Battery stack monitor achieves 0.04% measurement accuracy

19th November 2015

Nat Bowers

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Datasheet

A drop-in replacement for the LTC6804, Linear Technology has announced the LTC6811 high voltage battery stack monitor featuring higher performance and 25% lower price. This a complete battery measuring IC for EVs and HEVs that incorporates a deep buried Zener voltage reference, high voltage multiplexers, 16-bit delta-sigma ADCs and a 1Mb/s isolated serial interface.

An LTC6811 can measure up to 12 series-connected battery cell voltages with better than 0.04% accuracy. With 8 programmable 3^r^d order low pass filter settings, the LTC6811 provides outstanding noise reduction. In the fastest ADC mode, all cells can be measured within 290µs.

For large battery packs, multiple LTC6811s can be interconnected and operated simultaneously, using Linear Technology’s proprietary 2-wire isoSPI interface. This built-in interface provides electrically isolated, high RF noise immune communication for data rates up to 1Mb/s. Using twisted pair, many LTC6811s can be connected in a daisy chain to one host processor, enabling the measurement of hundreds of cells in high voltage battery stacks.

The LTC6811 follows three generations of road-proven battery monitor ICs, designed to surpass the environmental, reliability and safety demands of automotive and industrial applications. The LTC6811 is fully specified for operation from -40 to +125°C. It has been engineered for ISO 26262 (ASIL) compliant systems with extensive fault coverage via its redundant voltage reference, logic test circuitry, cross-channel testing, open wire detection capability, a watchdog timer and packet error checking on the serial interface.

For existing designs using Linear Technology’s LTC6804 battery stack monitor, the LTC6811 is a drop-in replacement with additional filter cutoff frequencies, added passive and active balancing control features, new ADC commands and enhanced fault coverage for functional safety. The LTC6811 is fully supported by Linear’s Linduino technology, an Arduino-based MCU board and software library. The MCU board includes an electrically isolated USB port and directly connects to the LTC6811 demonstration board, providing a simple platform for evaluating and developing the LTC6811.

The LTC6811 is offered in a small 8x12mm surface mount SSOP package. Priced at $8.19 each in 1,000 unit quantities, samples and demonstration boards are now available.