Cary, Ill. Coilcraft has unveiled a line of ultra-miniature step-up transformers, which can be used 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 that measures 6-mm square x 3.5-mm high.
Energy harvesting captures low levels of thermal, kinetic, RF, or solar energy and steps 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, said Coilcraft.
The LPR6235 was chosen by Linear Technology for use with its new LTC3108 ultra-low voltage step-up converter and power manager. Due to 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 20 mV.
In addition, energy harvesting applications often have size constraints, which make the LPR6235 device’s small package and low weight of 480 gram well-suited for the applications.
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 also offers custom turns ratios. The LPR4012 family of transformers provides ratios from 1:10 to 1:1.5 in a smaller package.
The efficiency of the LPR6235 transformers comes from their >0.95 coupling factor and primary winding DC resistance of 0.08 to 0.2 ohms. The devices feature 100-V winding-to-winding isolation and primary winding inductance values from 7.5 to 25 uH. Current ratings range from 1.6 to 0.7 amps.
The RoHS-compliant parts operate over the temperature range of -40°C to +85°C. Storage temperature ranges from -40°C to +125°C.
Availability: Immediate delivery in 7-inch reels of 350 pieces.
Pricing: $0.61 each in quantities of 1,500.
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