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参数资料
| 型号： | LM2574-ADJMDC |
| 厂商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分类： | 稳压器 |
| 英文描述： | 1.8 A SWITCHING REGULATOR, 63 kHz SWITCHING FREQ-MAX, UUC |
| 封装： | DIE |
| 文件页数： | 6/33页 |
| 文件大小： | 814K |
| 代理商： | LM2574-ADJMDC |
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LM2574 Series Buck Regulator Design Procedure (Continued)
PROCEDURE (Adjustable Output Voltage Versions)
EXAMPLE (Adjustable Output Voltage Versions)
Given:
V
OUT = Regulated Output Voltage
V
IN(Max) = Maximum Input Voltage
I
LOAD(Max) = Maximum Load Current
F = Switching Frequency
(Fixed at 52 kHz)
Given:
V
OUT = 24V
V
IN(Max) = 40V
I
LOAD(Max) = 0.4A
F = 52 kHz
1. Programming Output Voltage
(Selecting R1 and R2, as
shown in Figure 2)
Use the following formula to select the appropriate resistor
values.
R
1 can be between 1k and 5k. (For best temperature coeffi-
cient and stability with time, use 1% metal film resistors)
1. Programming Output Voltage
(Selecting R1 and R2)
R
2 = 1k (19.511) = 18.51k, closest 1% value is 18.7k
2. Inductor Selection (L1)
A. Calculate the inductor Volt
microsecond constant,
E
T(V s), from the following formula:
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 8.
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, and note the in-
ductor value for that region.
E. Select an appropriate inductor from the table shown in
Fig-
ure 3. Part numbers are listed for three inductor manufactur-
ers. The inductor chosen must be rated for operation at the
LM2574 switching frequency (52 kHz) and for a current rating
of 1.5 x I
LOAD. For additional inductor information, see the in-
ductor section in the application hints section of this data
sheet.
2. Inductor Selection (L1)
A. Calculate E
T(V s)
B. E
T = 185 V s
C. I
LOAD(Max) = 0.4A
D. Inductance Region = 1000
E. Inductor Value = 1000 H
Choose from Pulse Engineer-
ing Part #PE-52631, or Renco Part #RL-1283-1000.
DS011394-16
FIGURE 8. LM2574HV-ADJ Inductor Selection Guide
www.national.com
14
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LM2574BN | 功能描述:IC REG BUCK ADJ 0.5A 8DIP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:20 系列:SIMPLE SWITCHER® 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:12V 输入电压:4 V ~ 60 V PWM 型:电压模式 频率 - 开关:52kHz 电流 - 输出:1A 同步整流器:无 工作温度:-40°C ~ 125°C 安装类型:通孔 封装/外壳:16-DIP（0.300"，7.62mm） 包装:管件 供应商设备封装:16-DIP 其它名称:*LM2575HVN-12LM2575HVN-12 |
| LM2574BWM | 制造商:Rochester Electronics LLC 功能描述:- Bulk 制造商:RF Micro Devices Inc 功能描述: 制造商:Micrel Inc 功能描述: |
| LM2574DW | 制造商:ONSEMI 制造商全称:ON Semiconductor 功能描述:0.5 A, Adjustable Output Voltage, Step-Down Switching Regulator |
| LM2574DW-ADJ | 功能描述:直流/直流开关调节器 500mA Adj. Step Down RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5 |
| LM2574DW-ADJR2 | 功能描述:直流/直流开关调节器 500mA Adj. Step Down RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5 |
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