8-Channel, Li-Ion, Battery Monitoring System Data Sheet AD7284 FEATURES FUNCTIONAL BLOCK DIAGRAM V DD CB1 TO CB8 8 analog input channels, integrated secondary monitor 3 mV maximum cell voltage accuracy, TUE, 14-bit ADC CELL BALANCE DAISY-CHAIN D UP Very low measurement latency across 96 cells INTERFACE INTERFACE D UP Stack voltage measurement TEMP 16 mV typical battery stack voltage (TUE) accuracy 5V REG V VPIN0 TO VPIN8 REG5 + Cell balancing interface, with individually programmable MUX ADC AV CC VPAUX1 TO VPAUX4 DV on time CC V REFBUF V DRIVE 4 auxiliary analog input channels, 14-bit ADC REF1 V CLK1 REF1 CONTROL GPOP1 Suitable for thermistor inputs and external diagnostics LOGIC GPOP2 REFGND1/REFGND2 REGISTERS MASTER Buffered reference output for ratiometric measurements AND TIMERS RESET CLK2 V REF2 REF2 Internal temperature sensor V operating range: 10 V to 40 V DD SCLK MUX On-chip 5 V regulator VSIN0 TO VSIN8 ADC SDI SPI INTERFACE SDO Watchdog timer CS I matching current: 100 A DD C CM Robust, proprietary daisy-chain interface AD7284 D DWN DAISY-CHAIN INTERFACE D DWN SPI to host controller CRC protection on read and write commands V AGND1/ DGND SS AGND2 2 general-purpose outputs Figure 1. 64-lead low profile quad flat package, exposed pad (LQFP EP) Junction temperature range: 30C to +120C Qualified for automotive applications APPLICATIONS Li-Ion battery monitoring Electric and hybrid electric vehicles Stationary power applications GENERAL DESCRIPTION The AD7284 contains all the functions required for the general- There are two on-chip 2.5 V voltage references: one reference purpose monitoring of stacked Li-Ion batteries, as used in for the primary measurement path, and one for the secondary hybrid electric vehicles and battery backup applications. measurement path. The AD7284 has multiplexed cell voltage and auxiliary, analog- The AD7284 operates from one VDD supply, ranging from 10 V to-digital converter (ADC) measurement channels supporting to 40 V. The device provides eight differential analog input four to eight cells of battery management. The device provides a channels to accommodate large common-mode signals across maximum total unadjusted error, TUE, (cell voltage accuracy) of the full V range. Each channel allows an input signal range, DD 3 mV that includes all the internal errors from input to VPINx VPIN(x 1) and VSINx VSIN(x 1), of 0 V to 5 V, output. The primary ADC resolution is 14 bits. where x = 0 to 8. The input pins assume a series stack of eight cells. The AD7284 includes four auxiliary ADC input channels The AD7284 also includes an integrated secondary measurement that can be used for temperature measurement or system path that validates the data on the primary ADC. Other diagnostic diagnostics. features include the detection of open inputs, communication, and power supply related faults. The AD7284 has a differential daisy-chain interface that allows multiple devices to be stacked without the need for individual The AD7284 cell balancing interface outputs control the device isolation. By design, this interface allows both device external field effect transistors (FETs) to allow discharging of to device communication within the same module and individual cells. communication between devices on different modules. Rev. C Document Feedback Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. rights of third parties that may result from its use. Specifications subject to change without notice. Tel: 781.329.4700 20172019 Analog Devices, Inc. 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Trademarks and registered trademarks are the property of their respective owners. 14703-001AD7284 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Modes of Operation ................................................................... 25 Applications ....................................................................................... 1 Active Mode, Power-Up ............................................................ 25 Functional Block Diagram .............................................................. 1 Reset ............................................................................................. 26 General Description ......................................................................... 1 Power-Down ............................................................................... 26 Revision History ............................................................................... 2 Watchdog Timer ............................................................................. 28 Specif icat ions ..................................................................................... 3 Serial Peripheral Interface (SPI) ................................................... 29 ADC Timing Specifications ........................................................ 6 Register Write and Register Read Operations ............................ 29 Serial Peripheral Interface (SPI) Timing Specifications .......... 7 Conversion Data Readback Operation .................................... 30 Absolute Maximum Ratings ............................................................ 8 CRC Pseudocode Examples ...................................................... 31 Thermal Data ................................................................................ 8 Daisy-Chain Interface .................................................................... 32 Thermal Resistance ...................................................................... 8 Daisy-Chain Physical Interface ................................................ 32 ESD Caution .................................................................................. 8 Daisy-Chain Protocol ................................................................ 32 Pin Configuration and Function Descriptions ............................. 9 Daisy-Chain Debug Mode ........................................................ 32 Typical Performance Characteristics ........................................... 11 Register Map ................................................................................... 33 Terminology .................................................................................... 14 Page Addressing .......................................................................... 33 Theory of Operation ...................................................................... 15 Page 0 Addresses......................................................................... 35 Circuit Information .................................................................... 15 Page 1 Addresses......................................................................... 36 Converter Operation .................................................................. 16 Registers Common to Page 0 and Page 1 ................................ 40 Internal Temperature Sensor .................................................... 17 Examples of Interfacing with the AD7284 .................................. 41 Auxiliary ADC Inputs ................................................................ 17 Register Write and Register Read Operations Examples ...... 41 Voltage References ...................................................................... 17 Conversion Data Readback Operation Examples .................. 42 Cell Connections ........................................................................ 18 Applications Information .............................................................. 44 ADC Conversions Sequence ..................................................... 19 Typical Connection Diagrams .................................................. 44 Converting with a Single AD7284 ............................................ 20 Hot Plug ....................................................................................... 47 Converting with a Chain of AD7284 Devices ......................... 21 Service Disconnect (SD) ........................................................... 47 Conversion Data Readback ....................................................... 22 Transformer Configuration ...................................................... 48 Cell Balancing Outputs .............................................................. 23 Outline Dimensions ....................................................................... 49 Open Input Detection ................................................................ 24 Ordering Guide .......................................................................... 49 Power Management ........................................................................ 25 Automotive Products ................................................................. 49 AD7284 Supplies ......................................................................... 25 REVISION HISTORY 10/2019Rev. B to Rev. C 4/2018Rev. A to Rev. B Changes to Table 5 ............................................................................ 8 Changes to Table 1 ............................................................................. 3 Changes to Figure 26 ...................................................................... 18 Changes to Figure 41 ...................................................................... 45 5/2017Revision 0: Initial Version Changes to Figure 42 ...................................................................... 46 Changes to Figure 43 and Figure 44 ............................................. 47 Rev. C Page 2 of 49