AAT1121IES-0.6-T1 Advanced Analog Technology, Inc., AAT1121IES-0.6-T1 Datasheet - Page 14

• Manufacturer Part Number: AAT1121IES-0.6-T1
• Description: 1.5MHz, 250mA Step-Down Converter
• Manufacturer: Advanced Analog Technology, Inc.

Layout
The suggested PCB layout for the AAT1121 is
shown in Figures 2, 3, and 4. The following guide-
lines should be used to help ensure a proper layout.
1. The input capacitor (C1) should connect as
2. C2 and L1 should be connected as closely as
3. The feedback pin (Pin 4) should be separate
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closely as possible to VP (Pin 1), PGND (Pin 8),
and GND (Pin 3)
possible. The connection of L1 to the LX pin
should be as short as possible. Do not make the
node small by using narrow trace. The trace
should be kept wide, direct and short.
from any power trace and connect as closely as
possible to the load point. Sensing along a
Figure 2: AAT1121 Evaluation Board
Top Side Layout.
Figure 4: AAT1121 Evaluation Board
Bottom Side Layout.
1.5MHz, 250mA Step-Down Converter
4. The resistance of the trace from the load return
5. A high density, small footprint layout can be
high-current load trace will degrade DC load
regulation. Feedback resistors should be
placed as closely as possible to the FB pin (Pin
4) to minimize the length of the high imped-
ance feedback trace. If possible, they should
also be placed away from the LX (switching
node) and inductor to improve noise immunity.
to PGND (Pin 8) and GND (Pin 3) 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.
achieved using an inexpensive, miniature, non-
shielded, high DCR inductor.
Figure 3: Exploded View of AAT1121
Evaluation Board Top Side Layout.
AAT1121
1121.2007.03.1.2