AAT1121 Datasheet, PDF (9/19 Pages) Advanced Analogic Technologies – 1.5MHz, 250mA Step-Down Converter

Functional Block Diagram
FB
VIN
DATA SHEET
AAT1121
1.5MHz, 250mA Step-Down Converter
VP
Err
Amp
Voltage
Reference
EN
INPUT
DH
Logic
LX
DL
GND
PGND
Functional Description
The AAT1121 is a high performance 250mA, 1.5MHz
monolithic step-down converter designed to operate with
an input voltage range of 2.7V to 5.5V. The converter
operates at 1.5MHz, which minimizes the size of external
components. Typical values are 3.3μH for the output
inductor and 4.7μF for the ceramic output capacitor.
The device is designed to operate with an output voltage
as low as 0.6V. Power devices are sized for 250mA cur-
rent capability while maintaining over 90% efficiency at
full load. Light load efficiency is maintained at greater
than 80% down to 1mA of load current.
At dropout, the converter duty cycle increases to 100%
and the output voltage tracks the input voltage minus
the R_DS(ON) drop of the P-channel highside MOSFET.
A high-DC gain error amplifier with internal compensa-
tion controls the output. It provides excellent transient
response and load/line regulation. Soft start eliminates
any output voltage overshoot when the enable or the
input voltage is applied.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [e-mail] • www.skyworksinc.com
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201974B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 15, 2013