NXP Semiconductor has introduced the BMI7018, a new lithium-ion battery-cell controller integrated circuit (IC) designed for industrial applications. The BMI7018 targets key sectors such as energy storage systems (ESS) and uninterruptible power supply (UPS) systems, offering advanced battery management capabilities.

The BMI7018 offers a transport protocol link (TPL3 - proprietary isolated daisy chain protocol of NXP) and Serial Peripheral Interface (SPI) for communication with the host microcontroller unit (MCU).

These devices support high-precision cell voltage and temperature measurements along with various cell voltage balancing strategies. Aside from an SPI interface to enable direct communication with the host MCU, they provide alternatively a daisy chain communication interface that supports capacitive and inductive isolation between nodes.

Features and benefits of BMI7018

• Ambient temperature range: from –20°C to +60°C
• Support for cell voltage and cell-temperature measurements from the host MCU to the cell
• Cell voltage measurement
  • 4 to 18 cells per device
  • Operating voltage range from 9 V to 90 V
  • Supports bus bars voltage measurement with -3 V to +5 V input voltage
  • 16-bit resolution and up to ±0.8 mV typical measurement accuracy with ultra-low long-term drift
  • Integrated configurable digital filter
• External temperature and auxiliary voltage measurements
  • One analog input for absolute measurement, 5 V input range
  • Eight analog inputs configurable as absolute or ratiometric, 5 V input range
  • 16-bit resolution and ±5 mV typical measurement accuracy
  • Integrated configurable digital filter
• Internal measurement
  • Two redundant internal temperature sensors
  • Supply voltages
  • External transistor current
• Cell voltage balancing
  • 18 internal balancing field effect transistors (FET), up to 360 mA peak with 0.5 Ω R_DSon per channel (typ.)
  • Support for simultaneous passive balancing of all channels with automatic odd/even sequence
  • Global balancing timeout timer
  • Timer controlled balancing with individual timers with 10 s resolution and up to 45 h duration
  • Voltage-controlled balancing with global and individual undervoltage thresholds
  • Temperature-controlled balancing; if balancing resistors or the IC are in overtemperature, balancing is interrupted
  • Configurable pulse width modulation (PWM) duty cycle balancing
  • Automatic pause of balancing during measurement with configurable filter settling time
  • Configurable delay of the start of balancing after transition to sleep
  • Automatic discharge of the battery pack (emergency discharge)
  • Constant current cell balancing to compensate for the balancing current variation due to cell voltage variation
• I²C-bus leader interface to control external devices, for example, EEPROMs and security ICs
• Configurable alarm output
• Cyclic wake-up to monitor the pack and the balancing function during sleep.
• Capability to wake up the host MCU via a daisy chain in case of a fault event.
• Host interface supporting SPI or isolated daisy chain communication (TPL3)
  • 2 Mbit/s data rate for TPL interface
  • 4 Mbit/s data rate for SPI interface
• TPL3 daisy chain communication supports
  • Two-wire daisy chain with capacitive or inductive isolation
  • Protocol supporting up to six daisy chains and 62 nodes per chain
• Unique device ID with dynamic addressing
• Operation modes
  • Active mode FP (12 mA typ.)
  • Sleep mode LP (60 µA typ.)
  • Deep Sleep mode ULP (15 µA typ.)

Click here to learn more about BMI7018.