Description

The AD8450 is a precision analog front end for testing andmonitoring battery cells. Referring to figure one, a precisionprogrammable gain instrumentation amplifier (PGIA)measures the battery’s charge/discharge current and aprogrammable gain difference amplifier (PGDA) measures thebattery’s voltage. Internal laser trimmed resistor networks setthe gains for the PGIA and the PGDA, optimizing the AD8450’sperformance over the rated temperature range. PGIA gains are26×, 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 constantvoltage (CV) and constant current (CC) values. CC to CVswitching is automatic and transparent to the system.A TTL level logic input, MODE, selects between charge anddischarge modes (high for charge, low for discharge). An analogoutput, VCTRL, interfaces directly with ADI’s ADP1972 &ADP1974 PWM controllers.The AD8450 includes resistor programmable overvoltage andovercurrent detection and current sharing circuitry. Currentsharing is used to balance charge among multiple batteries.The AD8450 simplifies designs by providing excellent accuracy,performance over temperature, flexibility with functionality,and overall reliability in a space-saving package. The AD8450 isavailable in an 80 lead 14 mm ×14 mm × 1 mm LQFP packageand is rated at −40 °C to +85 °C operating temperature.APPLICATIONS Battery cell testing & formation Battery module testing