AD8451 Datasheet, PDF (1/32 Pages) Analog Devices – Low Cost, Precision Analog Front End and Controller for Battery Test/Formation Systems

Data Sheet
Low Cost, Precision Analog Front End and
Controller for Battery Test/Formation Systems
AD8451
FEATURES
Integrated constant current and voltage modes with
automatic switchover
Charge and discharge modes
Precision voltage and current measurement
Integrated precision control feedback blocks
Precision interface to PWM or linear power converters
Fixed gain settings
Current sense gain: 26 V/V (typ)
Voltage sense gain: 0.8 V/V (typ)
Excellent ac and dc performance
Maximum offset voltage drift: 0.9 µV/°C
Maximum gain drift: 3 ppm/°C
Low current sense amplifier input voltage noise: 9 nV/√Hz typ
Current sense CMRR: 108 dB min
TTL compliant logic
APPLICATIONS
Battery cell formation and testing
Battery module testing
GENERAL DESCRIPTION
The AD8451 is a precision analog front end and controller for
testing and monitoring battery cells. A precision fixed gain
instrumentation amplifier (IA) measures the battery charge/
discharge current, and a fixed gain difference amplifier (DA)
measures the battery voltage (see Figure 1). Internal laser
trimmed resistor networks set the gains for the IA and the DA,
optimizing the performance of the AD8451 over the rated
temperature range. The IA gain is 26 V/V and the DA gain is
0.8 V/V.
Voltages at the ISET and VSET inputs set the desired constant
current (CC) and constant voltage (CV) values. CC to CV
switching is automatic and transparent to the system.
A TTL logic level input, MODE, selects the charge or discharge
mode (high for charge, and low for discharge). An analog output,
VCTRL, interfaces directly with the Analog Devices, Inc.,
ADP1972 pulse-width modulation (PWM) controller.
The AD8451 simplifies designs by providing excellent accuracy,
performance over temperature, flexibility with functionality,
and overall reliability in a space-saving package. The AD8451 is
available in an 80-lead, 14 mm × 14 mm × 1.40 mm LQFP and
is rated for an operating temperature of −40°C to +85°C.
ISVP
ISVN
MODE
BVP
BVN
FUNCTIONAL BLOCK DIAGRAM
ISREFH/
ISREFL ISMEA ISET IVE0/IVE1
VINT
MUX
26
CURRENT
SENSE IA
VOLTAGE
SENSE DA
0.8
CONSTANT
CURRENT LOOP
FILTER
(CHARGE/
DISCHARGE)
SWITCHING
CONSTANT
VOLTAGE LOOP
FILTER
AD8451
VCLP
×1
VCTRL
VCLN
VOLTAGE
REFERENCE
VREF
BVREFH/
BVREFL
BVMEA VSET VVE0/ VVP0
VVE1
Figure 1.
VSETBF VINT
Rev. 0
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
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarks and registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone]
©2014 Analog Devices, Inc. All rights reserved.
Technical Support
www.analog.com