Battery cell controllers for low-cell-count connected designs

September 17, 2015 // By Graham Prophet
Performance and functional safety features are optimised for 14V Li-ion battery packs that are replacing traditional automotive lead-acid batteries.

Freescale Semiconductor’s MC33772 3- to 6-cell lithium-ion battery cell controller is designed to reduce BOM cost, increase operating robustness and meet stringent functional safety requirements for automotive and industrial battery systems.

Together with its previously announced MC33771 14-cell battery cell controller, the MC33772 product expands Freescale’s hardware- and software-compatible single-chip battery cell controller portfolio to cover 3- to 14-cell solutions. Supporting a broad array of battery chemistries, including lithium iron phosphate, lithium nickel manganese cobalt oxide, lithium titanate, and lithium polymer, Freescale’s cell controller portfolio helps designers scale configurations to meet different battery management needs without requiring new R&D investments. The cell controllers have advanced diagnostics and functional verification supporting ISO 26262 ASIL-C requirements within a single chip.

Lead-acid automotive batteries, Freescale notes, are increasingly being replaced by Li-ion chemistries to reduce weight, increase reliability and boost energy efficiency for engine start-stop systems and energy recuperation technologies. Recent advances in Li-ion battery chemistry for cold temperature operation and cold cranking power now enable Li-ion batteries to displace lead-acid even as the starter battery. As a result, the inherent challenges of overcharge, overheating and internal short circuit are increasingly managed by electronics. To maintain safe operating conditions and ensure system-wide control of the battery, next-generation battery cell controllers like Freescale’s must provide accurate, reliable battery diagnostics and high speed communication of status.

The MC33772 battery cell controller supports this change, providing a single chip solution optimised for all critical performance and safety duties, and featuring robust functional verification supporting ISO 26262 ASIL-C requirements, which help protect automotive and industrial battery packs against critical fault conditions. Higher level ASIL-D system implementations can also be realised using multiple Freescale battery cell controllers for redundancy.

In addition to 14V Li-ion battery packs, the MC33772 product’s optimised feature set is suited for reducing system electronics BOM cost in a broad range of automotive and industrial battery management applications, including 48V battery systems, high voltage hybrid and electric cars, E-bikes and energy storage systems. The MC33772 delivers an optimal balance of measurement accuracy, scalability and high speed isolated communications. It supports rapid, 2 Mbps communication of battery health and conditions for a variety of battery management system topologies, including centralised, distributed CAN and distributed daisy chain systems.

Support for the MC33771 and MC33772 battery cell controllers and the MC33664 transformer physical layer comprises the KIT33771ASP1EVB, KIT33772ASP1EVB and KIT33664EVB evaluation kits.

The MC33771, MC33772 and MC33664 products are sampling now. The MC33771 and MC33664 products are expected to be in production by Q4 2015, while the MC33772 product is planned for production by Q2 2016. The MC33771 will be priced at $4.86 and the MC33772, from $3.46 (10,000) depending on cell count and feature set. The MC33664 will be $1.65 (10,000)


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