Datasheet

10004233
FIGURE 14. RMS Current Ratings for Low ESR Electrolytic Capacitors (Typical)
AVX TPS
Recommended
Application Voltage
Voltage
Rating
+85°C Rating
3.3 6.3
5 10
10 20
12 25
15 35
Sprague 594D
Recommended
Application Voltage
Voltage
Rating
+85°C Rating
2.5 4
3.3 6.3
Recommended
Application Voltage
Voltage
Rating
+85°C Rating
5 10
8 16
12 20
18 25
24 35
29 50
FIGURE 15. Recommended Application Voltage for AVX TPS and
Sprague 594D Tantalum Chip Capacitors Derated for 85°C.
LM2671 Series Buck Regulator Design Procedure (Adjustable Output)
PROCEDURE (Adjustable Output Voltage Version) EXAMPLE (Adjustable 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 is available on (version 6.0) Windows 3.1,
NT, or 95 operating systems.
Given: Given:
V
OUT
= Regulated Output Voltage V
OUT
= 20V
V
IN
(max) = Maximum Input Voltage V
IN
(max) = 28V
I
LOAD
(max) = Maximum Load Current I
LOAD
(max) = 500 mA
F = Switching Frequency (Fixed at a nominal 260 kHz). F = Switching Frequency (Fixed at a nominal 260 kHz).
1. Programming Output Voltage (Selecting R
1
and R
2
, as shown
in Figure 3)
Use the following formula to select the appropriate resistor values.
1. Programming Output Voltage (Selecting R
1
and R
2
, as shown
in Figure 3)
Select R
1
to be 1 kΩ, 1%. Solve for R
2
.
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LM2671