14 cell battery management chip boosts electric car range 

August 08, 2019 //By Nick Flaherty
Up to 30 Renesas ISL78714 battery management chips in a daisy-chain support a 430 cell battery pack
Up to 30 Renesas ISL78714 battery management chips in a daisy-chain support a 420 cell battery pack

Renesas Electronics has launched its fourth-generation lithium-ion (Li-ion) battery management IC for accurate cell voltage and temperature monitoring, along with cell balancing and extensive system diagnostics to protect 14-cell Li-ion battery packs.

The ISL78714 monitors and balances up to 14 series connected cells with ±2mV accuracy across automotive temperature ranges, letting system designers make informed decisions based on absolute voltage levels. The ISL78714 includes a precision 14-bit analog-to-digital converter and associated data acquisition circuitry. The device also offers up to six external temperature inputs (two available from GPIOs) and includes fault detection and diagnostics for all key internal functions.

The battery managament chip includes safety features enabling automotive manufacturers to achieve the ISO 26262 automotive safety integrity level ASIL D. In addition, the ISL78714 monitors and reads back over/under voltage, temperature, open wire conditions, and fault status for 112 cells in less than 10ms, or 70 cells in 6.5ms.

Multiple devices can be connected together via a proprietary daisy chain that supports systems up to 420 cells using 30 of the management devices with industry-leading transient and EMC/EMI immunity, exceeding automotive requirements. The ISL78714’s daisy-chain architecture uses low-cost capacitive or transformer isolation, or a combination of both, with twisted pair wiring to stack multiple battery packs together while protecting against hot plug and high voltage transients. A watchdog timer automatically shuts down a daisy-chained IC if communications is lost with the master MCU.

“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 fully differential cell input range of ±5V accommodates fuel cell


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