Mitsubishi Motors Using Analog Devices’ Low-Power Isolation Technology For i-MiEV

Mitsubishi Motors Corporation has adopted Analog Devices, Inc.’s iCoupler digital isolators to develop a safe, reliable and efficient Li-ion battery power system for the i-MiEV electric vehicle.

The i-MiEV has a single-charge range of 160 kilometers (10-15 mode cycle) and features a three-way charging system that allows a driver to charge the battery at home at 100V or 200V or at a remote quick-charge station. The i-MiEV will be introduced in Japan during calendar year 2010.

Advances in battery technology for hybrid/electric vehicles require similar advances in isolation technology, such as higher levels of integration, temperature resistance and interfaces that eliminate the need for external signal conditioning. ADI’s digital isolation technology is effective for meeting these stringent requirements.

—Thomas Wessel, vice president, Automotive Group, Analog Devices

ADI’s ADuM1402W and ADuM1201W iCoupler digital isolators provide the means to transmit data across the safety isolation barriers between the high-voltage Li-ion battery system electronics and standard vehicle electronic systems. The iCoupler isolators addressed additional requirements such as small size, low power consumption, and extended battery life for longer cruising ranges and maximum service life for the vehicle.

iCoupler products consume one-tenth to one-sixth of the power of optocouplers at comparable signal data rates (e.g. 0.8 mA per channel maximum @ 0 Mbps to 2 Mbps during 3 V operation). iCoupler digital isolators are available in industry-standard, small RoHS-compliant, SOIC (small-outline integrated circuit) packages.

With more than 300 million channels deployed throughout the industry, ADI’s proven iCoupler technology is based on chip-scale transformers, rather than the LEDs and photodiodes used in optocouplers, which ensures higher data rates, lower power consumption, and more stability over the life time of the system, according to the company.

By fabricating the transformers using wafer-level processing, iCoupler channels can be integrated with each other and other semiconductor functions at low cost. iCoupler transformers are planar structures formed from CMOS and gold metal layers. A high breakdown polyimide layer underneath the gold layer insulates the top transformer coil from the bottom. CMOS circuits connected to the top coil and bottom coil provide the interface between each transformer and its external signals. Automotive grade versions are qualified for 125 °C operation per AEC-Q100.