Battery management IC maximises cell life and range for hybrid and electric vehicles

Renesas Electronics has released its fourth-generation Li-ion battery management IC that provides unmatched lifetime accuracy. The ISL78714 offers accurate cell voltage and temperature monitoring, as well as cell balancing and extensive system diagnostics to guard 14-cell Li-ion battery packs while maximising driving time and range for hybrid and electric vehicles.

“The ISL78714 battery management IC enables battery management systems with a best-in-class combination of battery pack monitoring accuracy, fast data acquisition, and fault checking features,” said Niall Lyne, senior director of Product Marketing and Applications, Automotive Mixed-Signal/Power and Video, Renesas Electronics Corporation. “Our Formula E technology partnership with Mahindra Racing is already helping them win on the race track. Together, we designed and integrated a low-voltage Li-ion battery management system featuring ISL78714 ICs and RH850 microcontrollers in Mahindra Racing electric race cars.”

The feature-rich device monitors and balances up to 14 series-connected cells with ±2mV accuracy over automotive temperature ranges, allowing system designers to make informed decisions based on absolute voltage levels. The device comprises a precision 14-bit ADC and associated data acquisition circuitry. The device also provides up to six external temperature inputs (two available from GPIOs) and incorporates fault detection and diagnostics for all key internal functions.

The device satisfies the stringent reliability and performance demands of battery pack systems for all EV variants as well as HEV/PHEV, with safety features allowing automotive manufacturers to fulfil the ISO 26262 automotive safety integrity level (ASIL D). The device also monitors and reads back temperature, open-wire conditions, over/under voltage, and fault status for 112 cells in less than 10ms, or 70 cells in 6.5ms.

Multiple IC’s can be connected via a proprietary daisy chain that maintains systems up to 420 cells (30 ICs) that offers industry-leading transient and EMC/EMI immunity, exceeding automotive demands. The device’s daisy-chain architecture employs low-cost capacitive or transformer isolation, or a blend of both, with twisted-pair wiring to stack multiple battery packs together while guarding against hot plug and high voltage transients. A watchdog timer automatically shuts down a daisy-chained IC if communications are lost with the master MCU.