AAT2113B Datasheet, PDF (15/22 Pages) Skyworks Solutions Inc. – 3.3MHz, Fast Transient 1.5A Step-Down Converter in an 2mm x 2mm Package

DATA SHEET
AAT2113B
3.3MHz, Fast Transient 1.5A Step-Down Converter in an 2mm x 2mm Package
Since R_DS(ON), quiescent current, and switching losses all
vary with input voltage, the total losses should be inves-
tigated over the complete input voltage range.
Given the total losses, the maximum junction tempera-
ture can be derived from the θ_JA for the FTDFN22-8
package, which is 70°C/W.
T_J(MAX) = P_TOTAL · Θ_JA + T_AMB
PCB Layout Considerations
The suggested PCB layout for the AAT2113B is shown in
Figures 3 and 4 (fixed version) or Figures 6 and 7 (adjust-
able version). The following guidelines should be used to
help ensure a proper layout:
1. The input capacitor (C1) should be connected as
close as possible to VP and PGND.
2. The output capacitor and L1 should be connected as
closely as possible. The connection of L1 to the LX
pin should be as short as possible.
3. For the fixed output version, the feedback trace or
FB pin should be separated 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. For the adjustable ver-
sion, the trace connecting the FB pin to resistors R1
and R2 should be as short as possible by placing R1
and R2 immediately next to the AAT2113B. The
sense trace connection from R1 to the output volt-
age should be separate from any power trace and
connect as closely as possible to the load point. The
external feed-forward capacitor C2 should be con-
nected as close as possible in parallel with R1 for
enhanced transient response.
4. The resistance of the trace from the load return to
PGND 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.
5. Connect unused signal pins to ground to avoid
unwanted noise coupling.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [e-mail] • www.skyworksinc.com
202003A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 24, 2012
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