M9999-082605-B 8 August 2005
LM2576 Micrel, Inc.
LM2575
+
100 µF
+V
IN
1
3GND 5ON/OFF
2
OUTPUT
4
FEEDBACK
L1
330 µH
+
D1
MBR360
C
OUT
470µF
R2
R1
V
OUT
5.00V
7V - 40V
UNREGULATED
DC INPUT
C
IN
L
O
A
D
C
IN
— 100µF, 75V Aluminum Electrolytic
C
OUT
— 470µF, 15V Aluminum Electrolytic
D1 — Schottky, MBR360
L1 — 330µH, 415-0926 (AIE)
R1 — 1k, 0.01%
R2 — 3.065k, 0.01%
5-pin TO-220 socket—2936 (Loranger Mfg. Co.)
4-pin TO-3 socket—8112-AG7 (Augat Inc.)
LM2575-5.0
+
100 µF
+V
IN
1
3GND 5ON/OFF
2
OUTPUT
4
FEEDBACK
L1
330 µH
+
D1
11DQ06
C
OUT
220µF
V
OUT
5.00V
Note: Pin numbers are for TO-220 Package
7V - 40V
UNREGULATED
DC INPUT
C
IN
C
IN
— 100µF, 75V Aluminum Electrolytic
C
OUT
— 330µF, 15V Aluminum Electrolytic
D1 — Schottky, 11DQ06
L1 — 100µH, 415-0926 (AIE)
5-pin TO-220 socket—2936 (Loranger Mfg. Co.)
4-pin TO-3 socket—8112-AG7 (Augat Inc.)
L
O
A
D
ON/OFF
COMPARATOR
FIXED GAIN
ERROR AMP
3 AMP
SWITCH
OUTPUT
DRIVER
+
-
+
-
V
IN
FEED-
BACK
1.23V
BAND-GAP
REFERENCE
52 kHz
OSCILLATOR
RESET
THERMAL
SHUTDOWN
CURRENT
LIMIT
5
2
3
1
Note: Pin numbers are for the TO-220 package
INTERNAL
REGULATOR
ON/OFF
GND
ON/OFF
COMPARATOR
FIXED GAIN
ERROR AMP
3 AMP
SWITCH
OUTPUT
DRIVER
+
-
+
-
V
IN
FEED-
BACK
1.23V
BAND-GAP
REFERENCE
52 kHz
OSCILLATOR
RESET
THERMAL
SHUTDOWN
CURRENT
LIMIT
5
2
3
1
4
INTERNAL
REGULATOR
ON/OFF
GND
3.1k
1.0k
4
Block Diagrams
As in any switching regulator, layout is very important. Rapidly switching currents associated with wiring inductance generate voltage transients
which can cause problems. For minimal stray inductance and ground loops, the length of the leads indicated by heavy lines should be kept as
short as possible. Single-point grounding (as indicated) or ground plane construction should be used for best results.
Fixed Regulator Adjustable Regulator
Test Circuits and Layout Guidelines
Figure 1.
