Energy Metering IC with Integrated Oscillator * ADE7757 FEATURES built with this IC. The chip directly interfaces with the shunt On-Chip Oscillator as Clock Source resistor and operates only with ac input. High Accuracy, Supposes 50 Hz/60 Hz IEC 521/IEC 61036 The ADE7757 specifications surpass the accuracy requirements Less than 0.1% Error over a Dynamic Range of 500 to 1 as quoted in the IEC 61036 standard. The AN-679 Application The ADE7757 Supplies Average Real Power on the Note can be used as a basis for a description of an IEC 61036 Frequency Outputs F1 and F2 low cost watt-hour meter reference design. The High Frequency Output CF Is Intended for The only analog circuitry used in the ADE7757 is in the - Calibration and Supplies Instantaneous Real Power ADCs and reference circuit. All other signal processing (e.g., The Logic Output REVP Can Be Used to Indicate a multiplication and filtering) is carried out in the digital domain. Potential Miswiring or Negative Power This approach provides superior stability and accuracy over Direct Drive for Electromechanical Counters and time and extreme environmental conditions. 2-Phase Stepper Motors (F1 and F2) Proprietary ADCs and DSP Provide High Accuracy over The ADE7757 supplies average real power information on the Large Variations in Environmental Conditions and low frequency outputs F1 and F2. These outputs may be used Time to directly drive an electromechanical counter or interface with On-Chip Power Supply Monitoring an MCU. The high frequency CF logic output, ideal for calibra- On-Chip Creep Protection (No Load Threshold) tion purposes, provides instantaneous real power information. On-Chip Reference 2.5 V (20 ppm/ C Typical) The ADE7757 includes a power supply monitoring circuit on with External Overdrive Capability the V supply pin. The ADE7757 will remain inactive until DD Single 5 V Supply, Low Power (20 mW Typical) the supply voltage on V reaches approximately 4 V. If the DD Low Cost CMOS Process supply falls below 4 V, the ADE7757 will also remain inactive AC Input Only and the F1, F2, and CF outputs will be in their nonactive modes. GENERAL DESCRIPTION Internal phase matching circuitry ensures that the voltage and The ADE7757 is a high accuracy electrical energy measurement current channels are phase matched while the HPF in the cur- IC. It is a pin reduction version of the ADE7755 with an enhance- rent channel eliminates dc offsets. An internal no-load threshold ment of a precise oscillator circuit that serves as a clock source ensures that the ADE7757 does not exhibit creep when no load to the chip. The ADE7757 eliminates the cost of an external is present. crystal or resonator, thus reducing the overall cost of a meter The ADE7757 is available in a 16-lead SOIC narrow-body package. FUNCTIONAL BLOCK DIAGRAM V AGND DGND DD ADE7757 POWER SUPPLY MONITOR SIGNAL PROCESSING BLOCK V2P ...110101... - ADC MULTIPLIER V2N LPF PHASE CORRECTION HPF ...11011001... V1N - ADC V1P DIGITAL-TO-FREQUENCY INTERNAL CONVERTER OSCILLATOR 4k 2.5V REFERENCE REF RCLKIN S0 REVP CF F1 SCF S1 F2 IN/OUT *U.S. Patents REV. A Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. may result from its use. No license is granted by implication or otherwise Tel: 781/329-4700 www.analog.com under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. Fax: 781/326-8703 2003 Analog Devices, Inc. All rights reserved.(V = 5 V 5%, AGND = DGND = 0 V, On-Chip Reference, RCLKIN = 6.2 k , DD ADE7757SPECIFICATIONS 0.5% 50 ppm/ C, T to T = 40 C to +85 C, unless otherwise noted.) MIN MAX Parameter Value Unit Test Conditions/Comments 1, 2 ACCURACY 1 Measurement Error on Channel V1 Channel V2 with Full-Scale Signal (165 mV), 25C 0.1 % Reading typ Over a Dynamic Range 500 to 1 1 Phase Error between Channels Line Frequency = 45 Hz to 65 Hz V1 Phase Lead 37 (PF = 0.8 Capacitive) 0.1 Degrees () max V1 Phase Lag 60 (PF = 0.5 Inductive) 0.1 Degrees () max 1 AC Power Supply Rejection S0 = S1 = 1, Output Frequency Variation (CF) 0.2 % Reading typ V1 = 21.2 mV rms, V2 = 116.7 mV rms 50 Hz Ripple on V of 200 mV rms 100 Hz DD 1 DC Power Supply Rejection S0 = S1 = 1, Output Frequency Variation (CF) 0.3 % Reading typ V1 = 21.2 mV rms, V2 = 116.7 mV rms, V = 5 V 250 mV DD ANALOG INPUTS See Analog Inputs section Channel V1 Maximum Signal Level 30 mV max V1P and V1N to AGND Channel V2 Maximum Signal Level 165 mV max V2P and V2N to AGND Input Impedance (DC) 320 k min OSC = 450 kHz, RCLKIN = 6.2 k , 0.5% 50 ppm/C Bandwidth (3 dB) 7 kHz nominal OSC = 450 kHz, RCLKIN = 6.2 k , 0.5% 50 ppm/C 1, 2 ADC Offset Error 18 mV max See Terminology Section and Typical Performance Characteristics 1 Gain Error 4% Ideal typ External 2.5 V Reference V1 = 21.2 mV rms, V2 = 116.7 mV rms OSCILLATOR FREQUENCY (OSC) 450 kHz nominal RCLKIN = 6.2 k , 0.5% 50 ppm/C 1 Oscillator Frequency Tolerance 12 % Reading typ 1 Oscillator Frequency Stability 30 ppm/C typ REFERENCE INPUT REF Input Voltage Range 2.7 V max 2.5 V + 8% IN/OUT 2.3 V min 2.5 V 8% Input Capacitance 10 pF max ON-CHIP REFERENCE Nominal 2.5 V Reference Error 200 mV max Temperature Coefficient 20 ppm/C typ 3 LOGIC INPUTS SCF, S0, S1, Input High Voltage, V 2.4 V min V = 5 V 5% INH DD Input Low Voltage, V 0.8 V max V = 5 V 5% INL DD Input Current, I 1 A max Typically 10 nA, V = 0 V to V IN IN DD Input Capacitance, C 10 pF max IN 3 LOGIC OUTPUTS F1 and F2 Output High Voltage, V I = 10 mA OH SOURCE 4.5 V min V = 5 V DD Output Low Voltage, V I = 10 mA OL SINK 0.5 V max V = 5 V DD CF Output High Voltage, V I = 5 mA OH SOURCE 4V min V = 5 V DD Output Low Voltage, VOL I = 5 mA SINK 0.5 V max V = 5 V DD 1, 2 Frequency Output Error (CF) 10 % Ideal typ External 2.5 V Reference, V1 = 21.2 mV rms, V2 = 116.7 mV rms POWER SUPPLY For Specified Performance V 4.75 V min 5 V 5% DD 5.25 V max 5 V + 5% I 5 mA max Typically 4 mA DD NOTES 1 See Terminology section for explanation of specifications. 2 See plots in Typical Performance Characteristics. 3 Sample tested during initial release and after any redesign or process change that may affect this parameter. Specifications subject to change without notice. 2 REV. A