AD8450 Datasheet, PDF (1/41 Pages) Analog Devices – Precision Analog Front End and Controller for Battery Test/Formation Systems

Data Sheet
Precision Analog Front End and Controller
for Battery Test/Formation Systems
AD8450
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
Programmable gain settings
Current sense gains: 26, 66, 133, and 200
Voltage sense gains: 0.2, 0.27, 0.4, and 0.8
Programmable OVP and OCP fault detection
Current sharing and balancing
Excellent ac and dc performance
Maximum offset voltage drift: 0.6 µV/°C
Maximum gain drift: 3 ppm/°C
Low current sense amplifier input voltage noise: ≤9 nV/√Hz
Current sense CMRR: 126 dB minimum (gain = 200)
TTL compliant logic
The AD8450 is a precision analog front end and controller for
testing and monitoring battery cells. A precision programmable
gain instrumentation amplifier (PGIA) measures the battery
charge/discharge current, and a programmable gain difference
amplifier (PGDA) measures the battery voltage (see Figure 1).
Internal laser trimmed resistor networks set the gains for the
PGIA and the PGDA, optimizing the performance of the
AD8450 over the rated temperature range. PGIA gains are 26,
66, 133, and 200. PGDA gains are 0.2, 0.27, 0.4, and 0.8.
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, low for discharge). An analog output,
VCTRL, interfaces directly with the Analog Devices, Inc.,
ADP1972 PWM controller.
APPLICATIONS
Battery cell formation and testing
Battery module testing
The AD8450 includes resistor programmable overvoltage and
overcurrent detection and current sharing circuitry. Current
sharing is used to balance the output current of multiple
bridged channels.
The AD8450 simplifies designs by providing excellent accuracy,
performance over temperature, flexibility with functionality,
and overall reliability in a space-saving package. The AD8450 is
available in an 80-lead, 14 mm × 14 mm × 1 mm LQFP package
and is rated for an operating temperature of −40°C to +85°C.
FUNCTIONAL BLOCK DIAGRAM
ISREFH/
IVE0/
ISREFL ISMEA ISET IVE1
VINT
ISVP
ISVN
MODE
BVPx
BVNx
GAIN
NETWORK
AND MUX
26, 66,
133, 200
CURRENT
SENSE PGIA
GAIN
NETWORK
VOLTAGE
SENSE PGDA
0.2, 0.27,
0.4, 0.8
CONSTANT
CURRENT LOOP
FILTER
(CHARGE/
DISCHARGE)
SWITCHING
CONSTANT
VOLTAGE LOOP
FILTER
AD8450
CURRENT
SHARING
1×
VOLTAGE
REFERENCE
CSH
IMAX
VCLP
VCTRL
VCLN
VREF
FAULT
DETECTION
FAULT
BVREFH/ BVMEA VSET VVE0/
BVREFL
VVE1
Figure 1.
VVP0 VSETBF VINT OVPS/ OCPS/
OVPR OCPR
Rev. B
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