linear technology corporation - hope.com.t ltc6804 presentation.pdf · linear technology...
TRANSCRIPT
Linear Technology CorporationLTC6804 Next Generation Battery Stack Monitor
LTC68202-wire Isolated Data Communications
© 2006 Linear Technology
2
Agenda
Background
o High Voltage Battery Stack Applicationso Transportation (hybrid & electric cars, buses, trucks, bicycles, submarines …)
o Portable Power (medical equipment, robotics, data acquisition, communications …)
o Auxiliary Power (uninterruptible power, backup power, wind/solar power storage…)
o Battery Management Electronicso Linear Technology’s Experience
LTC6804 / LTC6820
o Overview of LTC6804o Overview of LTC6820o Functional Safetyo Conclusion
© 2006 Linear Technology
3
Battery Stack Challenges
BMS IC Requirements
System RequirementsHigh Capacity
Accurate Measurements
High Efficiency
Modular
Detectable Errors Long Life
Reliable Communication BalancingFault Detection
Harsh Environment:
• High Voltage
• Wide Temperature
• EMI
Goal: Longer Driving Range at Low Cost, and Highest Safety and Reliability
© 2006 Linear Technology
4
The Challenge for the Electronics
Estimate State of Charge for Each Cell
o Very Accurately Measure Each Cell Voltageo Correlate Current and Voltage Measurements
Control the State-of-Charge for Each Cell
o Control Charge / Dischargeo Balance (Add / Remove Charge)
Ensure Safety
© 2006 Linear Technology
5
Leadership from Linear Technology
LTC6802: Introduced September 2008First Integrated High Voltage Battery Monitor
o EDN, 2008”Innovation Award Finalist”
o Electronic Products, 2008 “Power Semiconductors Product of the Year”
o Elektronik, 2008 “Power Product of the Year ”
o En-Genius Network, 2009 “Battery Management Product of the Year”
o Electronics Weekly Elektra Award, 2009“Semiconductor Product of the Year”
LTC6803: Introduced February 20112nd Generation High Voltage Battery Monitor
o Electronic Design Magazine. 2011 “Best Electronic Design, Automotive”
o 2011 EEPW Editor’s Choice Awards, 2011“Best Analog Product”
o 2012 UBM Electronics ACE Award, 2012“Ultimate Product, Power”
Leveraging 30 Years of High Performance Analog Expertise
o Precision, Ultra-Stable Voltage References
o Precision ADCs
o Amplifiers
o Filters
o Multiplexers
© 2006 Linear Technology
6
Introducing the LTC6804
LTC6804 Highlightso Measures 12 Battery Cells (LiIon, NiMh, Supercap)
o Stackable for Very High Voltage Systems
o Industry Leading Accuracy: 0.04% Error Max
o 16-Bit Resolution
o 290μs to Measure All Cells
o Built-In isoSPI™ Interface:
o Uses a Single Twisted Pair
o 1Mb Isolated Serial Communications
o Up to 100 Meters
o Synchronized Voltage and Current Measurement
o Active and Passive Cell Balancing Control
o 4μA Sleep Mode Supply Current
o General Use I/O
Safety and Reliability Featureso Tolerates Voltages Up to 75Vo Fully Specified from -40°C to 125°Co Includes Comprehensive Self Testso Engineered for ISO26262 Systems
© 2006 Linear Technology
7
Measurement Accuracy
Source: A123 LiPo Cell Datasheet
Typical Operating Range
Very Flat Discharge Curveo When is Battery Fully Charged?o How Much Energy is Left?o When are the Cells Balanced
Sources of Measurement Error
o Today’s Battery Monitor: Typically >50% of Error Attributed to the Voltage Reference Typical Sources of Measurement Error
© 2006 Linear Technology
8
The Buried Zener Advantage
Buried Zener Technology – The Best Choice for Precision Instrumentation
o Low-Temp Drift, High-Temp Operation: 3ppm/°Co Low Thermal Hysteresis or Assembly shift:
100ppm After 260°C Soldero Excellent Long Term Stability for 15 year operation
(25ppm/√khr)
The Challenge: A Voltage Reference that is…o Constant with Temperatureo Constant with Timeo Constant Before, During, and After Board Assemblyo Insensitive to Board Flex and Vibrationo Insensitive to Humidity
