L9963E is used in hybrid electric (HE) and all electric (FE) vehicles using lithium battery packs. The integrated circuit embeds all the functions required to perform battery management. A single device can be monitored from 4 to 14 units. Several devices can be stacked vertically to monitor up to 31 battery packs, a total of 434 series batteries. The device can provide the same battery as the one it monitors, and generate stable internal reference through the voltage regulator and guide. Both units need to be surrounded by external components to function.

     It also has two internal bandgaps, which are constantly monitored by internal circuits to ensure measurement accuracy. The microcontroller can also monitor the accuracy of the band gap by reading the conversion of the internally generated reference voltage (VTREF). The main functions of L9963E include monitoring battery and battery pack status through stack voltage measurement, battery voltage measurement, temperature measurement and coulomb counting. Measurement and diagnostic tasks can be performed on demand or periodically with programmable cycle intervals. The measured data can be used by the external microcontroller to perform charge balancing and calculate the state of health (SOH) and state of charge (SOC).

     In typical use, the IC works in normal mode to perform measurement conversion, diagnosis and communication; The device can also be placed in the cyclic wake-up state to reduce the current consumption from the battery: in this state, the main functions are activated periodically. Passive battery balance can be achieved through internal discharge path or external mosfet. The controller can manually control the equalization drive, or start the equalization task for a fixed time. In the second case, when the integrated circuit enters a low power mode called silent balance, the balance can also be programmed to continue to avoid absorbing unnecessary current from the battery pack. Due to GPIOs, the device also provides the possibility of operating distributed battery temperature sensing via external ntc resistors. In general, gpio can be used to perform absolute voltage and differential voltage conversion. They can also be configured as digital inputs/outputs. The IC supports up to 7 ntcs. The external microcontroller can communicate with L9963E via SPI protocol, which depends on the state of one pin (SPIEN pin) during startup.

     The physical layer can be a classic 4-wire SPI or a 2-wire isolation interface based on a transformer/capacitor through a dedicated isolation transceiver. The L9963E can actually be used as a transceiver, serving as a bridge between the two physical layers. If there are multiple L9963Es arranged vertically, each L9963E communicates with other L9963Es through the vertical isolation interface. The microcontroller can address a single device on the chain or send a broadcast command.

     The L9963E has been designed to perform automatic verification of any faults involving the battery or the entire battery pack. The device can detect a loss of connection to the cell or GPIO terminal. In addition, it features hardware self-test (HWSC) to verify the correct function of the internal analog comparator and adc. All of these checks are performed automatically in case a fault involving the battery or battery pack is detected so as to always provide reliable information to the external microcontroller. The current sensing interface for coulomb counting is also capable of detecting faults such as open and overcurrent in sleep mode. Conversion to Coulomb counts is verified by built-in self-check accuracy and detection of any counter overflows.

     The battery balance terminal can detect any short/on faults and mos protected overcurrent of the internal power supply. The stacking voltage of OV/UV is monitored by three parallel independent systems. They are designed to protect IC from AMR violations, detect any overvoltage events based on LV 148, and offer the possibility of adjusting OV/UV levels based on application and total battery count. In addition, all internal regulators are equipped with UV/OV detection circuits, which are also self-verified by HWSC fault detection. Ground damage detection has also been carried out. Hot shutdown protects IC in case of overtemperature. gpio is able to detect "card @" faults when used as a digital output.

     Communication integrity is ensured by CRC verification, while trim and calibration data are constantly checked for damage. Protocol errors such as incorrect addresses, inconsistent frames and communication interruptions will be detected. The critical failure mode will trigger a dedicated FAULT line (implemented via two gpio) that travels through the L9963E chain via an external optical coupler and reaches the microcontroller. The L9963E ensures the integrity of the FAULT line through heartbeat routines.