AAT2138 Datasheet, PDF (1/18 Pages) Skyworks Solutions Inc. – High Current Step-Down Converter with High-Precision Programmable Current Limited Load Switch

DATA SHEET
AAT2138
High Current Step-Down Converter
with High-Precision Programmable Current Limited Load Switch
General Description
Features
The AAT2138 is a high current synchronous step-down
converter with an integrated current-limited load switch
designed for high precision current control applications.
By guarding against excessive input current, AAT2138
enables the system designer to maximize the output cur-
rent from the step-down converter while protecting the
input supply. It is designed for protection of USB ports
from heavy load transient conditions commonly seen
with high data rate modem applications.
AAT2138 integrates a high precision programmable cur-
rent limited P-channel MOSFET load switch to protect the
input supply against large currents which may cause the
supply to fall out of regulation. The current limit thresh-
old is programmed up to 3A by an external resistor
between RSET and ground.
The AAT2138 is a 2.8MHz current mode step-down con-
verter. It utilizes a tiny 1μH inductor and internal com-
pensation to enable it to have an extremely small foot
print. The regulator supports 100% duty cycle operation
for dropout conditions. An external clock in the range of
1MHz to 3MHz can be fed into MODE as a synchronous
signal for the step-down regulator. This feature offers
the flexibility of fine tuning the switching frequency and
optimizing performance in the application.
AAT2138 is available in a Pb-free, low profile, 14-pin
3mm x 3mm TDFN package. The product is rated over
the -40°C to 85°C temperature range.
• Input Voltage Range: 2.7V to 5.5 V
• Output Voltage Range: Down to 3.0V
• Current-Limited Load Switch
- ±10% High Precision
- Programmable Current Limit Range: 500mA to 3A
• High-Current Step-Down Converter
- Efficiency up to 95%
- 85mΩ High-Side; 50mΩ Low-Side FETs
- 2.8MHz Switching Frequency
- 100% Low Dropout Operation
- No External Compensation Required
- PFM/PWM or forced PWM Modes
- 1MHz to 3MHz External Clock Support
• Soft Start
• Independent Enable Pins for Switch and Converter
• Over-Temperature and Over Load Protection
• -40°C to +85°C Temperature Range
• Pb-Free, Low-Profile, 3mmx3mm 14-pin TDFN Package
Applications
• Wireless Modem Data Cards
• Portable Hard Drives
• Portable Memory Card Readers
• Barcode Scanners
• Credit Card Readers
• General USB Powered Devices
Typical Application
V_IN
2.7V-5.5V
Bulk Capacitor
ON
OFF PWM
PFM/PWM
C_IN
1μF
SYSIN
ENSYS
RSET
CIN
0.1μF
REGIN
SW
C_IN
10μF
AAT2138
PGND
ENREG
FB
MODE
AGND
R_SET
1μH
OFF
ON
R1
274k Ω
R2
59k Ω
V_OUT
3.4V/3A
C_OUT
22μF
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [e-mail] • www.skyworksinc.com
202006C • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 18, 2013
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