Automotive battery stack monitor achieves 0.04% measurement accuracy

November 18, 2015 // By Julien Happich
Linear Technology's LTC6811 is a high voltage battery stack monitor designed as a drop-in replacement for the LTC6804 with higher performance and 25% lower price.

The LTC6811 is a complete battery measuring IC for hybrid/electric vehicles that incorporates a deep buried Zener voltage reference, high voltage multiplexers, 16-bit delta-sigma ADCs and a 1Mbps isolated serial interface. An LTC6811 can measure up to 12 series-connected battery cell voltages with better than 0.04% accuracy. With 8 programmable 3rd order low pass filter settings, the LTC6811 provides outstanding noise reduction. In the fastest ADC mode, all cells can be measured within 290µsec.

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 1Mbps. 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 IC is fully specified for operation from ˗40°C to 125°C and features 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. It comes in a 8x12mm surface mount SSOP package.

Visit Linear Technology at www.linear.com/product/LTC6811