PWM
COMP.
2uA
0.9mA
Cfb
D
S
5
Vref
FS8S0765RCB
50K
Css
Rss
D3
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PDF描述 |
|---|---|
| FS8S0965RCB | Fairchild Power Switch(FPS) |
| FS8S0965RCBTU | Fairchild Power Switch(FPS) |
| FS8S0965RCBYDTU | Fairchild Power Switch(FPS) |
| FSA1156 | Low RON Low Voltage SPST Analog Switch |
| FSA1156L6X | Low RON Low Voltage SPST Analog Switch |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| FS8S0765RCTU | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:SMPS Controller |
| FS8S0765RCYDTU | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:SMPS Controller |
| FS8S0965RCB | 制造商:FAIRCHILD 制造商全稱:Fairchild Semiconductor 功能描述:Fairchild Power Switch(FPS) |
| FS8S0965RCBSYDT | 功能描述:電源開關(guān) IC - 配電 FPS FOR CRT 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(shí)間（最大值）:400 us 關(guān)閉時(shí)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(fēng)格:SMD/SMT 封裝 / 箱體:SOT-23-5 |
| FS8S0965RCBTU | 制造商:FAIRCHILD 制造商全稱:Fairchild Semiconductor 功能描述:Fairchild Power Switch(FPS) |
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