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參數資料
| 型號： | FA3647P |
| 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, PDIP8 |
| 封裝： | DIP-8 |
| 文件頁數： | 9/21頁 |
| 文件大小： | 406K |
| 代理商： | FA3647P |
FA3641P(N), FA3647P(N)
66
Fig. 7 CS pin waveform
Fig. 6 CS pin circuit
4. CS pin circuit
As shown in Figure 6, capacitor Cs is connected to the CS pin.
The CS pin voltage varies depending on the charging voltage of
this capacitor Cs. When the power is turned on, the constant
current source (6.5
μ
A) begins to charge capacitor. Accordingly,
the CS pin voltage rises as shown in Figure 7. The CS pin
voltage is connected to the PWM comparator, which is
characterized to make output based on the lowest of input
voltages. The device enters soft-start mode while the CS pin
voltage is between 1.0V and 2.4V. During normal operation, the
CS pin is clamped at 4.0V by internal zener diode.
If the output voltage drops due to an overload and the FB
voltage rises to 3V or more, the clamp voltage 4.0V is canceled
and the CS pin voltage rises to 9.5V. The CS pin is also
connected to latch comparator C2. If the CS pin voltage rises
to 8.5V or more, comparator C2 toggles to turn off the 5V REF
circuit, thereby shutting the output down. Since the CS pin is
also connected to comparator C1, the 5V REF circuit can be
turned off to shut the output down by dropping the CS pin
voltage below 0.68V. In this way, comparator C1 can be used
for output on-off control.
As explained above, the CS pin can be used for soft-start,
overload output shutdown, and output on-off control by varying
the voltage.
Further details on the above three major functions of the CS pin
are given below.
4.1 Soft start function
Figure 8 shows the soft start circuit. Figure 9 is a soft-start
operation timing chart. The CS pin is connected to capacitor
Cs. When the power is turned on, the constant current source
(6.5
μ
A) begins to charge the capacitor. As shown in the timing
chart, the CS pin voltage rises slowly in accordance with the
capacitor Cs charging current. The CS pin is also connected to
the IC internal PWM comparator, which has such
characteristics that the voltage is determined to output on the
basis of the lowest of input voltages. The comparator output
pulse slowly widens to cause a soft start as shown in the timing
chart.
The soft start period can be approximately estimated by the
period t
S
, from the time the IC is activated to the time the output
pulse width widens to 30%. The period is given by the following
equation:
ts [ms] 250 Cs ...................................................... (3)
Cs : Soft start capacitor [
μ
F]
Fig. 8 Soft-sart circuit
Fig. 9 Soft-sart timing chart
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PDF描述 |
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| 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 |
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相關代理商/技術參數 |
參數描述 |
|---|---|
| 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 |
| FA-365 14.31818MHZ 50PPM 16PF | 制造商:Epson Toyocom Corporation 功能描述:XTAL FA-365 14.31818MHZ 50PPM 16PF |
| FA-365 16.0000MB-G3 | 功能描述:CRYSTAL 16.0000MHZ 20PF SMD RoHS:是 類別:晶體和振蕩器 >> 晶體 系列:FA-365 標準包裝:1 系列:ABLS2 類型:MHz 晶體 頻率:3.579545MHz 頻率穩定性:±30ppm 頻率公差:±30ppm 負載電容:18pF ESR（等效串聯電阻）:180 歐姆 工作模式:基諧 工作溫度:-40°C ~ 85°C 額定值:- 安裝類型:表面貼裝 封裝/外殼:HC49/US 尺寸/尺寸:0.449" L x 0.185" W（11.40mm x 4.70mm） 高度:0.130"（3.30mm） 包裝:剪切帶 (CT) 產品目錄頁面:1683 (CN2011-ZH PDF) 其它名稱:535-9855-1 |
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