Freescale Semiconductor has announced a highly integrated 14-cell lithium-ion battery cell controller for industrial and automotive applications, designed to cost effectively meet the stringent requirements for ASIL-C functional safety.
With fourteen cell balancing transistors, a current sensor with ±0.5% accuracy from milliamps to kiloamps, and 2 Mbps communication transceiver interface integrated into a single 64-pin QFP package, Freescale’s MC33771 battery cell controller and companion MC33664 isolated communications interface deliver robust, reliable performance for 48 V battery systems, enabling economical scalability beyond 1000 volts. The solution’s built-in diagnostics help protect automotive and industrial battery packs against critical fault conditions, and its transformer coupled isolated high speed transceiver eliminates the need for expensive isolated CAN busses to meet ASIL-C requirements. Together, these features make the solution ideal for a broad range of automotive and industrial applications including 48 V battery packs, hybrid and electric cars, E-bikes and energy storage systems.
The MC33771 incorporates many critical functions required for controlling a single 48 V battery pack, including the capability to synchronously measure currents and voltages with 2 millivolts of accuracy within 65 us, making it easier to meet ISO 26262 ASIL-C requirements. Embedded functional verification and fault diagnostics enable compliance with ISO 26262 ASIL-C functional safety standards without additional external circuitry. For higher voltage systems, the integrated daisy chain differential transceiver communicates at 2 Mbps using robust transformer coupled isolation up to 3750 volts instead of expensive isolated CAN busses, while the MC33664 connects the battery pack directly to the system MCU’s dual SPI interface using the same transformer coupled isolation. Freescale’s battery cell controller solution delivers exceptional performance with a lower system bill of materials and robust system isolation for ASIL-C rated battery packs.
Additional features include:
- 9.6 V = VPWR = 61.6 V Operation, 70 V transient
- SPI or isolated 2 MHz differential communication
- Current sensor with ±0.5% accuracy from milliamps to kiloamps
- 14x differential cell voltage measurement and stack voltage measurement
- Synchronized cell voltage/current measurement
- Coulomb counting
- 7x ADC/GPIO/temperature sensor inputs
- Addressable on initialization
- Onboard 300 mA passive cell balancing
- Low-power modes
- 64-pin QFP package
The MC33771 and MC33664 devices are sampling now. The versions for the industrial market are expected to be in production by Q1 2015 and the versions for the automotive market are planned for production by Q3 2015. More information