STEVAL-BMS114TX

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Battery management system module based on L99BM114 and L99BM1T

概要

The STEVAL-BMS114TX is a battery management system (BMS) evaluation board that manages from 4 to 14 battery cells.

The main advantage of this evaluation board is ensuring isolated connection to an external MCU, thanks to the embedded transceiver.

The board is based on the L99BM114 Li-ion battery monitoring and protection chip for high-reliability applications and the L99BM1T general-purpose SPI to isolated SPI bidirectional transceiver.

The main activity of the L99BM114 is monitoring the cells and battery node status through stack voltage measurement, cell voltage measurement, temperature measurement, and coulomb counting.

Measurement and diagnostic tasks can be executed either on demand or periodically, with a programmable cycle interval.

Measurement data are available for an external microcontroller to perform charge balancing and to compute the state of charge (SOC) and the state of health (SOH).

The L99BM1T general-purpose SPI to isolated SPI bidirectional transceiver can transfer communication data incoming from a classical 4-wire based SPI interface to a 2-wire isolated interface (and vice versa). In our board, the transceiver is configured as a slave.

The STEVAL-BMS114TX provides an elaborate monitoring network to sense the voltage of each cell. It is possible to sense the current of the entire battery pack.

Passive cell balancing can be performed either via the L99BM114 internal MOSFETs or via external MOSFETs. The controller can either manually control the balancing drivers or start a balancing task with a fixed duration. In the second case, the balancing may be programmed to continue even when the IC enters a low-power mode called silent balancing, to avoid unnecessary current absorption from the battery pack. The balancing function is necessary to lengthen the battery capacity and its duration.