Linear Technology announces the LTC6802^®, a highly integrated multicell battery monitoring IC capable of measuring up to 12 individual battery cells. Using a novel stacking technique, multiple LTC6802s can be stacked in series without opto-couplers or isolators, allowing precision voltage monitoring of every cell in long strings of series connected batteries. Long battery strings enable high power, rechargeable battery applications, such as electric & hybrid electric vehicles, scooters, motorcycles, golf carts, wheelchairs, boats, submarines, forklifts, robotics and portable medical equipment. 

The LTC6802-1 is a complete battery monitoring IC that includes a 12-bit ADC, a precision voltage reference, a high voltage input multiplexer and a serial interface. Each LTC6802-1 can measure up to 12 series connected battery cells with an input common mode voltage up to 60V. In addition, multiple LTC6802-1 devices can be placed in series to monitor the voltage of each cell in a long battery string. The unique level-shifting serial interface allows the serial ports of these devices to be daisy-chained without optocouplers or isolators. 

When multiple LTC6802-1 devices are connected in series they can operate simultaneously, permitting all cell voltages in the stack to be measured within 13ms. To minimize power, the LTC6802-1 offers a measure mode, which simply monitors each cell for overvoltage and undervoltage conditions. A standby mode is also provided. Each cell input has an associated MOSFET switch for discharging overcharged cells. For large battery stack applications requiring individually addressable serial communications, see the LTC6802-2. 

The maximum total measurement error is guaranteed to be less than 0.25% from -40°C to 85°C and every cell voltage in a battery stack can be measured within 13ms. Each cell is monitored for under voltage and over voltage conditions and an associated MOSFET switch is available to discharge over-charged cells. Each LTC6802 communicates via a 1MHz serial interface. Also included are temperature sensor inputs, GPIO lines and a precision voltage reference. The LTC6802 is a small 8mm x 12mm surface mount device. The combined robustness, exceptional precision and tiny package directly addresses the critical requirements of emerging and advanced battery technologies. 

Features

• Measures up to 12 Li-Ion Cells in Series (60V Max)
• Stackable Architecture Enables >1000V Systems
• 0.25% Maximum Total Measurement Error
• 13ms to Measure All Cells in a System
• Cell Balancing:
  • On-Chip Passive Cell Balancing Switches
  • Provision for Off-Chip Passive Balancing
• Two Thermistor Inputs Plus On-Board
• Temperature Sensor
• 1MHz Daisy-Chainable Serial Interface
• High EMI Immunity
• Delta Sigma Converter with Built-In Noise Filter
• Open Wire Connection Fault Detection
• Low Power Modes
• 44-Lead SSOP Package 

Applications

• Electric and Hybrid Electric Vehicles
• High Power Portable Equipment
• Backup Battery Systems
• High Voltage Data Acquisition Systems