GM7130
3A STEP DOWN VOLTAGE SWITCHING
REGULATORS
Test Circuit and Layout Guidelines
Careful layout is important with any switching regulators. 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&2 below should be
kept as short as possible. Single point grounding (as indicated or ground plane construction should
be used for best results. When using the Adjustable version, place the programming resistors as
close as possible to GM2576, to keep the sensitive feedback wiring short.
1
V
IN
V
IN
Unregulatedd
DC Input
C
IN
100µF
4
Feedback
GM7130-x.x
3
GND
5
ON/OFF
2
Output
L1
100µH
D1
C
OUT
680µF
V
OUT
L
O
A
D
Figure 1 Fixed Ouput Votlage Versions
C
IN
= 100µF, Aluminum Electrolytic
C
OUT
= 680µF, 25V, Aluminum Electrolytic
D1 = Schottky
L1 = 100µH
1
V
IN
V
IN
Unregulatedd
DC Input
C
IN
100µF
4
FB
GM7130-ADJ
3
GND
2
V
OUT
L1
100µH
V
OUT
R2
L
O
A
D
5
ON/OFF
D1
C
OUT
680µF
R1
GM7130
V1.11
Figure 2 Adjustable Ouput Votlage Versions
C
IN
= 100µF, Aluminum Electrolytic
C
OUT
= 680µF, 25V, Aluminum Electrolytic
D1 = Schottky
L1 = 100µH
V
OUT
= V
REF
(1 + R2/R1)
where V
REF
= 1.23V and R1 is between 1K to 5K
8
GAMMA [ GAMMA MICROELECTRONICS INC. ]
