0.1% measurement error — what that means on the bench
The AD71056ARZ is a single-phase energy metering IC that reports active energy with a maximum measurement error of 0.1% across the dynamic range. For a calibration technician, that 0.1% is the total unadjusted error budget — the combined effect of offset, gain, and nonlinearity in the analog front end. If your reference standard is a 0.01% class source, the AD71056ARZ contributes an order of magnitude more uncertainty than the reference, so the final system error is dominated by the metering IC, not the reference. The 320 kOhm input impedance means the IC loads the voltage-sense resistor divider by less than 15 µA at 240 VAC nominal — negligible for a divider in the 1 MOhm range. The current channel impedance is not separately specified, but the 5 mA supply current suggests the analog front end is biased for low-power operation, consistent with a meter that runs continuously.
Supply rails and temperature grade
If your board has a 5 V rail that droops below 4.75 V under load, the IC may drop out of specification. The 5 mA typical supply current is low enough that a 78L05 regulator can power it without a heatsink, but the regulator's dropout voltage must leave headroom above 4.75 V at the IC pin. The 0.1% measurement error is specified at 25°C typical; the datasheet's temperature coefficient of the error (not in this summary) would determine how much the error drifts at the extremes. For a meter that sees -20°C in an outdoor enclosure, the 0.1% figure is a room-temperature baseline, not a guaranteed limit across the full range.
Package, footprint, and the tape-and-reel sibling
The AD71056ARZ ships in a tube — 16-SOIC wide-body (0.154-inch width, 3.90 mm). The tube orientation is standard JEDEC; the ICs are oriented pin-1 left in the tube. The tape-and-reel sibling AD71056ARZ-RL is electrically identical — same die, same 0.1% error, same 320 kOhm input impedance. The only difference is the packaging format: tube vs tape-and-reel. If your pick-and-place line is set up for tape, order the -RL variant; if you have a tube feeder or hand-place, the -ARZ works. No rewiring or board change is needed between the two — they drop into the same footprint.