Analog Devices: CN0235 Reference Design for Fully Isolated Lithium Ion Battery Monitoring and Protection System

atomar — Sun, 27 Oct 2013 06:01:54 GMT

Current Revision posted to Documents by atomar on 10/27/2013 6:01:54 AM

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Kit Overview

Lithium ion (Li-Ion) battery stacks contain a large number of individual cells that must be monitored correctly in order to enhance the battery efficiency, prolong the battery life, and ensure safety. The 6-channel AD7280A devices in the EVAL-CN0235-SDPZEVAL-CN0235-SDPZ circuit act as the primary monitor providing accurate voltage measurement data to the System Demonstration Platform (SDP-B EVAL-SDP-CB1ZEVAL-SDP-CB1Z) evaluation board, and the 6-channel AD8280AD8280 devices act as the secondary monitor and protection system. Both devices can operate from a single wide supply range of 8V to 30V and operate over the industrial temperature range of −40°C to +105°C.

The AD7280AAD7280A contains an internal ±3 ppm reference that allows a cell voltage measurement accuracy of ±1.6 mV. The ADC resolution is 12 bits and allows conversion of up to 48 cells within 7 μs. The AD7280A has cell balancing interface outputs designed to control external FET transistors to allow discharging of individual cells and forcing all the cells in the stack to have identical voltages.

The AD7280AAD7280A and AD8280AD8280, which reside on the high voltage side of the battery management system (BMS) have a daisychain interface, which allows up to eight AD7280A’s and eight AD8280’s to be stacked together and allows for 48 Li-Ion cell voltages to be monitored. Adjacent AD7280A's and AD8280’s in the stack can communicate directly, passing data up and down the stack without the need for isolation.

The master devices on the bottom of the stack use the SPI interface and GPIOs to communicate with the SDP-B evaluation board, and it is only at this point that high voltage galvanic isolation is required to protect the low voltage side of the SDP-B board. The ADuM1400ADuM1400, ADuM1401ADuM1401 digital isolator, and the ADuM5404 isolator with integrated dc-to-dc converter combine to provide the required eleven channels of isolation in a compact and cost effective solution. The ADuM5404 also provides isolated 5 V to the VDRIVE input of the lower AD7280A and the VDD2 supply voltage for the ADuM1400 and ADUM1401ARWZ.ADUM1401ARWZ. isolators.

This circuit uses the EVAL-CN0235-SDPZEVAL-CN0235-SDPZ circuit board and the EVAL-SDP-CB1ZEVAL-SDP-CB1Z System Demonstration Platform (SDP-B) evaluation board. The two boards have 120-pin mating connectors, allowing for the quick setup and evaluation of the circuit’s performance. The EVAL-CN0235-SDPZ board contains the circuit to be evaluated and the SDP-B evaluation board is used with the CN0235 evaluation software to capture the data from the EVAL-CN0235-SDPZ circuit board.

Key Applications: Battery Management, Metering & Energy Monitoring, Power Supplies

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Development Tools

PC with a USB port and Windows® XP or Windows Vista® (32-bit), or Windows® 7 (32-bit)
EVAL-CN0235-SDPZEVAL-CN0235-SDPZ circuit evaluation board
EVAL-SDP-CB1ZEVAL-SDP-CB1Z SDP-B evaluation board
- Blackfin Processor ADSP-BF527
- USB 2.0 Interface to PC
- JTAG header footprint
- 32MB SDRAM
- 2 x Small Footprint 120 Pin Connectors
- Configurable Peripheral Interfaces - SPI - SPORT - I2C - GPIOs - Parallel - Timers
CN0235 SDP evaluation software
Power supply: +6 V (EVAL-CFTL-6V-PWRZEVAL-CFTL-6V-PWRZ) or +6 V “wall wart”
Li-Ion batteries or precision dc supply

Technical Documents

Learning Center

Type	Description
User Manual	ADI: User Manual (CN-0235) for Fully Isolated Lithium Ion Battery Monitoring and Protection System
User Guide	ADI: User Guide for EVAL-SDP-CB1Z
Datasheet	ADI: Datasheet for AD7280A: Lithium Ion Battery Monitoring System (Rev 0)
Datasheet	ADI: Datasheet for AD8280: Lithium Ion Battery Safety Monitor (Rev C)
Datasheet	ADI: Datasheet for ADuM1400/ADuM1401/ADuM1402: Quad-Channel Digital Isolators (Rev H)
Datasheet	ADI: Datasheet for ADuM5401/ADuM5402/ADuM5403/ADuM5404: Quad-Channel Isolators with Integrated DC-to-DC Converter (Rev C)
Application Note	ADI: Application Note (AN-0971) for Recommendations for Control of Radiated Emissions with isoPower Devices

Design Elements

Type	Description
Schematics	ADI: Schematics for EVAL-CN0235-SDPZ Evaluation Board
Layout	ADI: Layout for EVAL-CN0235-SDPZ
BOM	ADI: Bill Of Material (BOM) for EVAL-CN0235-SDPZ Evaluation Board

