SSP1851

The SSP1851 is a high-accuracy, fault-tolerant electrical energy measurement IC that is intended for use with 2-wire distribution systems. The part specifications surpass the accuracy requirements as quoted in the IEC1036 standard. The only analog circuitry used in the SSP1851 is in the ADCs and reference circuit. All other signal processing (e.g., multiplication and filtering) is carried out in the digital domain. This approach provides superior stability and accuracy over extremes in environmental conditions and over time. The SSP1851 incorporates a novel fault detection scheme that warns of fault conditions and allows the SSP1851 to continue accurate billing during a fault event. The SSP1851 does this by continuously monitoring both the phase and neutral (return) currents. A fault is indicated when these currents differ by more than 12.5%. Billing is continued using the larger of the two currents. The SSP1851 supplies average real power information on the low-frequency outputs F1 and F2. These logic outputs may be used to directly drive an electromechanical counter or interface to an MCU. The CF logic output gives instantaneous real power information. This output is intended to be used for calibration purposes. The SSP1851 includes a power supply monitoring circuit on the AVDD supply pin. The SSP1851 will remain in a reset condition until the supply voltage on AVDD reaches 4 V. If the supply falls below 4 V, the SSP1851 will also be reset and no pulses will be issued on F1, F2, and CF. Internal phase matching circuitry ensures that the voltage and current channels are matched whether the HPF in Channel 1 is on or off. The SSP1851 also has anticreep protection. The SSP1851 is available in 24-lead SSOP packages.