LM2575, NCV2575
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24
THE LM2575−ADJ STEP−DOWN VOLTAGE REGULATOR WITH 8.0 V @ 1.0 A OUTPUT POWER
CAPABILITY. TYPICAL APPLICATION WITH THROUGH−HOLE PC BOARD LAYOUT
C1 − 100 mF, 50 V, Aluminium Electrolytic
C2 − 330 mF, 16 V, Aluminium Electrolytic
C3 − 100 mF, 16 V, Aluminium Electrolytic
D1 − 1.0 A, 40 V, Schottky Rectifier, 1N5819
L1 − 330 mH, Tech 39: 77 458 BV, Toroid Core, Through−Hole, Pin 3 = Start, Pin 7 = Finish
L2 − 25 mH, TDK: SFT52501, Toroid Core, Through−Hole
R1 − 1.8 k
R2 − 10 k
Figure 38. Schematic Diagram of the 8.0 V @ 1.0 V Step−Down Converter Using the LM2575−Adj
(An additional LC filter is included to achieve low output ripple voltage)
Figure 39. PC Board Component Side Figure 40. PC Board Copper Side
V
ref
= 1.23 V
R1 is between 1.0 k and 5.0 k
D1
1N5819
L1
330 mH
Output
2
R2
10 k
R1
1.8 k
L2
25 mH
Regulated
Output Filtered
V
out2
= 8.0 V @1.0 A
Unregulated
DC Input
C2
330 mF
/16 V
C3
100 mF
/16 V
C1
100 mF
/50 V
LM2575−Adj
1
53ON
/OFFGND
+V
in
+V
in
= +10 V to + 40 V
4 Feedback
Regulated
Output Unfiltered
V
out1
= 8.0 V @1.0 A
V
out
+ V
ref
)
ǒ
1 )
R2
R1
Ǔ
+V
out1
+V
in
GND
in
C1
L1
C2
D1
J1
U1 LM2575
L2
C3
+V
out2
R2 R1
GND
out
NOTE: Not to scale. NOTE: Not to scale.
References
• National Semiconductor LM2575 Data Sheet and Application Note
• National Semiconductor LM2595 Data Sheet and Application Note
• Marty Brown “Practical Switching Power Supply Design”, Academic Press, Inc., San Diego 1990
• Ray Ridley “High Frequency Magnetics Design”, Ridley Engineering, Inc. 1995
