18V boost regulator for mobile product displays

April 05, 2013 // By Graham Prophet
ams' AS1345 is a miniature step-up DC-DC regulator that maintains high efficiency in power supplies designed for small, medium-sized or large displays in mobile products. System developers can re-use their power circuit design across multiple product variants with different display sizes.

By providing four variants with different peak coil current limits of 100mA, 200mA, 350mA and 500mA, ams has optimised the efficiency of the AS1345 across a wide range of loads. The AS1345’s output voltage can also be selected, with fixed-output versions available at 12V, 15V and 17V, and adjustable versions enabling the designer to configure an output between 5V and 18V. All variants share the same footprint and pin-out. System designers can therefore maintain a common power supply design across a range of displays by selecting the AS1345 variant with the most appropriate output voltage and peak coil current, and changing inductor and capacitor values appropriately. The AS1345 supports OLED displays ranging in size from 130mm 2 to 3700mm 2.

With a footprint of 2mm x 2mm, the AS1345 is suited to display power circuits of end products, such as mobile phones and e-readers, that require long battery run-time and that impose severe board space constraints. Its high-frequency hysteretic control loop operates with very small external components. It also includes integrated MOSFETs for power and isolation switching.

The step-up converter operates from an input voltage range of 2.9V to 5.0V, and so is suitable for use with a single lithium-ion battery, as well as with other battery types and configurations. It is capable of supplying a 20mA output current at 18V from a single li-ion battery. Supporting long battery run-time between charges, the device features a low quiescent current of 25µA (typical). It may be disconnected from the battery in shut-down mode. The AS1345 18V step-up regulator is priced at $0.49 (1,000). An evaluation kit for the DC-DC Step-up Converter AS1345 is available online from ams.

For further information on the AS1345; www.ams.com/DC-DC-Converter/AS1345