New Industry Products

Coilcraft Releases Tiny Step-Up Transformers for Energy Harvesting Applications

March 23, 2010 by Jeff Shepard

Coilcraft has unveiled a line of ultra-miniature step-up transformers that are well suited for use with energy harvesting ICs. The LPR6235 family offers turns ratios as high as 1:100 and a coupling coefficient (k) of 0.95 or more in a surface mount package measuring just 6 mm square by 3.5mm high.

Energy harvesting is the process of capturing low levels of thermal, kinetic, RF, or solar energy and stepping it up to a dc-dc converter that accumulates and manages power for low energy electronic devices. These are typically autonomous sensors and transmitters located where there is no other practical source of power.

The LPR6235 was chosen by Linear Technology for use with its new LTC3108 Ultralow Voltage Step-Up Converter and Power Manager. Because of their extremely high efficiency, low DCR and 1:100 turns ratio, Coilcraft’s transformers allow the IC to operate from input voltages as low as 20mV.

In addition, energy harvesting applications often have size constraints, which makes the LPR6235’s 6 x 6 x 3.5mm body and 480 gram weight beneficial.

Four models are available with primary-to-secondary turns ratios of 1:100, 1:90, 1:50 and 1:20. Lower ratios are designed for use with energy sources such as thermopiles that output higher voltages. Coilcraft can produce versions with custom turns ratios and also offers the LPR4012 family of transformers with ratios from 1:10 to 1:1.5 in an even smaller package.

The efficiency of the LPR6235 transformers comes from their exceptional >0.95 coupling factor and primary winding dc resistance of 0.08 to 0.2Ω. They feature 100V winding-to-winding isolation and primary winding inductance values from 7.5 to 25µH. Current ratings range from 1.6 to 0.7A.

The parts are RoHS compliant and are built for operating temperatures from -40 to +85°C and storage temperatures from -40 to +125°C.

Pricing for the LPR6235 transformers is $0.61 U. S. each in quantities of 1,500. They are stocked for immediate delivery in 7-inch reels of 350 pieces.