80-V bidirectional current sense with zero-drift topology
The INA254A1IPWAR is a single-channel current-sense amplifier from Texas Instruments' Zero-Drift series, designed to measure bidirectional current across a shunt resistor at common-mode voltages up to 80 V. The zero-drift architecture keeps offset drift low over temperature, which matters when the sensed current is small relative to the shunt's full-scale range.
The 350 kHz -3 dB bandwidth and 2.4 V/µs slew rate set the upper limit for tracking fast current transients; a motor-drive phase current sampled at 20 kHz is well within the passband, but a switching-node transient at 500 kHz will be attenuated. Input bias current is 90 µA — high compared to a general-purpose op-amp, but this is typical for a shunt-based current sense where the bias current flows through the shunt and adds a small offset error. The zero-drift loop cancels the offset, so the net error at the output is dominated by the shunt tolerance and the amplifier's gain accuracy, not the bias current.
The Zero-Drift series is an established family, so long-term supply risk is low.