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參數(shù)資料
| 型號： | LM2596S-ADJ |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | SIMPLE SWITCHER Power Converter 150 kHz 3A Step-Down Voltage Regulator |
| 中文描述： | 7.5 A SWITCHING REGULATOR, 173 kHz SWITCHING FREQ-MAX, PSSO5 |
| 封裝： | TO-263, SMT-5 |
| 文件頁數(shù)： | 24/31頁 |
| 文件大小： | 736K |
| 代理商： | LM2596S-ADJ |
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Application Information
(Continued)
THERMAL CONSIDERATIONS
The LM2596 is available in two packages, a 5-pin TO-220
(T) and a 5-pin surface mount TO-263 (S).
The TO-220 package needs a heat sink under most condi-
tions. The size of the heatsink depends on the input voltage,
the output voltage, the load current and the ambient tem-
perature. The curves in Figure 19 show the LM2596T junc-
tion temperature rises above ambient temperature for a 3A
load and different input and output voltages. The data for
these curves was taken with the LM2596T (TO-220 pack-
age) operating as a buck switching regulator in an ambient
temperature of 25C (still air). These temperature rise num-
bers are all approximate and there are many factors that can
affect these temperatures. Higher ambient temperatures re-
quire more heat sinking.
The TO-263 surface mount package tab is designed to be
soldered to the copper on a printed circuit board. The copper
and the board are the heat sink for this package and the
other heat producing components, such as the catch diode
and inductor. The PC board copper area that the package is
soldered to should be at least 0.4 in
2
, and ideally should
have 2 or more square inches of 2 oz. (0.0028) in) copper.
Additional copper area improves the thermal characteristics,
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 20 show the LM2596S (TO-263
package) junction temperature rise above ambient tempera-
ture with a 2Aload 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 2Aare
used, double sided or multilayer PC boards with large cop-
per 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.
01258334
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 19. Junction Temperature Rise, TO-220
01258335
Circuit Data for Temperature Rise Curve
TO-263 Package (S)
Capacitors
Surface mount tantalum, molded “D” size
Inductor
Surface mount, Pulse Engineering, 68 μH
Diode
Surface mount, 5A 40V, Schottky
PC board
9 square inches single sided 2 oz. copper
(0.0028")
FIGURE 20. Junction Temperature Rise, TO-263
L
www.national.com
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM2596S-ADJ NOPB | 制造商:Texas Instruments 功能描述:Bulk |
| LM2596S-ADJ | 制造商:Texas Instruments 功能描述:IC SWITCHING REG 3A ADJ SMD 2596 |
| LM2596S-ADJ/HAPB | 制造商:Texas Instruments 功能描述: |
| LM2596S-ADJ/NOPB | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 150 KHZ 3A STEP-DOWN VLTG REG 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 |
| LM2596S-ADJ/NOPB | 制造商:Texas Instruments 功能描述:DC/DC Converter (DC-DC) / Switching Regu |
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