LTC3545/LTC3545-1
16
35451fb
PC Board Layout Checklist
When laying out the printed circuit board, the following
checklist should be used to ensure proper operation of
the LTC3545/LTC3545-1. These items are also illustrated
graphically in Figures 3 and 4. Figure 3 shows the power
path components and traces. In this fi gure the feedback
networks are not shown since they reside on the bottom
side of the board. Check the following in your layout:
1. The power traces consisting of the PGND trace, the SW
trace, the PV
IN
trace, the V
IN
and GNDA traces, should
be kept short direct and wide.
2. Does each of the V
FBx
pins connect directly to the
respective feedback resistors? The resistive dividers
must be connected between the (+) plate of the cor-
responding output fi lter capacitor (e.g. C2) and GNDA.
If the circuit being powered is at such a distance from
the part where voltage drops along circuit traces are
large, consider a Kelvin connection from the powered
circuit back to the resistive dividers.
3. Keep C1 and C5 as close to the part as possible.
4. Keep the switching nodes (SWx) away from the sensi-
tive V
FBx
nodes.
5. Keep the ground connected plates of the input and
output capacitors as close as possible.
6. Care should be taken to provide enough space between
unshielded inductors in order to minimize any trans-
former coupling.
APPLICATIONS INFORMATION
Figure 3. Layout Diagram
L3
L2L1
C2
C5
C1
C4
C3
V
OUT3
(VIA TO FEEDBACK
NETWORK)
(VIA TO FEEDBACK
NETWORK)
(VIA TO FEEDBACK
NETWORK)
V
OUT2
PGNDPV
IN
SW3
SW2SW1
V
OUT1
V
IN
GNDA
3545 F03
