Dual-phase metering in a 20-SSOP
The AD7756ARS is an energy metering IC from the AD7756x series, configured for 2 x Single Phase measurement — it processes two independent single-phase channels from a single 20-SSOP package. Measurement error is held to ±0.4% across the full input range, which keeps the billing-grade accuracy within the ±0.5% class 1 envelope without external calibration trimming.
Housed in a 20-SSOP (0.209", 5.30 mm width) surface-mount package with a 20-SSOP supplier device package designation — the 0.0256-inch pitch demands a standard fine-pitch solder paste stencil but reflows on a standard profile without special handling.
Active lifecycle and compliance note
RoHS non-compliant — the part contains lead in the solder finish or die-attach. This is typical for legacy metering ICs still built on older wafer processes. For RoHS-required builds, the AD7751ARS (single-phase, 0.1% error) or AD7755AARSRL (single-phase, 0.1% error) are surface-mount alternatives, though they are single-channel parts and the measurement error differs.
Input impedance and signal conditioning
Input impedance is 390 kΩ — this is the effective resistance seen by the voltage-sense divider. A typical 240 V mains divider using two 1 MΩ resistors in series with the IC input presents a 2 MΩ source impedance, well below the 390 kΩ input impedance, so loading error stays under 0.1% without a buffer. Voltage thresholds for logic I/O are specified: low at 0.8 V / 0.4 V, high at 2.4 V / 4 V — the dual thresholds indicate separate digital and analog supply domains or a configurable logic interface.