LM2576-12 MOTOROLA [Motorola, Inc], LM2576-12 Datasheet - Page 8

• Manufacturer Part Number: LM2576-12
• Description: Easy Switcher 3.0A Step-Down Voltage Regulator
• Manufacturer: MOTOROLA [Motorola, Inc]

circuit board is very important. Rapidly switching currents
associated with wiring inductance, stray capacitance and
parasitic inductance of the printed circuit board traces can
generate voltage transients which can generate
electromagnetic interferences (EMI) and affect the desired
operation. As indicated in the Figure 15, to minimize
inductance and ground loops, the length of the leads
indicated by heavy lines should be kept as short as possible.
ground plane construction should be used.
8
As in any switching regulator, the layout of the printed
For best results, single–point grounding (as indicated) or
7.0 V – 40 V
Unregulated
DC Input
7.0 V – 40 V
Unregulated
DC Input
C in
100 F
V in
C in
100 F
1
V in
3
1
Adjustable
C in
C out –
D1
L1
R1
R2
Adjustable Output Voltage Versions
Gnd
LM2576
3
Figure 15. Typical Test Circuit
Fixed Output Voltage Versions
PCB LAYOUT GUIDELINES
Fixed Output
–
–
–
–
–
Gnd
LM2576
100 F, 75 V, Aluminium Electrolytic
1000 F, 25 V, Aluminium Electrolytic
Schottky, MBR360
100 H, Pulse Eng. PE–92108
2.0 k, 0.1%
6.12 k, 0.1%
5
V out
R2
Where V ref = 1.23 V, R1
between 1.0 k and 5.0 k
ON/OFF
+
5
+
LM2576
2
R1
4
Output
Feedback
V
ON/OFF
ref
V out
V
2
ref
4
Output
Feedback
1.0
(emitter of the internal switch) of the LM2576 should be kept
to a minimum in order to minimize coupling to sensitive
circuitry.
important to keep the sensitive feedback wiring short. To
assure this, physically locate the programming resistors near
to the regulator, when using the adjustable version of the
LM2576 regulator.
– 1.0
)
100 H
D1
MBR360
On the other hand, the PCB area connected to the Pin 2
Another sensitive part of the circuit is the feedback. It is
R2
R1
L1
100 H
D1
MBR360
L1
C out
1000 F
MOTOROLA ANALOG IC DEVICE DATA
C out
1000 F
R2
R1
Load
V out
5,000 V
Load
V out