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參數資料
| 型號： | LM2599T-12 |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 穩壓器 |
| 英文描述： | SIMPLE SWITCHER Power Converter 150 kHz 3A Step-Down Voltage Regulator, with Features |
| 中文描述： | 7.5 A SWITCHING REGULATOR, 173 kHz SWITCHING FREQ-MAX, PZFM7 |
| 封裝： | TO-220, 7 PIN |
| 文件頁數： | 25/31頁 |
| 文件大小： | 812K |
| 代理商： | LM2599T-12 |
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Application Information
(Continued)
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 compo-
nents 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 mate-
rial 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 25 is a standard buck regulator
with 20V in, 12V out, 1Aload, and using a 0.068 μF Soft-start
capacitor. The photo in Figure 23 Figure 24 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.
This reduction in start up current is useful in situations where
the input power source is limited in the amount of current it
can deliver. In some applications Soft-start can be used to
replace undervoltage lockout or delayed startup functions.
If a very slow output voltage ramp is desired, the Soft-start
capacitor can be made much larger. Many seconds or even
minutes are possible.
If only the shutdown feature is needed, the Soft-start capaci-
tor can be eliminated.
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 22. Junction Temperature Rise, TO-263
DS012582-40
FIGURE 23. Output Voltage, Input Current,
at Start-Up, WITH Soft-start
DS012582-41
FIGURE 24. Output Voltage, Input Current,
at Start-Up, WITHOUT Soft-start
L
www.national.com
25
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相關代理商/技術參數 |
參數描述 |
|---|---|
| LM2599T12 | 制造商:Texas Instruments 功能描述:SWITCHING REG 3A 12V 2599 TO2207 |
| LM2599T-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 輸出端數量:2 最大工作溫度:+ 85 C 安裝風格:SMD/SMT |
| LM2599T-3.3 | 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 輸出端數量:2 最大工作溫度:+ 85 C 安裝風格:SMD/SMT |
| LM2599T-3.3/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 輸出端數量:2 最大工作溫度:+ 85 C 安裝風格:SMD/SMT |
| LM2599T-5.0 | 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 輸出端數量:2 最大工作溫度:+ 85 C 安裝風格:SMD/SMT |
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