參數(shù)資料
型號: LM2586SX-ADJ
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, PSSO7
封裝: TO-263, 7 PIN
文件頁數(shù): 24/28頁
文件大小: 778K
代理商: LM2586SX-ADJ
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(shù)
參數(shù)描述
LM2586SX-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(shù)量:2 最大工作溫度:+ 85 C 安裝風格:SMD/SMT
LM2586T-12 制造商:Texas Instruments 功能描述:
LM2586T-12/NOPB 功能描述:IC REG MULTI CONFIG 12V TO220-7 RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關穩(wěn)壓器 系列:SIMPLE SWITCHER® 產品培訓模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標準包裝:1 系列:- 類型:降壓(降壓) 輸出類型:固定 輸出數(shù):1 輸出電壓:3.3V 輸入電壓:4.5 V ~ 24 V PWM 型:- 頻率 - 開關:- 電流 - 輸出:125mA 同步整流器:無 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:SOT-23-6 包裝:Digi-Reel® 供應商設備封裝:SOT-6 其它名稱:MAX1836EUT33#TG16DKR
LM2586T-3.3 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(shù)量:2 最大工作溫度:+ 85 C 安裝風格:SMD/SMT
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