Datasheet ADE7755 (Analog Devices) - 7

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Data Sheet ADE7755 Pin No. Mnemonic Description
17 CLKIN An external clock can be provided at this logic input. Alternatively, a parallel resonant AT crystal can be connected across CLKIN and CLKOUT to provide a clock source for the ADE7755. The clock frequency for specified operation is 3.579545 MHz. Crystal load capacitance of between 22 pF and 33 pF (ceramic) should be used with the gate oscillator circuit. 18 CLKOUT A crystal can be connected across this pin and CLKIN to provide a clock source for the ADE7755. The CLKOUT pin can drive one CMOS load when an external clock is supplied at CLKIN or by the gate oscillator circuit. 20 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 detected again. The output goes high or low at the same time that a pulse is issued on CF. 21 DGND This pin provides the ground reference for digital circuitry in the ADE7755, that is, the multiplier, filters, and digital-to-frequency converter. 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, for example, counters (mechanical and digital), MCUs, and indicator LEDs. For good noise suppression, the analog ground plane should be connected to the digital ground plane at one point only, for example, a star ground. 22 CF Calibration Frequency Logic Output. The CF logic output gives instantaneous active power information. This output is intended to be used for calibration purposes. Also, see the SCF pin description. 23, 24 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. See the Transfer Function section. Rev. B | Page 7 of 20 Document Outline Features General Description Functional Block Diagram Revision History Specifications Timing Characteristics Absolute Maximum Ratings ESD Caution Pin Configuration and Function Descriptions Typical Performance Characteristics Terminology Theory of Operation Power Factor Considerations Nonsinusoidal Voltage and Current Analog Inputs Channel 1 (Current Channel) Channel 2 (Voltage Channel) Typical Connection Diagrams Power Supply Monitor HPF and Offset Effects Digital-to-Frequency Conversion Interfacing the ADE7755 to a Microcontroller for Energy Measurement Power Measurement Considerations Transfer Function Frequency Outputs F1 and F2 Example 1 Example 2 Frequency Output CF Selecting a Frequency for an Energy Meter Application Frequency Outputs No Load Threshold Outline Dimensions Ordering Guide