LTC6811-1/LTC6811-2 12-Cell Battery Stack Monitors FEATURES DESCRIPTION n Pin-Compatible Upgrade from the LTC6804 The LTC 6811 is a multicell battery stack monitor that n Measures Up to 12 Battery Cells in Series measures up to 12 series connected battery cells with n 1.2mV Maximum Total Measurement Error a total measurement error of less than 1.2mV. The cell n Stackable Architecture for High Voltage Systems measurement range of 0V to 5V makes the LTC6811 TM n Built-in isoSPI Interface suitable for most battery chemistries. All 12 cells can be n 1Mb Isolated Serial Communications measured in 290s, and lower data acquisition rates can n Uses a Single Twisted Pair, up to 100 Meters be selected for high noise reduction. n Low EMI Susceptibility and Emissions Multiple LTC6811 devices can be connected in series, per- n 290s to Measure All Cells in a System mitting simultaneous cell monitoring of long, high voltage n Synchronized Voltage and Current Measurement battery strings. Each LTC6811 has an isoSPI interface for n 16-Bit ADC with Programmable Noise Filter high speed, RF-immune, long distance communications. n Engineered for ISO 26262-Compliant Systems Using the LTC6811-1, multiple devices are connected in n Passive Cell Balancing with Programmable Timer a daisy chain with one host processor connection for all n 5 General Purpose Digital I/O or Analog Inputs devices. Using the LTC6811-2, multiple devices are con- n Temperature or other Sensor Inputs nected in parallel to the host processor, with each device 2 n Configurable as an I C or SPI master individually addressed. n 4A Sleep Mode Supply Current n The LTC6811 can be powered directly from the battery 48-Lead SSOP Package n stack or from an isolated supply. The LTC6811 includes AEC-Q100 Qualified for Automotive Applications passive balancing for each cell, with individual PWM APPLICATIONS duty cycle control for each cell. Other features include an onboard 5V regulator, five general purpose I/O lines and a n Electric and Hybrid Electric Vehicles sleep mode, where current consumption is reduced to 4A. n Backup Battery Systems All registered trademarks and trademarks are the property of their respective owners. Protected n Grid Energy Storage by U.S. patents, including 8908779, 9182428, 9270133. n High Power Portable Equipment TYPICAL APPLICATION LTC6811 ISO26262 2.0 DIAGNOSTICS REAL WORLD CELL MEASUREMENT BUDGET SWITCH 1.5 ON/OFF 1.0 0.5 16 DATA ADC MUX CELL = 3.3V I/O 0.0 MEASUREMENT ERROR, 25C + 0.5 ADDITIONAL PCB ASSEMBLY SHIFT 1.0 ADDITIONAL VOLTAGE 1.5 CHANGE REFERENCE 40C TO 125C 2.0 68111 TA01b 68111 TA01a SENSORS Rev. C 1 Document Feedback For more information www.analog.com MEASUREMENT ERROR (mV)LTC6811-1/LTC6811-2 TABLE OF CONTENTS Features ............................................................................................................................ 1 Applications ....................................................................................................................... 1 Typical Application ............................................................................................................... 1 Description......................................................................................................................... 1 Absolute Maximum Ratings ..................................................................................................... 3 Pin Configuration ................................................................................................................. 3 Order Information ................................................................................................................. 4 Electrical Characteristics ........................................................................................................ 4 Typical Performance Characteristics .........................................................................................10 Pin Functions .....................................................................................................................16 Block Diagram ....................................................................................................................17 Differences Between the LTC6804 and the LTC6811 .......................................................................19 Operation..........................................................................................................................20 State Diagram ....................................................................................................................................................... 20 Core LTC6811 State Descriptions ......................................................................................................................... 20 isoSPI State Descriptions ..................................................................................................................................... 21 Power Consumption ............................................................................................................................................. 21 ADC Operation ...................................................................................................................................................... 22 Data Acquisition System Diagnostics ................................................................................................................... 29 Watchdog and Discharge Timer ............................................................................................................................ 35 Reset Behaviors .................................................................................................................................................... 37 S Pin Pulse Width Modulation for Cell Balancing .................................................................................................. 38 2 I C/SPI Master on LTC6811 Using GPIOs............................................................................................................. 39 S Pin Pulsing Using the S Control Register Group ................................................................................................ 43 Serial Interface Overview ...................................................................................................................................... 44 4-Wire Serial Peripheral Interface (SPI) Physical Layer ........................................................................................ 44 2-Wire Isolated Interface (isoSPI) Physical Layer ................................................................................................. 45 Data Link Layer ..................................................................................................................................................... 52 Network Layer ....................................................................................................................................................... 53 Applications Information .......................................................................................................67 Providing DC Power .............................................................................................................................................. 67 Internal Protection and Filtering ............................................................................................................................ 69 Cell Balancing ....................................................................................................................................................... 71 Discharge Control During Cell Measurements ...................................................................................................... 73 Digital Communications ........................................................................................................................................ 75 Enhanced Applications .......................................................................................................................................... 86 Reading External Temperature Probes .................................................................................................................. 89 Package Description ............................................................................................................90 Revision History .................................................................................................................91 Typical Application ..............................................................................................................92 Related Parts .....................................................................................................................92 Rev. C 2 For more information www.analog.com