Features and Benefits
- Measures Up to 15 Battery Cells in Series
- 2.2mV Maximum Total Measurement Error
- Stackable Architecture Supports 100s of Cells
- Built-In isoSPI™ Interface
- 1Mb Isolated Serial Communications
- Uses a Single Twisted Pair, Up to 100 Meters
- Low EMI Susceptibility and Emissions
- Bidirectional for Broken Wire Protection
- 245µs to Measure All Cells in a System
- Synchronized Voltage and Current Measurement
- 16-Bit Delta-Sigma ADC with Programmable 3rd Order Noise Filter
- Engineered for ISO 26262-Compliant Systems
- Passive Cell Balancing Up to 200mA (Max) with Programmable Pulse-Width Modulation
- 9 General Purpose Digital I/O or Analog Inputs
- Temperature or Other Sensor Inputs
- Configurable as an I2C or SPI Master
- 6µA Sleep Mode Supply Current
- 64-Lead eLQFP Package
The LTC6812-1 is a multicell battery stack monitor that measures up to 15 series connected battery cells with a total measurement error of less than 2.2mV. The cell measurement range of 0V to 5V makes the LTC6812-1 suitable for most battery chemistries. All 15 cells can be measured in 245µs, and lower data acquisition rates can be selected for high noise reduction.
Multiple LTC6812-1 devices can be connected in series, permitting simultaneous cell monitoring of long, high voltage battery strings. Each LTC6812-1 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 LTC6812-1 can be powered directly from the battery stack or from an isolated supply. The LTC6812-1 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.
- Electric and Hybrid Electric Vehicles
- Backup Battery Systems
- Grid Energy Storage
- High Power Portable Equipment
Product Lifecycle Production
At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.
Evaluation Kits (2)
Demonstration circuit DC2792A is an SPI serial to dual-port isoSPI adapter that uses a pair of multiplexed LTC6820 isoSPI transceivers. The board can replace a DC1941 in cases where isoSPI battery-management (BMS) devices are being evaluated, but provides a second isoSPI master to exercise the reversible isoSPI feature where available.
The SPI interface can be provided via the legacy 14-contact ribbon cable from either a DC590 or DC2026 USB adapter, or directly installed on the DC2026 as a Linduino ‘shield’. The two isoSPI ports are MAIN and AUXiliary, with activity of each indicated by blue LEDs.
Demonstration circuit 2350A is a multicell battery stack monitor featuring the LTC6812-1, a 15-cell monitor on the DC2350A-A, or the LTC6813-1, an 18-cell monitor on the DC2350A-B. Multiple boards can be linked through a 2-wire isolated serial interface (isoSPI) to monitor any number of cells in a stack. The demo circuit also features reversible isoSPI enabling a fully redundant communication path.
The DC2350 can communicate to a PC by connecting directly to a DC2026 Linduino® One. The DC2026 must be loaded with the appropriate program (called a “sketch”) to control the battery stack monitor IC and receive data through a USB serial port. The DC2792/DC1941 can be connected to the DC2026 to provide a fully isolated isoSPI interface to the DC2350.
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Sample & Buy
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