LTC6802多芯锂离子电池电压监控与均衡电路介绍

1、Multi-Cell Battery MonitorThe LTC6802is designed to quickly and accurately measure the The LTC6802 is designed to quickly and accurately measure the voltage on each cell in a long battery stringBasic FunctionalityMeasures each cell voltage(<025% E(<0.25% ErrorStackable architectureThe LTC68021

2、: Serial interfaceThe LTC6802-1: Serial interfaceThe LTC6802-2: Parallel interfaceAll cells in a stack measured within 13msAll cells in a stack measured within 13ms.Under voltage and over voltage monitored for each cellEach cell has a MOSFET switch which can be used todischarge over-charged cells.LT

3、C6802:Multi Cell Battery Stack Monitor LTC6802: Multi-Cell Battery Stack Monitor LTC6802Features and Benefits LTC6802 Features and BenefitsE h IC M i f 412 Each IC can Monitor from 4 to 12 Individual CellsStackable Architecture Allows Monitoring 1000s of Volts On-chip passive balancing switchesProvi

4、sion for off-chip passive balancinggNo Optocouplers or Digital IsolatorsRequired between PacksOpen-wire fault detection UV/OV monitor modeOn-Chip ADC and Precision Reference Self test modes2thermistor inputs plus on-chipUnder-voltage and Over-voltage Detection<10mV MAX error from -40°C to 85

5、°C 2 thermistor inputs plus onchip temperature sensor2 General Purpose I/O lines13mSec cell voltage acquisition time for all cells in an entire stack 1mA continuous, 50uA standbyfor all cells in an entire stack 1MHz SPI interfaceAccuracy Specifications Accuracy Specifications Supply Specificati

6、ons Supply Specifications Block DiagramsLTC6802-1LTC6802-2LTC68021Daisy Chain SPILTC68022 Addressable SPI© 2007Linear Technology Confidential Information The 6802Uses a “daisy chain” serial connection connection. © 2007Linear Technology Confidential Information 2Choices for 2 Choices for S

7、erial InterfaceThe 68022uses The 6802-2uses an addressable isolated serial ti connection © 2007Linear Technology Confidential Information © 2007Linear Technology Confidential Information UV < All Cells < OV OPEN WIRE DETECTION OPEN WIRE DETECTIONInternal current sources can be used t

8、o Internal current sources can be used to determine if the wire is truly open. For example, an open on input C3 will result in a near zero reading for both ll t d t C3F ill t ti cells connected to C3. For illustration these cells are labeled B3 and B4 in the figure below. If a near zero reading is e

9、ncountered for B3and B4, the MPU is encountered for B3 and B4, the MPU can command the LTC6802 to place 100µA current sources from the ADC inputs to V. If input C3 is open, the di ill h B3t b new reading will show B3 to be zero and B4 to be full scale. © 2007Linear Technology Confidential

10、Information Cell Voltage FilteringCell Voltage FilteringThe delta-sigma ADC inside the 6802has a “built-in” filter. The noise bandwidth is equivalent to an 850Hz RC filter yetthe conversion rate is still 1KSPS. Thismakes the 6802 superior to SAR ADCs Additional external filtering is possible. An ext

11、ernal discharge MOSFET is recommended. FMEA Internal diodes inside the IC protect against open circuits between the IC and the battery cells. This includes the connecting/disconnecting of a harness, resulting in a random order of connections to LTC6802 inputs. Loss of daisy chain communication will

12、if V V i i i (68021l d l h 68022 occur if V+ or V-is an open circuit (6802-1 only, does not apply to the 6802-2.There is no effect on the LTC68022if theThere is no effect on the LTC6802-2 if the serial port is isolated. For the LTC6802-1 external isolation diodes between ICs protect voltages A redun

13、dant load path is required voltages. A redundant load path is requiredvoltages- FMEAAn open with in a group of cells will create a low impedance high voltage across the LTC6802 inputs. This will damage the LTC6802 unless external protection circuits are added. A Schottky diode will protect against r

14、everse voltages. An SCR will protect against forward voltage against forward voltage- LTC6802S h d l LTC6802 ScheduleSamplesDemo-boardPC Evaluation SystemPC Evaluation SystemDetailed Datasheet and Application InformationFixes bugs with 1st SiliconLower Standby CurrentBuilt in Self Test ModesAddition

15、al commandsLTC6802D B d LTC6802 Demo-Boards Complete Circuitry for Monitoring & Discharging up to 12 cells Stackable for any number of cellsStackable for any number of cellsDC1331 (Daisy Chained Serial I/O DC1393 (Parallel I/O Direct Connection to a PC via the DC590 (SPI to USB Interface Extensi

16、ve Graphical User Interface (GUIforExtensive Graphical User Interface (GUI for Demonstration of Features & Code Development Click-button Implementation of LTC6802 Commands Set-screw Connector for Easy Wiring HarnessDevelopment to Connect CellsD b d C fi tiDemo-board Configuration Graphical User

17、Interface (Shown Here Monitoring 10DC1331BoardsColor coded status 10 DC1331 Boards Color coded status of all 120 cellsDetailed status of board #6 board #6DC1331Schematic DC1331 Schematic DC1393A for LTC6802-2Isolated Battery Monitor DC1393A for LTC68022 Isolated Battery Monitor Isolated, addressed S

18、PI busing Measures 5 to 12 cells per IC 0.25% accuracy, 1ms per channel SPI communication or stand-aloneOn board charge balancing On-board charge-balancing resistors and FET drivers LED visual indications of charge-b l i i ibalancing activity Dedicated GUI for use with DC590: 03242008_LTC6802-2_MINI

19、_GUI_XLS_OUT_V_02_1.exe External 5V powers all isolators April 2008 FAE Meeting Jon Munson -Signal ConditioningGUI for DC1393A Battery Stack Monitor: GUI for DC1393A Battery Stack Monitor: 03242008_LTC6802-2_MINI_GUI_XLS_OUT_V_02_1.exe S t t 10DC1393A Supports up to 10 DC1393A All functions are “poi

20、nt and click” Visual status of up to 120cellsVisual status of up to 120 cells color-coded array OV, UV, balance ctrlsFull numeric readouts and Full numeric readouts andcontrols for any selectedLTC6802-2: Cell voltages Temperature data Cell-discharge control GPIO control Register transmissions inhexa

21、decimalApril 2008 FAE Meeting Jon Munson -Signal ConditioningOpto-Isolation for High-Speed SPI Opto Isolation for HighSpeed SPI(LTC6802-2 shown Supports full 1Mbps trafficOpto power furnished externally Opto power furnished externally No extra battery load in idleDC/DC for isolated Vlogic Included i

22、n DC1393A Included in DC1393AApril 2008 FAE Meeting Jon Munson -Signal ConditioningOperation with Fuel Cells or UltraCapacitors Operation with Fuel Cells or UltraCapacitors Make isolated Vlogic a virtual minus supplyg Sacrifice ADC ch1 for enhanced Vcm range Supports 11 very low cell voltagesApril 2008 FAE Meeting Jon Munson -Signal ConditioningOperation