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參數資料
| 型號： | LM2670S-12 |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | SIMPLE SWITCHER High Efficiency 3A Step-Down Voltage Regulator with Sync |
| 中文描述： | 5.4 A SWITCHING REGULATOR, 280 kHz SWITCHING FREQ-MAX, PSSO7 |
| 封裝： | TO-263, 7 PIN |
| 文件頁數： | 12/23頁 |
| 文件大?。?/td> | 361K |
| 代理商： | LM2670S-12 |
Application Hints
(Continued)
For this example E
T is found to be:
Using Figure 6 the intersection of 27V
μS horizontally and
the 2A vertical line (I
max) indicates that L38 , a 68μH in-
ductor, should be used.
From Table 1, L38 in a surface mount component is available
from Pulse Engineering with part number PE-54038S.
Step 4:
Use Table 6 to determine an output capacitor. With a
14.8V output the 12.5 to 15V row is used and with a 68μH in-
ductor there are three surface mount output capacitor solu-
tions. Table 2 provides the actual capacitor characteristics
based on the C Code number. Any of the following choices
can be used:
1 x 33μF/20V AVX TPS (code C6)
1 x 47μF/20V Sprague 594 (code C8)
1 x 47μF/20V Kemet T495 (code C8)
Important Note:
When using the adjustable device in low
voltage applications (less than 3V output), if the nomograph,
Figure 6, selects an inductance of 22μH or less, Table 6 does
not provide an output capacitor solution. With these condi-
tions the number of output capacitors required for stable op-
eration becomes impractical. It is recommended to use ei-
ther a 33μH or 47μH inductor and the output capacitors from
Table 6.
Step 5:
An input capacitor for this example will require at
least a 35V WV rating with an rms current rating of 1A (1/2
Iout max). From Table 2 it can be seen that C12, a 33μF/35V
capacitor from Sprague, has the required voltage/current rat-
ing of the surface mount components.
Step 6:
From Table 5 a 3A Schottky diode must be selected.
For surface mount diodes with a margin of safety on the volt-
age rating one of five diodes can be used:
SK34
30BQ040
30WQ04F
MBRS340
MBRD340
Step 7:
A 0.01μF capacitor will be used for Cboost.
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相關代理商/技術參數 |
參數描述 |
|---|---|
| LM2670S-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 |
| LM2670S12NOPB | 制造商:National Semiconductor 功能描述:Conv DC-DC Single Step Down 8V to 40V 8-Pin(7+Tab) TO-263 Rail |
| LM2670S-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 |
| LM2670S-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 |
| LM2670S-3.3/NOPB | 制造商:Texas Instruments 功能描述:DC/DC Converter IC |
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