LM2576/LM2576HV
Test Circuit and Layout Guidelines
As in any switching regulator, layout is very important. Rap-
idly switching currents associated with wiring inductance
generate voltage transients which can cause problems. For
minimal 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 con-
struction should be used for best results. When using the
Adjustable version, physically locate the programming resis-
tors near the regulator, to keep the sensitive feedback wiring
short.
Fixed Output Voltage Versions
01147607
C
IN
— 100 µF, 75V, Aluminum Electrolytic
C
OUT
— 1000 µF, 25V, Aluminum Electrolytic
D
1
— Schottky, MBR360
L
1
— 100 µH, Pulse Eng. PE-92108
R
1
— 2k, 0.1%
R
2
— 6.12k, 0.1%
Adjustable Output Voltage Version
01147608
where V
REF
= 1.23V, R1 between 1k and 5k.
FIGURE 2.
www.national.com
10
NSC [ NATIONAL SEMICONDUCTOR ]
