Datasheet

LT3514
20
3514fa
For more information www.linear.com/LT3514
PCB Layout
For proper operation and minimum EMI, care must be taken
during printed circuit board layout. Figure 8 shows the
recommended component placement with trace, ground
plane, and via locations for the QFN package.
Note that large, switched currents flow in the LT3514’s
V
IN
, SW and DA pins, the catch diodes (D1, D3, D4) and
the input capacitors (C5, C6). The loop formed by these
components should be as small as possible and tied to
system ground in only one place. These components, along
with the inductors (L1, L3, L4, L5) and output capacitors
(C1, C3, C4, C7), should be placed on the same side of
the circuit board, and their connections should be made
on that layer. Place a local, unbroken ground plane below
these components, and tie this ground plane to system
ground at one location (ideally at the ground terminal
of the output capacitors). For the QFN package ground
APPLICATIONS INFORMATION
Figure 8
VIA TO LOCAL GROUND PLANE
OUTLINE OF LOCAL GROUND PLANE
3514 F08
L5
D3
D1
D4
SW5
VIN
VIN
GND
GND
GND
GND
GND GND GND
RT/SYNC
FB4
SKY
SW3
SW4
C4
SW1
OUT3
OUT4
OUT1
GND
GND
C3
GND
C1
C5
C7
C8
L3
L1
L4
C6
RUN/SS4 RUN/SS1 RUN/SS3
EN/UVLO
R9
PG
NC
NC
NC
NC
R2 R5
FB1
R3 R6
FB3
R1 R7
VIA TO VIN
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