AAT2514_08 Datasheet, PDF (13/14 Pages) Advanced Analogic Technologies – Dual Channel 600mA Step-Down Converter

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PRODUCT DATASHEET
AAT2514
Dual Channel 600mA Step-Down Converter
Layout Guidance
Figure 1 is the schematic for a typical application. When
laying out the PC board, the following layout guidelines
should be followed to ensure proper operation of the
AAT2514:
1. Exposed pad must be reliably soldered to GND. The
exposed thermal pad should be connected to the
board ground plane and GND. The ground plane
should include a large exposed copper pad under the
package for thermal dissipation.
2. The power traces, including the GND trace, the LX1/
LX2 traces, and the VIN trace should be kept short,
direct and wide to allow large current flow. The L1/2
connection to the LX1/2 pins should be as short as
possible. Use several VIA pads when routing between
layers.
3. The input capacitor (C1) should connect as closely as
possible to IN and GND to get good power filtering.
4. Keep the switching nodes, LX1/LX2, away from the
sensitive FB1/FB2 nodes.
5. The feedback traces or FB pins should be separate
from any power trace and connected as closely as
possible to the load point. Sensing along a high-
current load trace will degrade DC load regulation.
The feedback resistors should be placed as close as
possible to the FB pins to minimize the length of the
high impedance feedback trace.
6. The output capacitors C2/C3 and L1/L2 should be
connected as close as possible and there should not
be any signal lines under the inductor.
7. The resistance of the trace from the load return to
GND should be kept to a minimum. This will help to
minimize any error in DC regulation due to differ-
ences in the potential of the internal signal ground
and the power ground.
Figure 2 shows an example of a layout with 4 layers. The
2nd and 3rd layers are Internal GND Plane.
a: Top Layer
b: Bottom Layer
Figure 2: AAT2514 Typical Application Circuit Layout.
2514.2008.02.1.1
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