LTC3631 Datasheet, PDF (16/22 Pages) Linear Technology – High Effi ciency, High Voltage 100mA Synchronous Step-Down Converter

LTC3631
APPLICATIONS INFORMATION
PC Board Layout Checklist
Example Layout
When laying out the printed circuit board, the following
checklist should be used to ensure proper operation of
the LTC3631. Check the following in your layout:
1. Large switched currents flow in the power switches and
input capacitor. The loop formed by these components
should be as small as possible. A ground plane is
recommended to minimize ground impedance.
L1
V_IN
V_IN
SW
V_OUT
LTC3631
RUN
R1
C_IN
HYST
V_FB
C_OUT
SS
I_SET
C_SS
GND
R2
R_SET
3631 F09a
2. Connect the (+) terminal of the input capacitor, C_IN, as
close as possible to the V_IN pin. This capacitor provides
the AC current into the internal power MOSFETs.
3. Keep the switching node, SW, away from all sensitive ^VIN
small signal nodes. The rapid transitions on the switching
node can couple to high impedance nodes, in particular
V_FB, and create increased output ripple.
4. Flood all unused area on all layers with copper. Flooding
with copper will reduce the temperature rise of power
components. You can connect the copper areas to any
DC net (V_IN, V_OUT, GND or any other DC rail in your
system).
L1
C_IN
C_OUT
V_OUT
R_SET C_SS
GND
VIAS TO GROUND PLANE
VIAS TO INPUT SUPPLY (V_IN)
OUTLINE OF LOCAL GROUND PLANE
R1
R2
3631fb
16