The INA151 employs a transconductance-based architecture utilizing current-feedback amplifier topology to achieve low bias currents of 20μA and a common-mode voltage of 110V above negative supply. The block diagram illustrated in INA151 Simplified Example Application Schematic of INA151B demonstrates the dual-stage approach of this architecture. In the first stage the differential voltage is translated to a differential current through R1. The differential output current is further converted into a single-ended output voltage in the second amplifier stage.

The closed-loop voltage gain VOUT/VIN is established by the ratio of the internal precision resistors R3 by R1. Consequently, gain accuracy is mainly limited by the resistor matching tolerance between the signal paths, making precision thin-film resistor implementation critical for the performance.

These key architectural features make the INA151 ideally suited for serial stacked battery cell monitoring applications, enabling precise voltage measurements across up to 20 series-connected battery cells.

The INA151 encompasses four gain variants. The INA151A version offers gain option of 1, while the INA151B, INA151C and INA151D versions offer gain options of ⅔, ½ and ¼ respectively. The multiple gain variants are designed to accommodate the full-scale input ranges of various ADC requirements, maximizing measurement resolution and dynamic range.