GM7109-3.3PS8R GAMMA [Gamma Microelectronics Inc.], GM7109-3.3PS8R Datasheet - Page 6

• Manufacturer Part Number: GM7109-3.3PS8R
• Description: 150KHz, 2A STEP DOWN VOLTAGE SWITCHING REGULATORS
• Manufacturer: GAMMA [Gamma Microelectronics Inc.]

6
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 GM7109, to keep the sensitive feedback wiring short.
Unregulatedd
DC Input
Unregulatedd
V
IN
DC Input
V
IN
C
100µF
IN
Figure 2 Adjustable Ouput Votlage Versions
V
1
IN
C
100µF
Figure 1 Fixed Ouput Votlage Versions
IN
V
IN
1
C
C
D1 = Schottky, 5A/40V
L1 = 68µH
C
C
D1 = Schottky, 5A/40V
L1 = 68µH
V
5 ~ 8
GND
OUT
IN
OUT
IN
OUT
GM7109-A
= 470µF, Aluminum Electrolytic
= 470µF, Aluminum Electrolytic
= V
= 220µF, 25V, Aluminum Electrolytic
= 220µF, 25V, Aluminum Electrolytic
GM7109-x.x
5 ~ 8
GND
REF
(1 + R2/R1)
4
SD
4
SD
3
FB
2
V
OUT
2
V
3
FB
OUT
D1
150KHz, 2A STEP DOWN VOLTAGE
100µH
L1
D1
100µH
L1
SWITCHING REGULATORS
C
680µF
OUT
C
680µF
OUT
GM7109
R2
R1
V
V
OUT
OUT
L
O
A
D
L
O
A
D