Video

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Kit Features

Devices Used for the EVAL-CN0235-SDPZ Evaluation Board
Key Features for ADuM1400ADuM1400: Qualified for automotive applications Low power operation 5 V operation 1.0 mA per channel maximum @ 0 Mbps to 2 Mbps 3.5 mA per channel maximum @ 10 Mbps 31 mA per channel maximum @ 90 Mbps 3 V operation 0.7 mA per channel maximum @ 0 Mbps to 2 Mbps 2.1 mA per channel maximum @ 10 Mbps 20 mA per channel maximum @ 90 Mbps Bidirectional communication 3 V/5 V level translation High temperature operation: 125°C High data rate: dc to 90 Mbps (NRZ) Precise timing characteristics 2 ns maximum pulse width distortion 2 ns maximum channel-to-channel matching High common-mode transient immunity: >25 kV/μs Output enable function	Key Features for AD7280AAD7280A: 12-bit ADC, 1 μs per channel conversion time 6 analog input channels, common-mode range 0.5 V to 27.5 V 6 auxiliary ADC inputs ±1.6 mV cell voltage accuracy On-chip voltage regulator Cell balancing interface Daisy-chain interface Internal reference: ±3 ppm/oC 1.8 μA power-down current High input impedance Serial interface with alert function 1 SPI interface for up to 48 channels CRC protection on read and write commands On-chip registers for channel sequencing VDD operating range: 8 V to 30 V

Key features for AD8280AD8280: Wide supply voltage range: 6.0 V to 30.0 V Multiple inputs can monitor 3 to 6 cell voltages and 2 temperatures Adjustable threshold levels: overvoltage, undervoltage, overtemperature Alarm options: separate or shared alarms Extended temperature range performance −40°C ≤ TA ≤ +105°C Can be daisy-chained Internal reference Powered from battery stack LDO available to power isolator Qualified for automotive applications Extensive self-test feature aids in meeting ASIL/SIL requirements	Key Features for ADuM5404: isoPower integrated, isolated dc-to-dc converter Regulated 3.3 V or 5.0 V output Up to 500 mW output power Quad dc-to-25 Mbps (NRZ) signal isolation channels 16-lead SOIC package with 7.6 mm creepage High temperature operation: 105°C maximum High common-mode transient immunity: >25 kV/μs

Devices Used for the EVAL-CN0235-SDPZ Evaluation Board

Key Features for ADuM1400ADuM1400:

Qualified for automotive applications
Low power operation
5 V operation
- 1.0 mA per channel maximum @ 0 Mbps to 2 Mbps
- 3.5 mA per channel maximum @ 10 Mbps
- 31 mA per channel maximum @ 90 Mbps
3 V operation
- 0.7 mA per channel maximum @ 0 Mbps to 2 Mbps
- 2.1 mA per channel maximum @ 10 Mbps
- 20 mA per channel maximum @ 90 Mbps
Bidirectional communication
3 V/5 V level translation
High temperature operation: 125°C
High data rate: dc to 90 Mbps (NRZ)
Precise timing characteristics
- 2 ns maximum pulse width distortion
- 2 ns maximum channel-to-channel matching
High common-mode transient immunity: >25 kV/μs
Output enable function

Key Features for AD7280AAD7280A:

12-bit ADC, 1 μs per channel conversion time
6 analog input channels, common-mode range 0.5 V to 27.5 V
6 auxiliary ADC inputs
±1.6 mV cell voltage accuracy
On-chip voltage regulator
Cell balancing interface
Daisy-chain interface
Internal reference: ±3 ppm/oC
1.8 μA power-down current
High input impedance
Serial interface with alert function
1 SPI interface for up to 48 channels
CRC protection on read and write commands
On-chip registers for channel sequencing
VDD operating range: 8 V to 30 V

Key features for AD8280AD8280:

Wide supply voltage range: 6.0 V to 30.0 V
Multiple inputs can monitor 3 to 6 cell voltages and 2 temperatures
Adjustable threshold levels: overvoltage, undervoltage, overtemperature
Alarm options: separate or shared alarms
Extended temperature range performance
−40°C ≤ TA ≤ +105°C
Can be daisy-chained
Internal reference
Powered from battery stack
LDO available to power isolator
Qualified for automotive applications
Extensive self-test feature aids in meeting ASIL/SIL requirements

Key Features for ADuM5404:

isoPower integrated, isolated dc-to-dc converter
Regulated 3.3 V or 5.0 V output
Up to 500 mW output power
Quad dc-to-25 Mbps (NRZ) signal isolation channels
16-lead SOIC package with 7.6 mm creepage
High temperature operation: 105°C maximum
High common-mode transient immunity: >25 kV/μs

Kit Contents

The Analog Devices EVAL-CN0235-SDPZEVAL-CN0235-SDPZ kit is supplied with below contents:

Evaluation Board

Tags: adum5404, ad8280, eval-cn0235-sdpz, adum1400, analog_devices, ad7280a