LM2672
Test Circuit and Layout Guidelines
(Continued)
01293423
C
IN
- 22 µF, 50V Tantalum, Sprague “199D Series”
C
OUT
- 47 µF, 25V Tantalum, Sprague “595D Series”
D1 - 3.3A, 50V Schottky Rectifier, IR 30WQ05F
L1 - 68 µH Sumida #RCR110D-680L
R1 - 1.5 kΩ, 1%
C
B
- 0.01 µF, 50V Ceramic
For a 5V output, select R2 to be 4.75 kΩ, 1%
where V
REF
= 1.21V
Use a 1% resistor for best stability.
FIGURE 3. Standard Test Circuits and Layout Guides
Adjustable Output Voltage Versions
LM2672 Series Buck Regulator
Design Procedure (Fixed Output)
PROCEDURE (Fixed Output Voltage Version)
To simplify the buck regulator design procedure, National
Semiconductor is making available computer design software to
be used with the
SIMPLE SWITCHER
line of switching
regulators.
LM267X Made Simple
version 1.0 is available on
Windows
®
3.1, NT, or 95 operating systems.
Given:
V
OUT
= Regulated Output Voltage (3.3V, 5V, or 12V)
V
IN
(max) = Maximum DC Input Voltage
I
LOAD
(max) = Maximum Load Current
Given:
V
OUT
= 5V
V
IN
(max) = 12V
I
LOAD
(max) = 1A
EXAMPLE (Fixed Output Voltage Version)
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