Energy Metering IC with Integrated Oscillator and Positive Power Accumulation ADE7768 The ADE7768 specifications surpass the accuracy require- FEATURES ments of the IEC62053-21 standard. The AN-679 Application On-chip oscillator as clock source Note can be used as a basis for a description of an IEC61036 High accuracy, supports 50 Hz/60 Hz IEC62053-21 (equivalent to IEC62053-21) low cost, watt-hour meter Less than 0.1% error over a dynamic range of 500 to 1 reference design. Supplies positive-only average real power on frequency outputs F1 and F2 The only analog circuitry used in the ADE7768 is in the - High frequency output CF calibrates and supplies ADCs and reference circuit. All other signal processing, such as instantaneous, positive-only real power multiplication and filtering, is carried out in the digital domain. Logic output REVP indicates potential miswiring or negative This approach provides superior stability and accuracy over power time and extreme environmental conditions. Direct drive for electromechanical counters and 2-phase stepper motors (F1 and F2) The ADE7768 supplies positive-only average real power Proprietary ADCs and DSPs provide high accuracy over information on the low frequency outputs, F1 and F2. These large variations in environmental conditions and time outputs can be used to directly drive an electromechanical On-chip power supply monitoring counter or interface with an MCU. The high frequency CF logic On-chip creep protection (no-load threshold) output, ideal for calibration purposes, provides instantaneous On-chip reference 2.45 V (20 ppm/C typical) with positive-only, real power information. external overdrive capability Single 5 V supply, low power (20 mW typical) The ADE7768 includes a power supply monitoring circuit on Low cost CMOS process the VDD supply pin. The ADE7768 remains inactive until the supply voltage on V reaches approximately 4 V. If the supply DD GENERAL DESCRIPTION falls below 4 V, the ADE7768 also remains inactive and the F1, 1 The ADE7768 is a high accuracy, electrical energy metering IC. F2, and CF outputs are in their nonactive modes. It is a pin reduction version of the ADE7755, enhanced with a Internal phase matching circuitry ensures that the voltage and precise oscillator circuit that serves as a clock source to the chip. current channels are phase matched, while the HPF in the The ADE7768 eliminates the cost of an external crystal or current channel eliminates dc offsets. An internal no-load resonator, thus reducing the overall cost of a meter built with threshold ensures that the ADE7768 does not exhibit creep this IC. The chip directly interfaces with the shunt resistor. when no load is present. When REVP is logic high, the ADE7768 does not generate any pulse on F1, F2, and CF. 1 U.S. Patents 5,745,323 5,760,617 5,862,069 5,872,469 others pending. The ADE7768 comes in a 16-lead, narrow body SOIC package. FUNCTIONAL BLOCK DIAGRAM V AGND DGND DD 1 6 13 ADE7768 POWER SUPPLY MONITOR SIGNAL PROCESSING BLOCK V2P 2 + ...110101... - ADC V2N 3 MULTIPLIER PHASE LPF CORRECTION 4 ...11011001... V1N - ADC HPF V1P 5 + DIGITAL-TO-FREQUENCY INTERNAL OSCILLATOR CONVERTER 4k 2.5V REFERENCE 7 11 8 10 9 12 14 16 15 REF RCLKIN REVP CF F1 SCF S0 S1 F2 IN/OUT Figure 1. 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 may result from its use. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Specifications subject to change without notice. No license is granted by implication Tel: 781.329.4700 www.analog.com or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. Fax: 781.461.3113 2005 Analog Devices, Inc. All rights reserved. 05331-001ADE7768 TABLE OF CONTENTS Specifications..................................................................................... 3 Power Supply Monitor............................................................... 12 Timing Characteristics ................................................................ 4 Internal Oscillator (OSC).......................................................... 14 Absolute Maximum Ratings............................................................ 5 Transfer Function....................................................................... 14 ESD Caution.................................................................................. 5 Selecting a Frequency for an Energy Meter Application ...... 15 Terminology ...................................................................................... 6 No-Load Threshold.................................................................... 16 Pin Configuration and Function Descriptions............................. 7 Negative Power Information..................................................... 16 Typical Performance Characteristics ............................................. 8 Evaluation Board and Reference Design Board..................... 16 Functional Description .................................................................. 10 Outline Dimensions....................................................................... 17 Theory of Operation .................................................................. 10 Ordering Guide .......................................................................... 17 Analog Inputs.............................................................................. 11 Revision History 8/05Sp0 to Rev. A Rev. A Page 2 of 20