Boost Converter with USB Power Switch
General Description
The AAT1275 SwitchReg is a 2MHz, 500mA syn-
chronous boost converter with an integrated current-
limiting load switch controlled output. The AAT1275
operates from a single-cell Lithium-ion/ polymer bat-
tery source and provides a regulated 5V, current
limit controlled output to support USB port V
BUS
applications in portable consumer electronic prod-
ucts. The AAT1275 can support both USB 2.0 host
port and USB on-the-go operation, as well as gen-
eral purpose applications where a 5V supply with a
user programmable current limit is needed.
The high efficiency boost converter section of the
AAT1275 is typically set for a 5V output and can
deliver up to 500mA load current to support USB
V
BUS
operation from an input supply as low as
2.7V. The high boost converter switching frequen-
cy (up to 2.0MHz) provides fast load transient and
allows the use of small external components. Fully
integrated control circuitry simplifies system design
and reduces total solution size.
The integrated, programmable current limiting load
switch provides USB port protection for portable
devices allowing the AAT1275 to supply a 5V USB
V
BUS
up to 500mA. The load switch provides an
active low fault flag to alert the system in the event
of an over-current condition applied to the
AAT1275 output.
The AAT1275 is available in the Pb-free, space-
saving 12-pin TSOPJW and 16-pin TDFN34 pack-
ages and is rated over the -40°C to +85°C operat-
ing temperature range.
AAT1275
Features
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SwitchReg
™
High Frequency Boost With 5V / 500mA
Output Capability From a Single-Cell Lithium-
Ion/Polymer Battery
Input Voltage Range: 2.7V to 5V
V
OUT1
Adjustable or Fixed (5V)
>90% Efficiency
Up to 2MHz Switching Frequency
True Load Disconnect
Load Switch With Programmable Current Limit
Over-Temperature, Over-Current Protection
Inrush Current Limit
Fault Report
Low Shutdown Current < 1µA Typical
-40°C to +85°C Temperature Range
TSOPJW-12 and TDFN34-16 Packages
Applications
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USB On-the-Go
Cell Phones
Digital Still Cameras
PDAs and Portable Media Players
Smart Phones
Other Hand-Held Devices
Typical Application
L1 2.2µH
LIN
SW
OUT1
V
IN
C
IN
4.7µF
10k
Fault
Enable
IN
VCC
R
FB1
432k
FB
C
OUT1
4.7µF
AAT1275
FLT
EN
OUT2
SET
R
FB2
59k
V
BUS
Output
C
OUT2
1µF
R
SET
GND
1275.2007.01.1.3
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ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
