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| 型號(hào)： | LM2671N-12 |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | SIMPLE SWITCHER Power Converter High Efficiency 500mA Step-Down Voltage Regulator with Features |
| 中文描述： | 1.25 A SWITCHING REGULATOR, 275 kHz SWITCHING FREQ-MAX, PDIP8 |
| 封裝： | 0.300 INCH, PLASTIC, DIP-8 |
| 文件頁(yè)數(shù)： | 17/26頁(yè) |
| 文件大小： | 972K |
| 代理商： | LM2671N-12 |
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LM2671 Series Buck Regulator Design Procedure (Fixed Output)
(Continued)
LM2671 Series Buck Regulator Design Procedure (Adjustable Output)
PROCEDURE (Adjustable Output Voltage Version)
To simplify the buck regulator design procedure, National
Semiconductor is making available computer design software to
be used with the
SIMPLE SWITCHER
line of switching
regulators.
LM267X Made Simple
is available on
(version 6.0)
Windows
3.1, NT, or 95 operating systems.
Given:
V
OUT
= Regulated Output Voltage
V
IN
(max) = Maximum Input Voltage
I
LOAD
(max) = Maximum Load Current
F = Switching Frequency
(Fixed at a nominal 260 kHz).
1. Programming Output Voltage
(Selecting R
1
and R
2
, as
shown in
Figure 3
)
Use the following formula to select the appropriate resistor
values.
EXAMPLE (Adjustable Output Voltage Version)
Given:
V
OUT
= 20V
V
IN
(max) = 28V
I
LOAD
(max) = 500 mA
F = Switching Frequency
(Fixed at a nominal 260 kHz).
1. Programming Output Voltage
(Selecting R
1
and R
2
, as
shown in
Figure 3
)
Select R
1
to be 1 k
, 1%. Solve for R
2
.
where V
REF
= 1.21V
Select a value for R
1
between 240
and 1.5 k
. The lower
resistor values minimize noise pickup in the sensitive feedback
pin. (For the lowest temperature coefficient and the best stability
with time, use 1% metal film resistors.)
R
2
= 1 k
(16.53 1) = 15.53 k
, closest 1% value is 15.4 k
.
R
2
= 15.4 k
.
2. Inductor Selection (L1)
A.
Calculate the inductor Volt
microsecond constant E
T
(V
μs), from the following formula:
2. Inductor Selection (L1)
A.
Calculate the inductor Volt
microsecond constant (E
T),
where V
SAT
=internal switch saturation voltage=0.25V and
V
D
= diode forward voltage drop = 0.5V
AVX TPS
Recommended
Application Voltage
Voltage
Rating
+85C Rating
3.3
5
10
12
15
6.3
10
20
25
35
Sprague 594D
Recommended
Application Voltage
Voltage
Rating
+85C Rating
2.5
3.3
5
8
12
18
24
29
4
6.3
10
16
20
25
35
50
FIGURE 15. Recommended Application Voltage for AVX TPS and
Sprague 594D Tantalum Chip Capacitors Derated for 85C.
L
www.national.com
17
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM2671N-12/NOPB | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)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(fēng)格:SMD/SMT |
| LM2671N-3.3 | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)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(fēng)格:SMD/SMT |
| LM2671N-3.3/NOPB | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)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(fēng)格:SMD/SMT |
| LM2671N-5.0 | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)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(fēng)格:SMD/SMT |
| LM2671N-5.0/NOPB | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)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(fēng)格:SMD/SMT |
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