Automotive Signal Processing
Volume 8, Issue 10 YOUR SEMICONDUCTOR SOLUTIONS RESOURCE

ADI in Hybrid Electric Vehicles (HEVs)

In today's environmentally conscious world, preserving and reusing resources is imperative. Appropriately enough, Analog Devices has applied this principle in developing products for hybrid electric vehicles (HEVs). Leveraging years of experience in developing and supplying ICs for precision instrumentation systems, ADI has developed a product portfolio ideal for HEV systems. Measurement problems posed by high voltage HEV battery stacks have introduced new challenges. ADI responded by developing innovative solutions to meet these new needs. Patents are pending on some of these new technology developments.

Solution
One of the two main focus areas for ADI in HEV systems today is the transmission, where precise synchronization must be maintained between the internal combustion engine (ICE) and electric drive motor. Robust wire-wound resolvers monitor rotational position and provide input to high resolution resolver-to-digital converters (RDCs), which must perform accurately in the presence of many error sources and under demanding physical conditions. The accumulation of many years of experience spent designing and testing RDCs for the harsh environments of assembly line welding robots or flap control in aerospace industries, for instance, has enabled ADI to introduce the AD2S1205, a new RDC with features optimized for the HEV market.

A second area of focus in HEVs is in the monitoring of multiple Li-Ion batteries, which are replacing Ni-MH in the battery stacks of automobiles scheduled for mass production beginning in 2009. Both OEMs and Tier 1 suppliers are committed to making such battery stacks as safe as possible. Measurement systems need to be highly reliable and accurate over the lifetime of the car while simultaneously being as low cost as possible. Adding to the challenge is the fact that such systems operate in a 300 V environment. ADI is responding to these challenges by employing innovative solutions in a new range of integrated monitoring products featured in the next several pages.

Industry's First Digital Isolators Qualified for Automotive Systems

High voltage battery stacks used in hybrid vehicles have introduced the need for galvanic isolation to protect low voltage electronic systems. The isolation technology employed in this application must not degrade over the lifetime of the vehicle nor because of the harsh operating conditions sometimes encountered through the changing seasons. In addition, this technology needs to be low cost while guaranteeing full specifications over the automotive temperature range.

Solution
Analog Devices' iCoupler® digital isolators utilize standard CMOS processors and are insensitive to temperature variation. This recently released family of devices, shown in the iCoupler products table on Page 6, are AEC-Q100 qualified to 125°C and use the same material set as their well established counterparts. All are part of the ADI family of iCoupler products with more than 150 million channels of isolation shipped to date. These 2-channel, 3-channel, and 4-channel digital isolators have data rates up to 25 Mbps and propagation delays as low as 32 ns. Power consumption is extremely low, which is ideal in energy efficient vehicles. All products are available in small, low profile, surface-mount, 8-lead SOIC_W or 16-lead SOIC_W packages, and come with safety certifications from UL, CSA, and VDE. All feature isolation ratings up to 2.5 kV rms and working voltages up to 400 V rms.

iCoupler

Automotive iCoupler Features

  • AEC-Q100 qualified digital isolation up to 125°C
  • Data rates up to 25 Mbps
  • Propagation delays as low as 32 ns
  • 2-channel, 3-channel, and 4-channel versions available in 8-lead SOIC_W or 16-lead SOIC_W packaging

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