Texas Instruments has introduced three new smart battery management ICs that improve measurement and protection of multicell, lithium-based battery packs. They aim to simplify design in multicell lithium-based rechargeable batteries used in uninterruptible power supplies and applications, such as cordless power tools, power-assisted bicycles, and portable medical and test equipment.
The bq78PL114 provides complete lithium battery system control, monitoring and safety functions for 4-series cells. It integrates accurate battery fuel gauge technology with efficient cell balancing, short-circuit detection and battery protection. The device is completely user-configurable with parametric tables set in Flash memory to support a variety of Li-Ion and Li-Polymer chemistries, operating conditions, safety control and data reporting design requirements.
In addition to the controller, the bq76PL102 dual-cell battery monitor performs simultaneous voltage and temperature monitoring of each cell and reports these parameters over a proprietary PowerLAN communications interface. This allows designers to combine multiple bq76PL102 monitor devices with the bq78PL114 controller to create a smart battery solution for up to 12 rechargeable cells. Realtime communications is possible in all operating conditions, even during widely fluctuating load conditions. The scalable PowerLAN architecture also provides robust communications in tough electromagnetic and RF interference situations, while avoiding excess power draw and a large number of discrete components.
Partitioning of the battery monitoring function cell-by-cell enables a more accurate state of charge measurement. With this in mind, the bq78PL114-based system helps extend battery life and system runtime with TI’s patented PowerPump cell balancing technology. This technology uses a charge-transfer methodology that does not waste excess energy as heat, but moves energy efficiently and dynamically from cell to cell. Precise balancing occurs at every stage of operation – at charge, discharge and rest. With PowerPump technology, cell balancing is automatically coordinated between all cells in the system.
Also new is a device integrating safety and protection for multicell applications with a new lithium-based battery protector and analog front end for 5- to 10-cell battery systems. The bq77PL900, which includes an I²C interface for communication with a host controller, can also operate as a standalone battery protection circuit. The device integrates a 5 V and a 3,3 V LDO to help power the host controller or other circuits in the system.
The low-power battery protection circuit includes a voltage translation system to measure temperature, system current and individual cell voltages. Cell balancing can be performed through bypassing current around selected cells. The bq77PL900 also provides full safety protection for over-voltage, under-voltage, over-temperature and over-current in discharge and short circuit during discharge conditions.
For more information contact EBV Electrolink, +27 (0)21 402 1940, [email protected], www.ebv.com
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