Chip family protects Li-ion batteries in vehicles and power tools

June 04, 2012 // By Christoph Hammerschmidt
Rohm Semiconductor introduces a line-up of ICs providing all functions needed for controlling, monitoring and protecting systems using multiple-cell series-connected Li-ion battery packs. These rechargeable battery packs are commonly used in hybrid electric vehicles or electric vehicles (HEV/EV), Power Tools and E-Bicycles, application areas which are expected to rapidly grow over the next few years.

Li-ion batteries have proven to be an efficient high performance power source; however, safety functions such as voltage monitoring, over-/overdischarge detection, cell balancing and temperate measuring play a crucial role in order to secure stable and safe operation. Rohm provides a portfolio of different families addressing the needs of the respective target applications, further offering chipsets for complete multiple-cell control and protection solutions.

These are low consumption current protector ICs compatible with multiple-cell series-connected Li-ion battery packs (five to ten respectively 13 cells), detecting the over-charge or over-discharge and over-current of each cell. They also integrate the Gate driver for an automatic ON/OFF control of the external PMOS-FET or N-ch FET (depending on the version) for the charge and discharge. Based on the results of the voltage control of each cell or the entire battery pack, as well as the monitoring of the charge and discharge current, an external MCU can perform corresponding actions to protect the batteries and to prevent the system to get into an irregular state. For a complete protection solution, Rohm also offers the MCU ML5227 which can be used in combination with the battery monitoring IC. The monitoring IC can supply 3.3V power supply to the MCU so that no external voltage regulator is needed. The MCU is an 8bit high-performance controller based on the low power Microcontroller series ML610Q4xx with integrated Flash memory to store the register settings. With these chip-sets of MCU and monitoring IC Rohm offers a highly efficient solution for multiple cell Li-Ion battery packs which can be adopted to various systems according to the customer's needs.

The ML5218 is a Li-ion battery monitoring IC for packs of four to 14 cells especially designed for the use in automotive applications. It features a highly accurate voltage measurement function to detect overcharge/over-discharge, passive cell balancing and the possibility of four temperature measurements with externally connected sensors.

In addition the IC also includes