AAT1146 Datasheet, PDF (15/20 Pages) Advanced Analogic Technologies – Fast Transient 400mA Step-Down Converter

DATA SHEET
AAT1146
Fast Transient 400mA Step-Down Converter
Layout
The suggested PCB layout for the AAT1146 is shown in
Figures 2, 3, and 4. The following guidelines should be
used to help ensure a proper layout.
1. The input capacitor (C2) should connect as closely as
possible to V_IN (Pin 3) and PGND (Pins 6-8).
2. C1 and L1 should be connected as closely as possi-
ble. The connection of L1 to the LX pin should be as
short as possible.
3. The feedback trace or OUT pin (Pin 2) should be
separate from any power trace and connect as close-
ly as possible to the load point. Sensing along a
high-current load trace will degrade DC load regula-
tion. If external feedback resistors are used, they
should be placed as closely as possible to the OUT
pin (Pin 2) to minimize the length of the high imped-
ance feedback trace.
4. The resistance of the trace from the load return to
the PGND (Pins 6-8) should be kept to a minimum.
This will help to minimize any error in DC regulation
due to differences in the potential of the internal
signal ground and the power ground.
A high density, small footprint layout can be achieved
using an inexpensive, miniature, non-shielded, high DCR
inductor. An evaluation board is available with this induc-
tor and is shown in Figure 6. The total solution footprint
area is 40mm².
Figure 6: Minimum Footprint Evaluation Board
Using 2.0mm x 1.6mm x 0.95mm Inductor.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [e-mail] • www.skyworksinc.com
201985B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 18, 2013
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