Convertor ICs shrink step-down supplies

Constant-frequency current-mode step-down converters in 3 x 3mm TDFN packages require no external compensation components and offer designers highly compact and easy-to-implement solutions.

New from Advanced Analogic Technology, the AAT1112 and AAT1145 are 1.5 and 1.2A constant-frequency current-mode step-down converters in 3 x 3mm TDFN packages that require no external compensation components and offer designers highly compact and easy-to-implement solutions.

Many portable electronics devices contain circuitry that must be powered from a 3.3V rail.

Unlike comparable voltage-mode step-down converters, the current-mode AAT1112 and AAT1145 enable a lithium-ion battery input to a 3.3V output at full rated current.

These devices also minimise the size of the entire solution without forcing the system designer to iteratively determine the correct external compensation components.

The AAT1112 supplies up to 1.5A output current from a 2.4 to 5.5V input.

The AAT1145 supplies up to 1.2A output current from a 2.5 to 5.5V input.

Output voltage can be regulated from 0.6V up to the input voltage level.

The devices also help extend battery life by running at 100 percent duty cycle for low dropout operation and by offering up to 95 percent power efficiency.

Slope-compensated current mode PWM control enables the use of inductor values as low 1uH; and the high 1.5 and 1.4MHz switching frequency enables the use of small external components, resulting in a small total solution.

The AAT1112 and AAT1145 offer integrated soft start and short-circuit and thermal fault protection.

They also feature a low maximum shutdown current of 1uA.

Rated over the -40 to +85C temperature range, the AAT1112 step-down converter comes in both a Pb-free, 3 x 3mm, 12-lead TDFN package or Pb-free, 2.75 x 3mm, 12-lead TSOPJW package.

The AAT1145 step-down converter comes in a Pb-free, 3 x 3mm, 10-lead TDFN package.

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