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TEST CIRCUIT AND LAYOUT GUIDELINES
Careful layout is important with any switching regulator. Rapidly switching currents associated with wiring
inductance generate voltage transients which can cause problems. To minimize inductance and ground loops,
the lengths of the leads indicated by heavy lines in Figure 1 below should be kept as short as possible. Single-
point grounding (as indicated in Figure 1) or ground plane construction should be used for best results. When
using the Adjustable version, place the programming resistors as close as possible to the GM7130, to keep the
sensitive feedback wiring short.
Figure 1(a). Fixed Output Voltage Versions
V
IN
Unregulated
DC Input
+V
IN
1
+
C
IN
GND 3
5
2
Output
4
Feedback
L1
D1
C
OUT
V
OUT
GM 7130-
FIXED OUTPUT
+
ON/OFF
L
O
A
D
C
- 100 µF, 75V, Aluminum Electrolytic
IN
C
- 680 µF, 25V, Aluminum Electrolytic
OUT
D1 - Schottky, MBR360
L1 - 100 µH, 3L Electronic Corp. TC-101M-3.0A-6826
R1 - 2k, 0.1%
R2 - 6.12k, 0.1%
100 µH
680 µF
100 µF
GM7130
7
GM7130-ADJ
7V - 40V
Unregulated
DC Input
+V
IN
1
C
IN
GND 3
5
2
4
D1
L1
R2
R1
Output
Feedback
V
=5.0V
OUT
C
OUT
+
+
L
O
A
D
Figure 1(b). Adjustable Output Voltage Versions
V
= V
( 1 +
)
OUT
REF
R2 = R1 (
-1)
where V
= 1.23V, R1 between 1k and 5k.
REF
R2
R1
V
OUT
V
REF
680 µF
100 µF
100 µH
ON/ OFF
MBR360
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