AAT1171 Datasheet, PDF (17/22 Pages) Advanced Analogic Technologies – 600mA Voltage-Scaling Step-Down Converter for RF Power Amplifiers with Bypass Switch

DATA SHEET
AAT1171
600mA Voltage-Scaling Step-Down Converter
for RF Power Amplifiers with Bypass Switch
WLCSP Package Light Sensitivity
The electrical performance of the WLCSP package can be
adversely affected by exposing the device to certain light
sources such as direct sunlight or a halogen lamp whose
wavelengths are red and infra-reds. However, fluores-
cent lighting has very little effect on the electrical per-
formance of the WLCSP package.
Layout
The suggested PCB layout for the AAT1171 is shown in
Figures 4 and 5. The following guidelines should be used
to ensure a proper layout.
1. The input capacitor (C1) should connect as closely
as possible to VIN (Pin 10) and PGND (Pin 11).
2. C2 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 PCB trace connected to VOUT (Pins 2 and 3) is
tied to the bypass path, as well as the feedback path
for the control loop. In bypass mode, the full load
current is delivered directly from the battery input;
therefore, this trace should be sufficient to handle
current up to the bypass current limit level.
4. The resistance of the trace from the load return to
PGND (Pin 11) should be kept to a minimum. This
minimizes any error in DC regulation due to differ-
ences in the potential of the internal signal ground
and the power ground.
5. For good thermal coupling, PCB vias are required
from the pad for the TDFN exposed paddle to the
ground plane. The via diameter should be 0.3mm to
0.33mm and positioned on a 1.2mm grid.
Figure 4: AAT1171 Evaluation Board
Top Side Layout.
Figure 5: AAT1171 Evaluation Board
Bottom Side Layout.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [e-mail] • www.skyworksinc.com
201999B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 20, 2013
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