Step-Up/Step-Down DC-DC Converter for 1-Cell Lithium-Ion Batteries
Layout And Grounding Considerations
High frequency switching and large peak currents means
PCB design for DC-DC converters requires careful consid-
eration. A general rule is to place the DC-DC converter cir-
cuitry well away from any sensitive RF or analog compo-
nents. The layout of the DC-DC converters and its external
components are also based on some simple rules to mini-
mize EMI and output voltage ripple.
Layout
1. Place all power components, ILC6360, inductor, input
capacitor and output capacitor as close together as possible.
2. Keep the output capacitor as close to the ILC6360 as
possible with very short traces to the V
OUT
and GND pins.
Typically it should be within 0.25 inches or 6mm.
3. Keep the traces for the power components wide, typically >
50mil or 1.25mm.
4. Place the external networks for LBI and V
FB
close to the
ILC6360, but away from the power components as far
as possible.
Grounding
1. Use a star grounding system with separate traces for the
power ground and the low power signals such as LBI/SD
and V
FB
. The star should radiate from where the power
supply enters the PCB.
2. On multilayer boards use component side copper for
grounding around the ILC6360 and connect back to a
quiet ground plane using vias.
C
IN
100µF
ILC6360CIR-ADJ
L1
1
L
X
V
IN
LBI/SD
SYNC
V
OUT
GND
LBO
V
FB
8
7
6
5
R2
C
OUT
10µF 100µF
V
OUT
V
IN
15µH
2
3
+
+
R1
R3
Load
ON/OFF
4
R4
Local "Quiet" Ground
Power Ground
Impala Linear Corporation
ILC6360 1.1
(408) 574-3939
www.impalalinear.com
Jan 1999
9
IMPALA [ Impala Linear Corporation ]