LTC6804 Measurement Error vs. Temperature
© 2006 Linear Technology
9
LTC6804 ADC
16Bit Precisiono 100uV LSB – Quantization Error Insignificanto Specified Range: 0V to 5Vo Synchronize External Signals with Cell Measurementso 6 ADC Speeds from 26Hz to 27kHzo All Cells in the System Measurable within 290useco Built-In 3rd Order Noise Filter
ADCMode
–3dBFilter Bandwidth
Conversion Time(All 12-cells)
27kHz 27kHz 290usec14kHz 13.5kHz 465usec7kHz 6.8kHz 814usec3kHz 3.4kHz 1512usec2kHz 1.7kHz 2908usec26Hz 26Hz 178,850usec
© 2006 Linear Technology
10
The Delta-Sigma Advantage
SAR Filter Response1usec Conversion
Averaging 8 Samples
LTC6802/3 Filter Response
Delta Sigma with SINC2 FIR
LTC6804 Filter Response
Delta Sigma with SINC3 FIR
6 Programmable ADC Speeds, Filter Settings
Noise: A Real-World Issueo Sample and Average not Very Effectiveo Impractical to Add High Order Filter on Each Cello RC Filter Limits Bandwidth, Creates I*R Input Error
© 2006 Linear Technology
11
Cell Balancing Features
Passive Balancingo Internal MOSFETs for Low Current Balancingo Control External MOSFETs for High Current Balancingo Programmable Balance Time (Even in Standby Mode): 30min to 2hrs
Active Balancingo New Active Balancing ICs Controllable with an LTC6804 (Using GPIO in SPI Mode)
LTC3300: Bidirectional Active Balancing Controlled with the LTC6804 SPI Interface
© 2006 Linear Technology
12
The isoSPI Advantage
An Elegant Solutiono RF Immuneo Simpleo Low System Cost
Replaceso Isolationo Translationo Transmission
© 2006 Linear Technology
13
Introducing the LTC6820
LTC6820 Highlightso 1Mbps Isolated SPI Data Communicationso Galvanic Isolation Using Simple Transformerso Bidirectional Interface Over a Single Twisted
Pairo Supports Cable Lengths Up to 100 Meterso Very Low EMI Susceptibility and Emissionso Configurable for High Noise Immunity or Low
Powero Requires No Software Changes in Most
Systemso Ultralow, 2μA Idle Currento Automatic Wake-Up Detectiono 2.7V to 5.5V Power Supplyo 16-Lead QFN and MSOP Packages
Safety and Reliability Featureso Fully Specified from -40°C to 125°Co Engineered for ISO26262 Systems
© 2006 Linear Technology
14
isoSPI RF Immunity
isoSPI BCI Test Results:
No Errors with 200mA of RF Injection and isoSPI Operating with 20mA Signal Strength
© 2006 Linear Technology
15
Functional Safety
LTC6804: Engineered for ISO26262 Systemso Digital Filter and Memory Self Testso Open Wire Detection between Battery and Monitoro 2nd Internal Reference for ADC Checko MUX Self Test (Ensures All Channel Measured)o Measures C12 to C0: Redundant Measurement Checko Measures Internal Power Supply Voltageso 5 General purpose I/O: Enables Redundant Monitoring via Sensors,
EEPROM, ADCs, or DACs.
Automotive Safety Intrinsic Level (ASIL)o The LTC6804 and LTC6820 can Support Systems Rated up to ASIL D
© 2006 Linear Technology
16
SummaryLeading Edge Performance for Leading Edge Battery Systemso Ability to Precisely Manage Every Cell in a High Voltage Battery Stack
◊ 0. 04% Measurement Error (Max)◊ 290usec Measurement Time for All Cells (Fast Mode)◊ Ability to Synchronize Voltage and Current Measurements◊ Supports both Active Balancing (via SPI) and Passive Balancing (via Switch Control)
o Support for Distributed, Modular Designs◊ Robust RF Immune Link via isoSPI;, Modules can be Distributed Over Long Distances◊ Local EEPROM can accessed by each LTC6804 for Module Specific Data, such as Calibration◊ 4uA Sleep Mode Enables Long Term Pack Storage
o High Reliability & Robust Operation◊ Engineered for ISO 26262 Compliant Systems◊ Includes Comprehensive Self-Testing◊ Inherent Noise Filtering with 6 Speed / Filter Settings◊ Long Term Stability Assured with Buried Zener Technology◊ Withstands Voltages up to 75V◊ Specified for Operation from -40°C to 125°C