IC Does Management for 14 Series-Connected Li-ion Battery Cells

Renesas Electronics has announced its fourth-generation lithium-ion (Li-ion) battery management IC that offers unmatched lifetime accuracy. The ISL78714 provides accurate cell voltage and temperature monitoring, along with cell balancing and extensive system diagnostics to protect 14-cell Li-ion battery packs while maximizing driving time and range for hybrid and electric vehicles (HEV/MHEV/PHEV/BEV).

The feature-rich 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 ISL78714 meets the stringent reliability and performance requirements of battery pack systems for all EV variants including HEV/PHEV, with 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 10 ms, or 70 cells in 6.5 ms.

Multiple ISL78714’s can be connected together via a proprietary daisy chain that supports systems up to 420 cells (30 ICs) that provide 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.

Key Features:

  • Monitors and manages up to 14 cell voltages with ±2mV measurement accuracy
  • Robust two-wire daisy chain communications system using capacitor or transformer coupling up to 1 Mbps
  • Fully differential cell input range of ±5V accommodates fuel cell and bus bar measurement requirements for aging battery packs
  • 15-year board level accuracy (long term drift) of ±6mV at ±6σ
  • High diagnostic coverage for cell voltage and temperature measurements
  • AEC-Q100 Grade-2 qualified and specified for operation from -40°C to +105°C

A battery management system (BMS) reference design is available, which includes five ISL78714 ICs and a RH850/P1M MCU to form a complete 70-cell evaluation platform for external balancing. The reference design kit provides setup and data logging via CAN and UART. Also provided is a GUI, Altium layout files and low-level drivers for the RH850 peripherals and ISL78714. Hardware, software, and interface reference manuals are included, along with an EMC report.

Mass production quantities of the ISL78714 Li-ion battery management IC are available now in a 64-lead TQFP package.

Renesas Electronics | www.renesas.com

 

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