LM2673SX-5.0/NOPB National Semiconductor, LM2673SX-5.0/NOPB Datasheet - Page 14
![no-image](/images/manufacturer_photos/0/4/469/national_semiconductor_sml.jpg)
LM2673SX-5.0/NOPB
Manufacturer Part Number
LM2673SX-5.0/NOPB
Description
IC REG SW 5V 3A STP DN TO-263-7
Manufacturer
National Semiconductor
Series
SIMPLE SWITCHER®r
Type
Step-Down (Buck)r
Datasheet
1.LM2673SD-12NOPB.pdf
(26 pages)
Specifications of LM2673SX-5.0/NOPB
Internal Switch(s)
Yes
Synchronous Rectifier
No
Number Of Outputs
1
Voltage - Output
5V
Current - Output
3A
Frequency - Switching
260kHz
Voltage - Input
8 ~ 40 V
Operating Temperature
-40°C ~ 125°C
Mounting Type
Surface Mount
Package / Case
D²Pak, TO-263 (7 leads + tab)
For Use With
LM2673-5.0EVAL - EVALUATION BOARD FOR LM2673-5.0
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Power - Output
-
Other names
*LM2673SX-5.0
*LM2673SX-5.0/NOPB
LM2673SX-5.0
*LM2673SX-5.0/NOPB
LM2673SX-5.0
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Company:
Part Number:
LM2673SX-5.0/NOPB
Manufacturer:
NS
Quantity:
7 000
www.national.com
Using Figure 6, the intersection of 27V•μS horizontally and
the 2A vertical line (I
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
inductor 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
operation 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 ca-
pacitor from Sprague, has the required voltage/current rating
of the surface mount components.
load
max) indicates that L38 , a 68μH in-
14
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.
The softstart pin will be left open circuited.
Step 8: Determine a value for R
current limit of at least 2A plus 50% or 3A.
Use a value of 12.4KΩ.
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 Ap-
plication Note AN-1187.
ADJ
to provide a peak switch