Atmel - Safe Battery Management Solution for Automotive and Industrial High-cell-count Li-Ion Battery Packs

The ATA6870/71 chipset requires less external components than comparable solutions because it includes a hot plug-in capability, six integrated AD converters with a cut-off frequency lower than 30 Hz, saving external filters, and a stackable microcontroller power supply. With Atmel's cost-efficient 30-V CMOS technology, these features allow cost savings of up to 60 percent, compared to existing solutions.

The ATA6870 is the industry's first battery management IC to include all functionalities required to control a high-cell-count Li-Ion battery including six precise 12-bit AD converters for voltage monitoring, cell balancing, cell temperature measuring, and unique features such as stackable integrated power supply for a microcontroller or hot plug-in capability.

Battery safety and efficiency are key for industrial and automotive battery applications, said Claus Mochel, Automotive High-Voltage Marketing Manager for Atmel Corporation. Atmel's new ATA6870 and ATA6871 address these issues by offering a battery management solution with an unsurpassed safety concept and advanced parallel cell voltage measuring and balancing technique.

Since Li-Ion batteries are very sensitive against overcharging and deep discharge, they may burn or explode. To prevent this, Atmel provides a special safety strategy with its secondary protection device, the ATA6871. This monitors the battery cells' voltage and temperature, and prevents Li-Ion batteries from thermal runaway or exploding. If either of these were to occur in a battery cell, it can then be switched off by the emergency relays. With its implemented self-test routines, which run without an external microcontroller or software and its hardware-implemented monitoring thresholds, the ATA6871 constitutes the highest available safety level for Li-Ion battery monitoring. Proper operation is ensured even if the primary device is damaged.

Both the ATA6870 and the ATA6871 circuits monitor six-battery cells and can be stacked up to 16 times. For the highest communication robustness between the stacked ICs, the ICs feature level shifters based on current sources. The ATA6870 also includes an 8-bit checksum monitor that helps further increase data communication robustness.

The ATA6870 provides a dedicated AD converter for each battery cell to be monitored. This enables simultaneous measurement voltage of all cells within one battery string for precise state-of-charge determination of Li-Ion battery cells.
The integrated power supply for the microcontroller can be stacked the same way as the IC itself. Therefore, the current required to supply the microcontroller can be taken from the top cell and be fed back into the battery string's bottom cell. As a result, the microcontroller's current consumption will not cause any cell imbalance, helping designers save expensive high-voltage devices.