The MC33771x Battery Cell Controllers targets hybrid electric and electric-vehicle battery systems.
By William Wong, Senior Technology Editor, Electronic Design
NXP’s MC3377x Battery Cell Controllers (see figure) can handle seven or 14 cells. It’s also possible to link multiple chips together to address larger arrays. The chips are able to convert cell measurements for a 96-cell, high-voltage battery in under 546 µs. It can then deliver this information to the pack controller within 4.1 ms with a typical accuracy of ±0.8 mV. System SPI communication can operate at 4 Mbits/s or 2 Mbits/s when using transformer isolation.
This system enables highly accurate cell impedance calculations for state-of-health monitoring using unique synchronized current sensing. They can detect internal and external faults, such as open lines, shorts, and leakages. The chips have an integrated sleep mode while supporting over/undervoltage and temperature monitoring.
The MC3377x incorporates 0.8-Ω MOSFETs with dedicated timers for each cell for effective and simultaneous charge-balancing of each cell. They also provide embedded functional safety mechanisms and diagnostics to effectively support the highest functional safety goals.
The family, which includes the MC33771B and MC33772B, is designed to meet ISO 26262 requirements, up to ASIL D. They also have qualified in compliance with AECQ-100.