STMicroelectronics and LG Chem have announced plans to develop an automotive battery pack that will extend the potential of electric and hybrid electric vehicles, combining LG Chem’s lithium-ion (Li-ion) battery technology with a battery-management chip from STMicroelectronics.
Today’s hybrids use batteries based on nickel-metal-hydride (NiMH) technology, which use simple control circuits but are heavier and operate at lower voltages. Li-ion batteries offer an energy-to-weight ratio that’s twice that of NiMH batteries and have a very low self-discharge while they aren’t in use.
But Li-ions haven’t seen wide use in higher-power applications since their charge/discharge cycle must be carefully managed to protect them from abuse. The LG Chem Li-ion battery pack manages the charge/discharge cycle by incorporating the STM chip to enable safe and long-term battery reliability at an affordable cost, even in harsh automotive applications like powertrain systems.
The STM chip is manufactured with the company’s proprietary bipolar-CMOS-DMOS (BCD) technology, which combines digital logic circuits, precise analog measurement circuits, and power-handling transistors. Each chip can handle up to 10 Li-ion cells. Also, each chip includes an interface for communicating with other STM battery-management chips in a system, and up to 32 battery-management chips can be connected in cascade to manage batteries delivering up to 1600 V to electric motors.
Often called smart power, BCD enables STM to manufacture three fundamental components on a single low-cost chip: digital logic for high-speed computation, analog circuits for high-precision measurement and control, and power transistors that manage the flow of high electric currents.