Automotive lithium battery control set to grow in complexity

Monitoring automotive batteries will become increasingly important, but also increasingly complex, according to Erik Soule, general manager of Linear Technology's signal conditioning business unit. "A lot of bad things can happen if you don't manage these batteries properly." Linear has begun to address the issues with the LTC6802, launched a couple of years ago. "But the electronics have proved to be tougher than people thought for a number of reasons," he told New Electronics. "For instance, there are high voltages and the process needs extreme precision, as well as noise immunity. It's a problem when inverters switch at 20kHz because they radiate emi with a large number of harmonics, so you also have to filter all that out." Other requirements of these battery controllers include reliability, fault tolerance and diagnostics. "All these requirements are being driven by the ISO26262 automotive safety standard," he noted. Along with answering such questions as 'is the cell charged?', 'how much energy is left?' and 'are the cells balanced?', battery controllers will have to work with 1mV precision. "And the electronics in hybrid vehicles will be on 24/7 for 15 years maybe," Soule added. Linear is now working on new generations of its battery controllers. "We will probably need to build these on a process with 100V analogue capability, but with fine cmos," he said. "The devices will have better noise immunity and will be better at being able to meet safety requirements through the provision of built in self test features."