Low Cost, Precision Analog Front End and
Controller for Battery Test/Formation Systems
Data Sheet
AD8451
FEATURES
GENERAL DESCRIPTION
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
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.
Low current sense amplifier input voltage noise: 9 nV/√Hz typ
Current sense CMRR: 108 dB min
TTL compliant logic
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.
APPLICATIONS
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.
Battery cell formation and testing
Battery module testing
FUNCTIONAL BLOCK DIAGRAM
ISREFH/
ISREFL ISMEA ISET IVE0/IVE1
VINT
AD8451
ISVP
CONSTANT
VCLP
CURRENT LOOP
MUX
FILTER
26
×1
VCTRL
VCLN
ISVN
MODE
BVP
CURRENT
SENSE IA
(CHARGE/
DISCHARGE)
SWITCHING
VOLTAGE
SENSE DA
VOLTAGE
REFERENCE
VREF
0.8
CONSTANT
VOLTAGE LOOP
FILTER
BVN
BVREFH/
BVREFL
BVMEA VSET VVE0/
VVE1
VVP0
VSETBF VINT
Figure 1.
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
rightsof third parties that may result fromits 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 andregisteredtrademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
Technical Support
©2014 Analog Devices, Inc. All rights reserved.
www.analog.com