GM7130_13 Datasheet, PDF (7/10 Pages) Gamma Microelectronics Inc. – 3A STEP DOWN VOLTAGE SWITCHING REGULATORS

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
VIN
VIN
Unregulatedd
DC Input
CIN
100μF
4
GM7130-x.x
Feedback
2
L1
100μH
3
5
Output
GND
ON/OFF
D1
VOUT
COUT
L
680μF ^O
A
D
Figure 1 Fixed Ouput Votlage Versions
CIN = 100μF, Aluminum Electrolytic
COUT = 680μF, 25V, Aluminum Electrolytic
D1 = Schottky
L1 = 100μH
1
VIN
VIN
Unregulatedd
DC Input
CIN
100μF
4
FB
GM7130-ADJ
3
GND
2
5
VOUT
ON/OFF
L1
100μH
D1
COUT
680μF
VOUT
R2 _L
O
A
R1 _D
Figure 2 Adjustable Ouput Votlage Versions
CIN = 100μF, Aluminum Electrolytic
COUT = 680μF, 25V, Aluminum Electrolytic
D1 = Schottky
L1 = 100μH
VOUT = VREF (1 + R2/R1)
where VREF = 1.23V and R1 is between 1K to 5K
7