AD8451

Low Cost, Precision Analog Front End and Controller for Battery Test/Formation Systems Data Sheet 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 AD8451 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...