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參數(shù)資料
| 型號： | FS7M0880TU |
| 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： | 32 A SWITCHING REGULATOR, PSFM5 |
| 封裝： | TO-3P, 5 PIN |
| 文件頁數(shù)： | 7/12頁 |
| 文件大?。?/td> | 277K |
| 代理商： | FS7M0880TU |
FS7M0880
7
to the SPS V
CC
voltage. If V
CC
exceeds 24 V, the SPS IC
starts the protection circuit. Therefore, V
CC
should be
appropriately kept below 24V during normal operation.
OCP (Over Current Protection)
The FPS has various built-in, basic protection features. They
are the UVLO (Under Voltage Lock Out), OLP (Over Load
Protection) and OCP (Over Current Protection). However, if
a secondary side diode short or load short occur due to a
worst case condition, such as a maximum input voltage
putting a large strain on the device, another external
component may need to be added. By adding these
requirements in the FPS, superior reliability and
advantageous cost can be achieved.
When gate on signal of the SenseFet is received,
simultaneously the OCP block senses Ipeak through the
sense resistor for 1us. After the OCP block has turned on,
the voltage across the resistor is compared to the pre-set
voltage in the comparator, and, if it takes longer than 200ns
within the allowed comparison time of 1us, then the
comparator produces a high signal, which latches the OCP.
fig 4. shows the OCP latch waveform. When there is a diode
short/load short, the SPS turns on for the minimum turn-on
time. If the instantaneous current is of the form shown in fig
4., the OCP block opens a 1us window to compare the
voltage proportional to the current across the resistor with
the reference voltage and latches. Here, the 100ns delay
after the 200ns is the delay time to SenseFET gate off and is
generated from the comparison of the voltage across the
sense resistor.
Soft start operation
Normally, the SMPS output voltage increases from start up
with a fixed time constant. This is due to the capacitive
component of the load. At start up, therefore, the feedback
signal applied to the PWM comparator's inverting input
reaches its maximum value (1V), This is because the
feedback loop is effectively open. Also at this time, the
drain current is at its peak value (I
peak
) and maximum
allowable power is being delivered to the secondary load.
With that said, note that when the SMPS pushes maximum
power to the secondary side for this initial fixed time, the
entire
circuit is seriously stressed. Use of a soft start function
avoids such stresses. Figure 6 shows how to implement a
soft start for a Fairchild Power Switch(FPS). At turn on, the
soft start capacitor on pin 5 of the Fairchild Power
Switch(FPS) starts to charge through the 1mA current
source. When the voltage across C
S
reaches 3V, diode D
S
turns off. No more current flows to it from the 1mA current
source. Cs then continues to charge to 5V through the 20k
resistor.
Note that when the voltage across C
S
exceeds 3V, The voltage
at the comparator’s inverting terminal no longer follows the
voltage across C
S
. Instead, it follows the output voltage
feedback signal. In shutdown or protection circuit operation,
capacitor C
S
is discharged, to enable it to charge from 0V at
restart.
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Fiqure 5. OCP Function & Block
Figure 6. Soft Start Circuit.
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PDF描述 |
|---|---|
| FS7M0880YDTU | Fairchild Power Switch(FPS) |
| FS7SM-12 | HIGH-SPEED SWITCHING USE |
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| FS7SM-16A | HIGH-SPEED SWITCHING USE |
| FS7SM-18 | AML34 Series Rocker Switch, DPST, 2 position, Silver Contacts, 0.187 in x 0.02 in (Solder or Quick-Connect), Non-Lighted, Rectangle, Snap-in Panel |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| FS7M0880TU | 制造商:Fairchild Semiconductor Corporation 功能描述:Power Supply IC |
| FS7M0880YDTU | 功能描述:電流型 PWM 控制器 8a/800V Power Switch 70kHz RoHS:否 制造商:Texas Instruments 開關頻率:27 KHz 上升時間: 下降時間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風格:SMD/SMT 封裝 / 箱體:TSSOP-14 |
| FS7SM12 | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:TRANSISTOR | MOSFET | N-CHANNEL | 600V V(BR)DSS | 7A I(D) | TO-247VAR |
| FS7SM-12 | 制造商:RENESAS 制造商全稱:Renesas Technology Corp 功能描述:MITSUBISHI Nch POWER MOSFET |
| FS7SM-14 | 制造商:POWEREX 制造商全稱:Powerex Power Semiconductors 功能描述:Nch POWER MOSFET HIGH-SPEED SWITCHING USE |
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