LM2576
Micrel, Inc.
Test Circuits and Layout Guidelines
FEEDBACK
+V
IN
1
7V - 40V
UNREGULATED
DC INPUT
+
100 µF
C
IN
GND 3
ON/OFF 5
2
4
LM2575
OUTPUT
L1
330 µH
D1
MBR360
V
OUT
5.00V
+
C
OUT
470µF
R2
R1
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.)
FEEDBACK
+V
IN
1
7V - 40V
UNREGULATED
DC INPUT
+
100 µF
C
IN
GND 3
ON/OFF 5
2
4
LM2575-5.0
OUTPUT
L1
330 µH
D1
11DQ06
V
OUT
5.00V
+
C
OUT
220µF
L
O
A
D
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.)
Note:
Pin numbers are for TO-220 Package
Figure 1.
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.
Block Diagrams
V IN
FEED-
BACK
1
4
3.1k
INTERNAL
REGULATOR
ON/OFF
5
ON/OFF
V IN
1
INTERNAL
REGULATOR
ON/OFF
5
ON/OFF
FIXED GAIN
ERROR AMP
FIXED GAIN
ERROR AMP
COMPARATOR
3 AMP
SWITCH
FEED-
BACK
+
1.0k
4
+
-
+
-
COMPARATOR
3 AMP
SWITCH
-
+
-
DRIVER
DRIVER
2
1.23V
BAND-GAP
REFERENCE
OUTPUT
1.23V
BAND-GAP
REFERENCE
2
OUTPUT
52 kHz
OSCILLATOR
RESET
THERMAL
SHUTDOWN
CURRENT
LIMIT
3
GND
52 kHz
OSCILLATOR
RESET
THERMAL
SHUTDOWN
CURRENT
LIMIT
3
GND
Note: Pin numbers are for the TO-220 package
Fixed Regulator
Adjustable Regulator
M9999-082605-B
8
August 2005
MICREL [ MICREL SEMICONDUCTOR ]
