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參數資料
| 型號： | LM2586T-5.0 |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | SIMPLE SWITCHER 3A Flyback Regulator with Shutdown |
| 中文描述： | 3 A SWITCHING REGULATOR, 200 kHz SWITCHING FREQ-MAX, PZFM7 |
| 封裝： | BENT STAGGERED, TO-220, 7 PIN |
| 文件頁數： | 24/28頁 |
| 文件大?。?/td> | 778K |
| 代理商： | LM2586T-5.0 |
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Application Hints
(Continued)
OUTPUT VOLTAGE LIMITATIONS
The maximum output voltage of a boost regulator is the
maximum switch voltage minus a diode drop. In a flyback
regulator, the maximum output voltage is determined by the
turns ratio, N, and the duty cycle, D, by the equation:
V
OUT
≈
N x V
IN
x D/(1 D)
The duty cycle of a flyback regulator is determined by the fol-
lowing equation:
Theoretically, the maximum output voltage can be as large
as desired— just keep increasing the turns ratio of the trans-
former. However, there exists some physical limitations that
prevent the turns ratio, and thus the output voltage, from in-
creasing to infinity. The physical limitations are capacitances
and inductances in the LM2586 switch, the output diode(s),
and the transformer— such as reverse recovery time of the
output diode (mentioned above).
NOISY INPUT LINE CONDITION
A small, low-pass RC filter should be used at the input pin of
the LM2586 if the input voltage has an unusually large
amount of transient noise, such as with an input switch that
bounces. The circuit in Figure 44 demonstrates the layout of
the filter, with the capacitor placed from the input pin to
ground and the resistor placed between the input supply and
the input pin. Note that the values of R
and C
shown in
the schematic are good enough for most applications, but
some readjusting might be required for a particular applica-
tion. If efficiency is a major concern, replace the resistor with
a small inductor (say 10 μH and rated at 200 mA).
STABILITY
All current-mode controlled regulators can suffer from an in-
stability, known as subharmonic oscillation, if they operate
with a duty cycle above 50%. To eliminate subharmonic os-
cillations, a minimum value of inductance is required to en-
sure stability for all boost and flyback regulators. The mini-
mum inductance is given by:
where V
is the switch saturation voltage and can be
found in the Characteristic Curves.
DS012516-63
FIGURE 44. Input Line Filter
DS012516-64
FIGURE 45. Circuit Board Layout
www.national.com
24
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相關代理商/技術參數 |
參數描述 |
|---|---|
| LM2586T-ADJ | 功能描述:直流/直流開關轉換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數量:2 最大工作溫度:+ 85 C 安裝風格:SMD/SMT |
| LM2586T-ADJ/NOPB | 功能描述:直流/直流開關轉換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數量:2 最大工作溫度:+ 85 C 安裝風格:SMD/SMT |
| LM2586T-ADJ/NOPB | 制造商:Texas Instruments 功能描述:DC/DC Converter (DC-DC) / Switching Regu |
| LM2587 | 制造商:Texas Instruments 功能描述: |
| LM2587EVAL | 功能描述:電源管理IC開發(fā)工具 EVAL BOARDFOR LM2587 RoHS:否 制造商:Maxim Integrated 產品:Evaluation Kits 類型:Battery Management 工具用于評估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V |
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