- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄30747 > LM2673LD-12 (NATIONAL SEMICONDUCTOR CORP) 5.4 A SWITCHING REGULATOR, 280 kHz SWITCHING FREQ-MAX, PDSO14 PDF資料下載
參數(shù)資料
| 型號： | LM2673LD-12 |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 5.4 A SWITCHING REGULATOR, 280 kHz SWITCHING FREQ-MAX, PDSO14 |
| 封裝： | LLP-14 |
| 文件頁數(shù)： | 5/25頁 |
| 文件大?。?/td> | 433K |
| 代理商： | LM2673LD-12 |
Application Hints (Continued)
Iload max = 2A
Step 2: Select an LM2673S-ADJ. To set the output voltage
to 14.9V two resistors need to be chosen (R1 and R2 in
Figure 2). For the adjustable device the output voltage is set
by the following relationship:
Where V
FB is the feedback voltage of typically 1.21V.
A recommended value to use for R1 is 1K. In this example
then R2 is determined to be:
R2 = 11.23K
The closest standard 1% tolerance value to use is 11.3K
This will set the nominal output voltage to 14.88V which is
within 0.5% of the target value.
Step 3: To use the nomograph for the adjustable device,
6,
requires
a
calculation
of
the
inductor
Volt
microsecond constant (ET expressed in VS) from
the following formula:
where V
SAT is the voltage drop across the internal power
switch which is R
ds(ON) times Iload. In this example this would
be typically 0.15
x 2A or 0.3V and V
D is the voltage drop
across the forward bisased Schottky diode, typically 0.5V.
The switching frequency of 260KHz is the nominal value to
use to estimate the ON time of the switch during which
energy is stored in the inductor.
For this example E
T is found to be:
Using Figure 6, the intersection of 27V
S horizontally and
the 2A vertical line (I
load max) indicates that L38 , a 68H
inductor, 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 68H
inductor there are three surface mount output capacitor so-
lutions. Table 2 provides the actual capacitor characteristics
based on the C Code number. Any of the following choices
can be used:
1 x 33F/20V AVX TPS (code C6)
1 x 47F/20V Sprague 594 (code C8)
1 x 47F/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 22H or less, Table 6 does
not provide an output capacitor solution. With these condi-
tions the number of output capacitors required for stable
operation becomes impractical. It is recommended to use
either a 33H or 47H 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 33F/35V
capacitor from Sprague, has the required voltage/current
rating of the surface mount components.
Step 6: From Table5a3A Schottky diode must be selected.
For surface mount diodes with a margin of safety on the
voltage rating one of five diodes can be used:
SK34
30BQ040
30WQ04F
MBRS340
MBRD340
Step 7: A 0.01F capacitor will be used for Cboost.
The softstart pin will be left open circuited.
Step 8: Determine a value for R
ADJ to provide a peak switch
current limit of at least 2A plus 50% or 3A.
Use a value of 12.4K
.
LLP Package Devices
The LM2673 is offered in the 14 lead LLP surface mount
package to allow for a significantly decreased footprint with
equivalent power dissipation compared to the TO-263. For
details on mounting and soldering specifications, refer to
Application Note AN-1187.
LM2673
www.national.com
13
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LM2673LDX-5.0 | 5.4 A SWITCHING REGULATOR, 280 kHz SWITCHING FREQ-MAX, PDSO14 |
| LM2676LD-5.0 | 5.4 A SWITCHING REGULATOR, 280 kHz SWITCHING FREQ-MAX, DSO14 |
| LM2676LD-3.3 | 5.4 A SWITCHING REGULATOR, 280 kHz SWITCHING FREQ-MAX, DSO14 |
| LM2676LDX-12 | 5.4 A SWITCHING REGULATOR, 280 kHz SWITCHING FREQ-MAX, DSO14 |
| LM2682MWC | SWITCHED CAPACITOR CONVERTER, 15 kHz SWITCHING FREQ-MAX, UUC |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM2673LD3.3 | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
| LM2673LD-3.3 | 制造商:Rochester Electronics LLC 功能描述:3A STEP DOWN SIMP SWITCH 260KH - Bulk |
| LM2673LD-5.0 | 制造商:Rochester Electronics LLC 功能描述:3A STEP DOWN SIMP SWITCH 260KH - Bulk |
| LM2673LD-ADJ | 制造商:Rochester Electronics LLC 功能描述:3A STEP DOWN SIMP SWITCH 260KH - Bulk |
| LM2673S-12 | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 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 |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。