AAT1138 Datasheet, PDF (1/21 Pages) Skyworks Solutions Inc. – 2A Step-Down Converter with Adjustable Input Current Limit

DATA SHEET
AAT1138
2A Step-Down Converter with Adjustable Input Current Limit
General Description
The AAT1138 is a 2A synchronous step-down converter
with an integrated current-limiting load switch designed
for precise input current control applications. By guard-
ing against excessive input current, the AAT1138 enables
the system designer to maximize the output current
from the step-down converter while protecting the input
supply. It is designed for protection of 5V USB ports and
3.3V supplies from heavy load transient conditions com-
monly seen with high data rate modem applications.
The AAT1138 integrates a programmable current limited
P-channel MOSFET load switch to protect the input sup-
ply against large currents which may cause the supply to
fall out of regulation. Current limit threshold is pro-
grammed by an external resistor from SET to ground. It
can be adopted to control loads of the input supply that
requires up to 1.4A.
The AAT1138’s internal step-down converter is a 2A,
1.2MHz constant frequency current mode PWM step-
down converter. The step-down converter can run at
100% duty cycle for low dropout operation. The output
voltage can be regulated as low as 0.6V.
The AAT1138 is available in a Pb-free, low profile, 16-pin
3mm x 4mm TDFN package. The product is rated over
the -40°C to 85°C temperature range.
Features
• V_IN Range: 2.5V to 5.5 V
• V_{OUT Range: 0.6V to VPVIN}
• System Current Limited Load Switch
▪ Programmable Over-Current Threshold
▪ < 1μs Fast Transient Response to Short Current
▪ 145mΩ Typical RDS(ON)
• Step-Down Converter
▪ Up to 2A Output Current
▪ 95% Peak Efficiency
▪ 1.2MHz Switching Frequency
▪ ^{135mΩ Low R}DS(ON) ^{Internal Switches}
▪ 100% Duty Cycle Low Dropout Operation
▪ ^{Soft Start}
• Under-Voltage Lockout
• Independent Enable Pins
• <2μA Shutdown Current
• Over-Temperature and Current Limit Protection
• Low Profile 16-pin 3mm x 4mm TDFN Package
• -40°C to 85°C Temperature Range
Applications
• Cellular Phones
• MP3 Players
• PDAs and Handheld Computers
• Portable Media Players
• USB Devices
Typical Application
V_IN: 2.5V - 5.5V
SYSIN
SYSOUT
C_IN
AAT1138 _PVIN
1μF
TDFN34-16
ENSYS
SVIN
ENBUCK
SW
R_SET
11.3kΩ
SET
PGND
FB
GND
C_SYSOUT
Ceramic Cap 22μF
+ Large Tantalum Cap
L 2.2μH
R2
267kΩ
R1
59.0kΩ
C_OUTB
22μF
V_OUT: 3.3V/
Up to 2A load pulse
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [e-mail] • www.skyworksinc.com
201978B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 15, 2013
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