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参数资料
| 型号： | LM2672LD-5.0/NOPB |
| 厂商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分类： | 稳压器 |
| 英文描述： | 2.2 A SWITCHING REGULATOR, 275 kHz SWITCHING FREQ-MAX, PDSO16 |
| 封装： | LLP-16 |
| 文件页数： | 9/26页 |
| 文件大小： | 626K |
| 代理商： | LM2672LD-5.0/NOPB |
LM2672 Series Buck Regulator Design Procedure (Adjustable Output)
PROCEDURE (Adjustable Output Voltage Version)
EXAMPLE (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 6.0 is available on Windows 3.1,
NT, or 95 operating systems.
Given:
V
OUT = Regulated Output Voltage
V
OUT = 20V
V
IN(max) = Maximum Input Voltage
V
IN(max) = 28V
I
LOAD(max) = Maximum Load Current
I
LOAD(max) = 1A
F = Switching Frequency (Fixed at a nominal 260 kHz).
1. Programming Output Voltage
(Selecting R
1 and R2, as shown
in Figure 3)
Use the following formula to select the appropriate resistor values.
1. Programming Output Voltage
(Selecting R
1 and R2, as shown
in Figure 3)
Select R
1 to be 1 kΩ, 1%. Solve for R2.
where V
REF = 1.21V
Select a value for R
1 between 240Ω and 1.5 kΩ. 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 kΩ (16.53 1) = 15.53 kΩ, closest 1% value is 15.4 kΩ.
R
2 = 15.4 kΩ.
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.
B.
E T = 21.6 (V
μs)
C.
On the horizontal axis, select the maximum load current.
C.
I
LOAD(max) = 1A
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).
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.
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.
E.
From the table in Figure 8, locate line L30, and select an inductor
part number from the list of manufacturers' part numbers.
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.
17
www.national.com
LM2672
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LM2672LD-ADJ | 功能描述:直流/直流开关转换器 RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| LM2672LD-ADJ/NOPB | 功能描述:直流/直流开关转换器 RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| LM2672LDX-12 | 制造商:未知厂家 制造商全称:未知厂家 功能描述: |
| LM2672LDX-3.3 | 制造商:NSC 制造商全称:National Semiconductor 功能描述:SIMPLE SWITCHER㈢ Power Converter High Efficiency 1A Step-Down Voltage Regulator with Features |
| LM2672LDX-5.0 | 制造商:未知厂家 制造商全称:未知厂家 功能描述: |
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