ASIL-C Functional Safety Simplified with 48-V Battery-Cell Controller

ASIL-C Functional Safety Simplified with 48-V Battery-Cell Controller

Freescale’s 14-cell lithium-ion (Li-ion) battery-cell controller meets the stringent requirements for ASIL-C functional safety in industrial and automotive applications—at a lower cost. The MC33771 controller and companion MC33664 isolated communications interface deliver reliable performance for 48-V battery systems, enabling economical scalability beyond 1000 V.

The device features 14 cell-balancing transistors, a current sensor with ±0.5% accuracy from milliamperes to kiloamperes, and 2-Mbit/s communication transceiver interface integrated into a single 64-pin QFP package. 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 buses to meet ASIL-C requirements.

Currents and voltages can be synchronously measured with 2 mV of accuracy within 65 µs, making it easier to meet ISO 26262 ASIL-C requirements. Embedded functional verification and fault diagnostics enable compliance without additional external circuitry.

For higher-voltage systems, the integrated daisy-chain differential transceiver communicates at 2 Mbits/s using robust transformer-coupled isolation up to 3750 V instead of expensive isolated CAN buses, while the MC33664 connects the battery pack directly to the system MCU’s dual SPI interface using the same transformer-coupled isolation.


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