ADE7757 – Energy Metering IC with Integrated Oscillator – SOIC
The ADE7757 is a high accuracy electrical energy measurement IC. It is a pin reduction version of the ADE7755 with an enhancement of a precise oscillator circuit that serves as a clock source to the chip. The ADE7757 eliminates the cost of an external crystal or resonator, thus reducing the overall cost of a meter built with this IC. The chip directly interfaces with the shunt resistor and operates only with ac input.
The ADE7757 specifications surpass the accuracy requirements as quoted in the IEC 61036 standard. The AN-679 Application Note can be used as a basis for a description of an IEC 61036 low cost watt-hour meter reference design.
The only analog circuitry used in the ADE7757 is in the sigma-delta 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 time and extreme environmental conditions.
The ADE7757 supplies average real power information on the low frequency outputs F1 and F2. These outputs may be used to directly drive an electromechanical counter or interface with an MCU. The high frequency CF logic output, ideal for calibration purposes, provides instantaneous real power information.
The ADE7757 includes a power supply monitoring circuit on the VDD supply pin. The ADE7757 will remain inactive until the supply voltage on VDD reaches approximately 4 V. If the supply falls below 4 V, the ADE7757 will also remain inactive and the F1, F2, and CF outputs will be in their nonactive modes.
Internal phase matching circuitry ensures that the voltage and current channels are phase matched while the HPF in the current channel eliminates dc offsets. An internal no-load threshold ensures that the ADE7757 does not exhibit creep when no load is present.
The ADE7757 is available in a 16-lead SOIC narrow-body package.
- On-Chip Oscillator as Clock Source
- High Accuracy, Supposes 50 Hz/60 Hz IEC 521/IEC 61036
- Less than 0.1% Error over a Dynamic Range of 500 to 1
- The ADE7757 Supplies Average Real Power on the Frequency Outputs F1 and F2
- The High Frequency Output CF Is Intended for Calibration and Supplies Instantaneous Real Power
- The Logic Output REVP Can Be Used to Indicate a Potential Miswiring or Negative Power
- Direct Drive for Electromechanical Counters and 2-Phase Stepper Motors (F1 and F2)
- Proprietary ADCs and DSP Provide High Accuracy over Large Variations in Environmental Conditions and Time
- On-Chip Power Supply Monitoring
- On-Chip Creep Protection (No Load Threshold)
- On-Chip Reference 2.5 V (20 ppm/degC Typical) with External Overdrive Capability
- Single 5 V Supply, Low Power (20 mW Typical)
- Low Cost CMOS Process
- AC Input Only
- Max VDD to AGND: –0.3 V to +7 V
- VDD to DGND: –0.3 V to +7 V
- Analog Input Voltage to AGND V1P, V1N, V2P, and V2N: –6 V to +6 V
- Reference Input Voltage to AGND: –0.3 V to VDD + 0.3 V
- Digital Input Voltage to DGND: –0.3 V to VDD + 0.3 V
- Digital Output Voltage to DGND: –0.3 V to VDD + 0.3 V
- Storage Temperature Range: –65°C to +150°C
- Energy Meter