Step-up DC/DC converter for ultraportable systems

23rd May 2006

Advanced Analogic Technologies Inc., Europe

ES Admin

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Ultraportable systems running from single or dual alkaline, NiMH, or NiCd cells need to boost voltage while conforming to strict requirements for battery life and system size. A low-voltage step-up converter from AnalogicTech maintains high efficiency over the entire output current range, requires no external compensation, and provides true load disconnect (TLD) all in a tiny 2.0x2.1mm SC70JW package.

Extending AnalogicTech's family of boost converters, the AAT1265 synchronous fixed frequency step-up converter supplies 100mA to a 3.3V load from a single AA cell and 250mA from dual AA cells. The AAT1265 delivers efficiency up to 93 percent and maintains high efficiency over the entire
load range. A 2MHz switching frequency helps minimise solution footprint by enabling the use of extremely small inductors and capacitors.

Leakage current is a common concern with boost converters. Typically these
devices present a conduction path from the input to the output via the body
diode of the P-channel MOSFET when the system is not active. To eliminate
such power loss, designers often use a load switch and control circuitry to
disconnect the load from the converter. AnalogicTech's AAT1265 solves this
problem with the TLD feature which disconnects the body diode from the
output. This feature extends battery life and simplifies the system design
by eliminating an external load switch and control circuitry.

The AAT1265 also adds a variety of safety features to preserve the integrity
of the device including short-circuit and over-current protection, inrush
current limit, and soft start. Specified over the -40 to +85 degrees C
temperature range, the AAT1265 is available in a Pb-free, compact 2.0x2.1mm
SC70JW-8 package.