參數(shù)資料
型號: LM2577T-12
廠商: NATIONAL SEMICONDUCTOR CORP
元件分類: 穩(wěn)壓器
英文描述: Explosion-Proof Limit Switches Series EX: Side Rotary; 1NC 1NO SPDT Snap Action; 0.5 in - 14NPT conduit
中文描述: 6 A SWITCHING REGULATOR, 62 kHz SWITCHING FREQ-MAX, PSFM5
封裝: TO-220, 5 PIN
文件頁數(shù): 17/27頁
文件大?。?/td> 889K
代理商: LM2577T-12
Application Hints
(Continued)
3. Output Voltage Selection (R1 and R2)
This section is for applications using the LM1577-ADJ/
LM2577-ADJ. Skip this section if the LM1577-12/LM2577-12
or LM1577-15/LM2577-15 is being used.
With the LM1577-ADJ/LM2577-ADJ, the output voltage is
given by
V
OUT
= 1.23V (1 + R1/R2)
Resistors R1 and R2 divide the output down so it can be
compared
with
the
LM1577-ADJ/LM2577-ADJ
1.23V reference. For a given desired output voltage V
OUT
,
select R1 and R2 so that
internal
4. Input Capacitor Selection (C
IN
)
The switching action in the step-up regulator causes a trian-
gular ripple current to be drawn from the supply source. This
in turn causes noise to appear on the supply voltage. For
proper operation of the LM1577, the input voltage should be
decoupled. Bypassing the Input Voltage pin directly to
ground with a good quality, low ESR, 0.1 μF capacitor (leads
as short as possible) is normally sufficient.
If the LM1577 is located far from the supply source filter ca-
pacitors, an additional large electrolytic capacitor (e.g.
47 μF) is often required.
5. Diode Selection (D)
The switching diode used in the boost regulator must with-
stand a reverse voltage equal to the circuit output voltage,
and must conduct the peak output current of the LM2577. A
suitable diode must have a minimum reverse breakdown
voltage greater than the circuit output voltage, and should be
rated for average and peak current greater than I
and I
. Schottky barrier diodes are often favored for use
in switching regulators. Their low forward voltage drop allows
higher regulator efficiency than if a (less expensive) fast re-
covery diode was used. See Figure 12 for recommended
part numbers and voltage ratings of 1A and 3A diodes.
BOOST REGULATOR CIRCUIT EXAMPLE
By adding a few external components (as shown in Figure
13), the LM2577 can be used to produce a regulated output
voltage that is greater than the applied input voltage. Typical
performance of this regulator is shown in Figure 14 and Fig-
ure 15 The switching waveforms observed during the opera-
tion of this circuit are shown in Figure 16
Cornell Dublier
— Types 239, 250, 251, UFT,
300, or 350
P.O. Box 128, Pickens, SC 29671
(803) 878-6311
Nichicon
— Types PF, PX, or PZ
927 East Parkway,
Schaumburg, IL 60173
(708) 843-7500
Sprague
— Types 672D, 673D, or 674D
Box 1, Sprague Road,
Lansing, NC 28643
(919) 384-2551
United Chemi-Con
— Types LX, SXF, or SXJ
9801 West Higgins Road,
Rosemont, IL 60018
(708) 696-2000
FIGURE 11. Aluminum Electrolytic Capacitors
Recommended for Switching Regulators
V
OUT
(max)
20V
Schottky
Fast Recovery
1A
1A
3A
3A
1N5817
MBR120P
1N5818
MBR130P
11DQ03
1N5819
MBR140P
11DQ04
MBR150
11DQ05
1N5820
MBR320P
1N5821
MBR330P
31DQ03
1N5822
MBR340P
31DQ04
MBR350
31DQ05
30V
40V
1N4933
MUR105
1N4934
HER102
MUR110
10DL1
50V
MR851
30DL1
MR831
HER302
100V
FIGURE 12. Diode Selection Chart
www.national.com
17
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相關代理商/技術參數(shù)
參數(shù)描述
LM2577T12 制造商:Texas Instruments 功能描述:SWITCHING REG 3A 12V 2577 TO2205
LM2577T-12/LB03 功能描述:直流/直流開關轉(zhuǎn)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
LM2577T-12/LF03 功能描述:直流/直流開關轉(zhuǎn)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
LM2577T-12/NOPB 功能描述:直流/直流開關轉(zhuǎn)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
LM2577T-12/NOPB 制造商:Texas Instruments 功能描述:Voltage Regulator IC