GM2574 Datasheet, PDF (6/8 Pages) Gamma Microelectronics Inc. – 1.5A STEP DOWN VOLTAGE SWITCHING REGULATORS

GM2574
1.5A 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 GM2574, to keep the sensitive feedback wiring short.
1
V_IN
V_IN
Unregulatedd
DC Input
C_IN
100µF
3
FB
GM2574-x.x
2
5~8
4
V_OUT
GND
SD
L1
100µH
D1
V_OUT
C_OUT
L
680µF ^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
GM2574-A
5~8
4
GND
SD
3
FB
2
V_OUT
L1
100µH
D1
C_OUT
680µF
V_OUT
R2 _L
O
A
R1 _D
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
6