In October 2020, after the rounds of selection from the editors of 21IC, Renesas’ 14-cells battery management IC ISL78714 stood out from the rest and won the 2020 Top 10 Power Products Technical Breakthrough Awards. The ISL78714 was launched in August 2019 and offers unmatched lifetime accuracy performance.
In HEV (hybrid electric vehicle), EV (electric vehicle), and ESS (energy storage system) applications, it is necessary to meet the stringent ASIL-D functional safety requirements economically and efficiently. New applications for critical mission increasingly require support from automotive and industrial batteries, so overcharge, overheating, internal short circuit or overload must be controlled to help ensure a safe operating environment. Battery analog front-end controller can accurately measure the differential cell voltage, temperature, to provide accurate and reliable battery diagnosis, which is very important. It is also important to transmit the information quickly and accurately from the analog front-end controller to the battery controller which controls and protects the whole battery pack system thus making full use of the entire battery energy.
Solution system block diagram：
The ISL78714 provides accurate battery voltage and temperature measurement, cell balance and extensive system diagnostics, to protect 14-cells li-ion battery packs and maximize the battery life and mileage of hybrid and electric vehicles (HEV/MHEV/PHEV/BEV).
Within the automotive operating temperature range, the measurement accuracy can reach board level ±2mV within 270us, which helps the system designer to determine the absolute voltage level. The ISL78714 includes a precise 14-bit ADC and related data acquisition circuit.
The ISL78714 meets the safety, reliability, and high-performance requirements of all types of EV battery pack systems, including HEV/PHEV. Embedded functional verification and fault diagnosis can enable auto manufacturers to meet the ISO 26262 Automotive Safety Integrity Level (ASIL D) standard without additional external circuits.
The ISL78714 and ISL78720 isolated communication transceiver from Renesas can optimize the life cycle of various battery structures, including centralized CAN, distributed CAN and distributed daisy chain topology. Dedicated daisy chain connection that supports systems with up to 420 battery cells (30 ICs), providing industry-leading transient and EMC/EMI immunity beyond automotive class requirements. The ISL78714 daisy chain topology uses low-cost capacitive or transformer isolation way, or a combination of both, with twisted pair wiring to stack multiple battery packs together while protecting against hot plug and high voltage transients. When communications with the main MCU are lost, the watchdog timer will automatically shut down the daisy chain IC. It is an alternative to the expensive isolated CAN bus. This scheme can be used as an alternative to CAN based solutions.The battery does not need local microcontroller, voltage regulator and isolated CAN layer, which helps to reduce the cost and simplify the design complexity.
This new battery controller leverages on Renesas' extensive automotive experience and its long history of creating reliable and highly integrated high-performance solutions to reduce the cost of meeting stringent safety requirements.