Issue link: https://resources.mouser.com/i/1437660
7 Saving Power for the Future | ADI and safety, as it's designed to work in different, harsh environments and is compliant to various functional safety standards, from the Automotive ASIL to Industrial SIL (for example, VDE AR 2510-2/-50, IEC EN 61508, and others). One new and unique solution for having the most efficient and reliable battery monitoring system involves the combination of an 18-cell monitor and balance IC with a microcontroller to SPI slave isolated interface. As seen in Figure 4, a multicell battery stack monitor measures up to 18 series connected battery cells with a total measurement error of less than 2.2mV. The cell measurement range of 0V to 5V makes it suitable for most battery chemistries. All 18 cells can be measured in 290μs, and lower data acquisition rates can be selected for high noise reduction. Multiple stack monitor devices can be connected in series, permitting simultaneous cell monitoring of long, high-voltage battery strings. Each stack monitor has an isoSPI™ interface for high speed, RF immune, long-distance communications. Multiple devices are connected in a daisy chain with one host processor connection for all devices. This daisy chain can be operated bidirectionally, ensuring communication integrity, even in the event of a fault along the communication path. The IC can be powered directly from the battery stack or from an isolated supply. The IC includes passive balancing for each cell, with individual PWM duty cycle control for each cell. Other features include an onboard 5V regulator, nine general-purpose I/O lines, and a sleep mode where current consumption is reduced to 6μA. Due to the short- and long-term accuracy demands of the BMS application, it uses a buried Zener conversion reference rather than a band gap reference. This provides a stable, low drift (20ppm/√kHr), low temperature coefficient (3ppm/°C), low hysteresis (20ppm) primary voltage reference along with excellent long-term stability. This accuracy and stability is critical since it is the basis for all subsequent battery cell measurements, and these errors have a cumulative impact on acquired data credibility, algorithm consistency, and system performance. Although a high accuracy reference is a necessary feature to ensure superior performance, that alone is not enough. The analog-to-digital converter architecture and its operation must meet specifications in an electrically noisy environment, which is the result of the pulse- width modulated (PWM) transients of the system's high current/ voltage inverter. Accurate assessment of the state of charge and health of the batteries also requires correlated voltage, current, and temperature measurements. LTC6812 15-Channel Multi-Cell Battery Monitor Measures Up to 15 Battery Cells in Series Stackable Architecture Supports 100s of Cells Passive Cell Balancing Up to 200mA (Max) with Programmable Pulse-Width Modulation LTC6813 18-Channel Multi-Cell Battery Monitor Measure up to 18 battery cells in series Total measurement error < 2.2mV 9 general purpose Analog In & Digital I/O, includes open wire detection LEARN MORE LEARN MORE Although a high accuracy reference is a NECESSARY FEATURE to ensure SUPERIOR PERFORMANCE that alone is not enough