Datasheet ADE7761B (Analog Devices) - 7

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ADE7761B Pin No. Mnemonic Description
15 FAULT This logic output goes active high when a fault or missing neutral condition occurs. A fault is defined as a condition under which the signals on V1A and V1B differ by more than 6.25%. A missing neutral condition is defined when the chip is powered up with no voltage at the input. The logic output is reset to 0 when a fault or missing neutral condition is no longer detected. See the Fault Detection section and the Missing Neutral Mode section. 16 REVP This logic output goes logic high when negative power is detected, that is, when the phase angle between the voltage and current signals is greater than 90°. This output is not latched and is reset when positive power is once again detected. The output goes high or low at the same time that a pulse is issued on CF. 17 DGND Digital Ground. This pin provides the ground reference for the digital circuitry in the ADE7761B, that is, multiplier, filters, and digital-to-frequency converters. This pin should be tied to the digital ground plane of the PCB. The digital ground plane is the ground reference for all digital circuitry, such as counters (mechanical and digital), MCUs, and indicator LEDs. For good noise suppression, the analog ground plane should be connected to the digital ground plane only at the DGND pin. 18 CF Calibration Frequency Logic Output. The CF logic output, active high, gives instantaneous active power information. This output is used for operational and calibration purposes. See the Digital-to-Frequency Conversion section. 19, 20 F2, F1 Low Frequency Logic Outputs. F1 and F2 supply average active power information. The logic outputs can be used to directly drive electromechanical counters and 2-phase stepper motors. Rev. 0 | Page 7 of 24 Document Outline FEATURES GENERAL DESCRIPTION FUNCTIONAL BLOCK DIAGRAM TABLE OF CONTENTS REVISION HISTORY SPECIFICATIONS TIMING CHARACTERISTICS Timing Diagram ABSOLUTE MAXIMUM RATINGS PERFORMANCE ISSUES THAT MAY AFFECT BILLING ACCURACY Case 1 Case 2 ESD CAUTION PIN CONFIGURATION AND FUNCTION DESCRIPTIONS TYPICAL PERFORMANCE CHARACTERISTICS TEST CIRCUIT TERMINOLOGY THEORY OF OPERATION POWER SUPPLY MONITOR ANALOG INPUTS Channel V1 (Current Channel) Channel V2 (Voltage Channel) MISCAL Input Typical Connection Diagrams INTERNAL OSCILLATOR ANALOG-TO-DIGITAL CONVERSION Antialias Filter ACTIVE POWER CALCULATION Power Factor Considerations Nonsinusoidal Voltage and Current HPF and Offset Effects DIGITAL-TO-FREQUENCY CONVERSION TRANSFER FUNCTION Frequency Output F1 and Frequency Output F2 Frequency Output CF FAULT DETECTION Fault with Active Input Greater Than Inactive Input Fault with Inactive Input Greater Than Active Input Calibration Concerns MISSING NEUTRAL MODE Important Note for Billing of Active Energy Missing Neutral Detection Missing Neutral Gain Calibration APPLICATIONS INFORMATION INTERFACING TO A MICROCONTROLLER FOR ENERGY MEASUREMENT SELECTING A FREQUENCY FOR AN ENERGY METER APPLICATION Frequency Outputs No-Load Threshold NEGATIVE POWER INFORMATION OUTLINE DIMENSIONS ORDERING GUIDE