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参数资料
| 型号： | LM2599-ADJMWC |
| 厂商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分类： | 稳压器 |
| 英文描述： | 7.5 A SWITCHING REGULATOR, 173 kHz SWITCHING FREQ-MAX, UUC |
| 封装： | WAFER |
| 文件页数： | 18/36页 |
| 文件大小： | 897K |
| 代理商： | LM2599-ADJMWC |
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Application Information (Continued)
but with copper areas greater than approximately 6 in
2, only
small improvements in heat dissipation are realized. If fur-
ther thermal improvements are needed, double sided, mul-
tilayer pc-board with large copper areas and/or airflow are
recommended.
The curves shown in
Figure 23 show the LM2599S (TO-263
package) junction temperature rise above ambient tempera-
ture with a 2A load for various input and output voltages. This
data was taken with the circuit operating as a buck switching
regulator with all components mounted on a pc board to
simulate the junction temperature under actual operating
conditions. This curve can be used for a quick check for the
approximate junction temperature for various conditions, but
be aware that there are many factors that can affect the
junction temperature. When load currents higher than 2A are
used, double sided or multilayer pc-boards with large copper
areas and/or airflow might be needed, especially for high
ambient temperatures and high output voltages.
For the best thermal performance, wide copper traces and
generous amounts of printed circuit board copper should be
used in the board layout. (One exception to this is the output
(switch) pin, which should not have large areas of copper.)
Large areas of copper provide the best transfer of heat
(lower thermal resistance) to the surrounding air, and moving
air lowers the thermal resistance even further.
Package thermal resistance and junction temperature rise
numbers are all approximate, and there are many factors
that will affect these numbers. Some of these factors include
board size, shape, thickness, position, location, and even
board temperature. Other factors are, trace width, total
printed circuit copper area, copper thickness, single- or
double-sided, multilayer board and the amount of solder on
the board. The effectiveness of the pc board to dissipate
heat also depends on the size, quantity and spacing of other
components on the board, as well as whether the surround-
ing air is still or moving. Furthermore, some of these com-
ponents such as the catch diode will add heat to the pc
board and the heat can vary as the input voltage changes.
For the inductor, depending on the physical size, type of core
material and the DC resistance, it could either act as a heat
sink taking heat away from the board, or it could add heat to
the board.
SHUTDOWN /SOFT-START
The circuit shown in
Figure 26 is a standard buck regulator
with 20V in, 12V out, 1A load, and using a 0.068 F Soft-start
capacitor. The photo in
Figure 24 Figure 25 show the effects
of Soft-start on the output voltage, the input current, with,
and without a Soft-start capacitor. The reduced input current
required at startup is very evident when comparing the two
photos. The Soft-start feature reduces the startup current
from 2.6A down to 650 mA, and delays and slows down the
output voltage rise time.
DS012582-38
Circuit Data for Temperature Rise Curve TO-220
Package (T)
Capacitors
Through hole electrolytic
Inductor
Through hole Renco
Diode
Through hole, 5A 40V, Schottky
PC board
3 square inches single sided 2 oz. copper
(0.0028")
FIGURE 22. Junction Temperature Rise, TO-220
DS012582-39
Circuit Data for Temperature Rise Curve TO-263
Package (S)
Capacitors
Surface mount tantalum, molded “D” size
Inductor
Surface mount, Pulse engineering, 68 H
Diode
Surface mount, 5A 40V, Schottky
PC board
9 square inches single sided 2 oz. copper
(0.0028")
FIGURE 23. Junction Temperature Rise, TO-263
LM2599
www.national.com
25
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相关代理商/技术参数 |
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| LM2599S-12 | 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 |
| LM2599S-12/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 |
| LM2599S-3.3 | 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 |
| LM2599S-3.3/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 |
| LM2599S-5.0 | 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 |
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