LM2576BU Micrel Inc, LM2576BU Datasheet - Page 8

• Manufacturer Part Number: LM2576BU
• Description: IC REG BUCK 3A ADJ TO-263-5
• Manufacturer: Micrel Inc
• Type: Step-Down (Buck)r

Specifications of LM2576BU

• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: 1.23 ~ 37 V
• Current - Output: 3A
• Frequency - Switching: 42kHz ~ 63kHz
• Voltage - Input: 4 ~ 40 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: D²Pak, TO-263 (5 leads + tab)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Power - Output: -

LM2576
Test Circuits and Layout Guidelines
Block Diagrams
M9999-082605-B
FEED-
BACK
V IN
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.
1
4
Note: Pin numbers are for the TO-220 package
UNREGULATED
UNREGULATED
REFERENCE
BAND-GAP
DC INPUT
DC INPUT
Note: Pin numbers are for TO-220 Package
1.23V
7V - 40V
7V - 40V
3.1k
1.0k
+
-
FIXED GAIN
ERROR AMP
OSCILLATOR
52 kHz
Fixed Regulator
+
+
100 µF
100 µF
+
C
C
-
IN
IN
COMPARATOR
REGULATOR
INTERNAL
RESET
+V
+V
IN
IN
1
1
GND
GND
LM2575-5.0
SHUTDOWN
THERMAL
3
3
LM2575
ON/OFF
ON/OFF
ON/OFF
DRIVER
CURRENT
LIMIT
5
5
3 AMP
SWITCH
4
2
4
2
FEEDBACK
FEEDBACK
OUTPUT
OUTPUT
5
2
3
D1
MBR360
D1
11DQ06
ON/OFF
OUTPUT
GND
330 µH
330 µH
Figure 1.
L1
L1
FEED-
BACK
8
V IN
+
+
1
4
C
470µF
C
220µF
OUT
OUT
REFERENCE
BAND-GAP
1.23V
V
5.00V
OUT
L
O
A
D
+
-
FIXED GAIN
ERROR AMP
OSCILLATOR
R1
R2
52 kHz
V
5.00V
OUT
L
O
A
D
Adjustable Regulator
+
-
COMPARATOR
REGULATOR
INTERNAL
RESET
C
C
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.)
C
C
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.)
SHUTDOWN
IN
OUT
IN
OUT
THERMAL
— 100µF, 75V Aluminum Electrolytic
— 100µF, 75V Aluminum Electrolytic
— 470µF, 15V Aluminum Electrolytic
— 330µF, 15V Aluminum Electrolytic
ON/OFF
DRIVER
CURRENT
LIMIT
3 AMP
SWITCH
August 2005
5
2
3
Micrel, Inc.
ON/OFF
OUTPUT
GND