Low Cost, Precision Analog Front End and

Controller for Battery Test/Formation Systems

Data Sheet

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.

FUNCTIONAL BLOCK DIAGRAM

CURRENT

SENSE IA

VOLTAGE

SENSE DA

ISMEA

ISET

BVMEA

VSET

VINT

MUX

ISVN

ISVP

BVN

BVP

VINT

VCTRL

×1

MODE

AD8451

IVE0/IVE1

VVE0/

VVE1

(CHARGE/

DISCHARGE)

SWITCHING

VVP0

VSETBF

VCLP

VCLN

BVREFH/

BVREFL

ISREFH/

ISREFL

VREF

0.8

VOLTAGE

REFERENCE

CONSTANT

VOLTAGE LOOP

FILTER

CONSTANT

CURRENT LOOP

FILTER

26

Figure 1.

Rev. 0

Document Feedback

Information furnished by Analog Devices is believed to be accurate and reliable. However, no

responsibilityisassumedbyAnalogDevicesforitsuse,norforanyinfringementsofpatentsorother

rightsofthirdpartiesthatmayresultfromitsuse.Specificationssubjecttochangewithoutnotice.No

license is granted by implication or otherwise under any patent or patent rights of Analog Devices.

Trademarksandregisteredtrademarksarethepropertyoftheirrespectiveowners.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: 781.329.4700

©2014 Analog Devices, Inc. All rights reserved.

Technical Support

www.analog.com