AME
1.5MHz, 600mA
Synchronous Buck Converter
AME5258
VIN
VIN
VOUT
3V
VOUT
2.2mH
2.2mH
3.3V to 5.5V
3.6V to 5.5V
3.3V
IN
IN
SW
FB
SW
FB
22pF
COUT
22pF
COUT
AME5258
GND
10mF
AME5258
GND
10mF
CER
CER
EN
EN
960K
887K
COUT
4.7mF
CER
COUT
4.7mF
CER
240K
196K
Figure 8: 3V Step-Down Regulator
PC Board Layout Checklist
Figure 9: 3.3V Step-Down Regulator
When laying out the printed circuit board, the following checklist should be used to ensure proper operation of the
AME5258. These items are also illustrated graphically in Figures 10 and Figures 11 . Check the following in your layout:
1. The power traces, consisting of the GND trace, the SW trace and the VIN trace should be kept short, direct and wide.
2. Does the VFB pin connect directly to the feedback resistors? The resistive divider R1/R2 must be connected between
the (+) plate of COUT and ground.
3. Does the (+) plate of CIN connect to VIN as closely as possible? This capacitor provides the AC current to the internal
power MOSFETs.
4. Keep the switching node, SW, away from the sensitive VFB node.
5. Keep the (-) plates of C and COUT as close as possible.
IN
L1
L1
VIN
VIN
VOUT
VOUT
IN
IN
SW
FB
SW
+
CFWD
+
COUT
-
AME5258
COUT
AME5258
-
EN
EN
VOUT
R2
R1
+
+
GND
CIN
GND
CIN
-
-
Figure 10: AME5258 Adjustable Voltage
Regulator Layout Diagram
Figure 11: AME5258 Fixed Voltage
Regulator Layout Diagram
Rev.A.05
11
AMETHERM [ AMETHERM CIRCUIT PROTECTION THERMISTORS ]
