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參數(shù)資料
| 型號： | LM2672M-ADJ |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | SIMPLE SWITCHER Power Converter High Efficiency 1A Step-Down Voltage Regulator with Features |
| 中文描述： | 2.2 A SWITCHING REGULATOR, 275 kHz SWITCHING FREQ-MAX, PDSO8 |
| 封裝： | 0.150 INCH, PLASTIC, SO-8 |
| 文件頁數(shù)： | 18/25頁 |
| 文件大小： | 895K |
| 代理商： | LM2672M-ADJ |
LM2672 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
version 1.0 is available on
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) = 1A
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
B.
Use the E
T value from the previous formula and match it
with the E
T number on the vertical axis of the Inductor Value
Selection Guide shown in
Figure 7
.
C.
On the horizontal axis, select the maximum load current.
D.
Identify the inductance region intersected by the E
T value
and the Maximum Load Current value. Each region is identified
by an inductance value and an inductor code (LXX).
B.
E
T = 21.6 (V
μs)
C.
I
LOAD
(max) = 1A
D.
From the inductor value selection guide shown in
Figure 7
,
the inductance region intersected by the 21.6 (V
μs) horizontal
line and the 1A vertical line is 68 μH, and the inductor code is
L30.
E.
From the table in
Figure 8
, locate line L30, and select an
inductor part number from the list of manufacturers’ part
numbers.
E.
Select an appropriate inductor from the four manufacturer’s
part numbers listed in
Figure 8
. For information on the different
types of inductors, see the inductor selection in the fixed output
voltage design procedure.
3. Output Capacitor SeIection (C
OUT
)
A.
Select an output capacitor from the capacitor code selection
guide in
Figure 16
. Using the inductance value found in the
inductor selection guide, step 1, locate the appropriate capacitor
code corresponding to the desired output voltage.
3. Output Capacitor SeIection (C
OUT
)
A.
Use the appropriate row of the capacitor code selection
guide, in
Figure 16
. For this example, use the 15–20V row. The
capacitor code corresponding to an inductance of 68 μH is C20.
L
www.national.com
18
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| LM2672M-ADJ | 制造商:Texas Instruments 功能描述:SWITCHING REG 1A ADJ 2672 SOIC8 |
| LM2672M-ADJ/NOPB | 功能描述:直流/直流開關轉換器 HIGH EFF 1A STEP- DOWN VLTG REG 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 |
| LM2672M-ADJ/NOPB | 制造商:Texas Instruments 功能描述:DC/DC Converter (DC-DC) / Switching Regu |
| LM2672MX-12 | 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 |
| LM2672MX-12/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 |
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