Active Energy Metering IC with a di/dt Sensor Interface * ADE7759 FEATURES can be switched off if the ADE7759 is used with conventional High Accuracy, Supports IEC 687/1036 current sensors. On-Chip Digital Integrator Allows Direct Interface with The ADE7759 contains a sampled waveform register and an Current Sensors with di/dt Output Such as Rogowski Coil active energy register capable of holding at least 11.53 seconds Less Than 0.1% Error over a Dynamic Range of 1000 to 1 of accumulated power at full ac load. Data is read from the On-Chip User-Programmable Threshold for Line Voltage ADE7759 via the serial interface. The ADE7759 also provides a SAG Detection and PSU Supervisory pulse output (CF) with frequency that is proportional to the Supplies Sampled Waveform Data and Active Energy active power. (40 Bits) In addition to active power information, the ADE7759 also Digital Power, Phase, and Input DC Offset Calibration provides various system calibration features, i.e., channel offset On-Chip Temperature Sensor (Typical 1 LSB/ C Resolution) correction, phase calibration, and power offset correction. The SPI Compatible Serial Interface part also incorporates a detection circuit for short duration Pulse Output with Programmable Frequency voltage drop (SAG). The voltage threshold and the duration (in Interrupt Request Pin (IRQ) and IRQ Status Register number of half-line cycles) of the drop are user programmable. Proprietary ADCs and DSP provide High Accuracy over An open-drain logic output (SAG) goes active low when a sag Large Variations in Environmental Conditions and Time event occurs. Reference 2.4 V 8% (20 ppm/ C Typical) with External Overdrive Capability A zero crossing output (ZX) produces an output that is synchro- Single 5 V Supply, Low Power Consumption (25 mW nized to the zero crossing point of the line voltage. This output Typical) can be used to extract timing or frequency information from the line. The signal is also used internally to the chip in the line GENERAL DESCRIPTION cycle energy accumulation mode i.e., the number of half-line The ADE7759 is an accurate active power and energy measure- cycles in which the energy accumulation occurs can be con- ment IC with a serial interface and a pulse output. The ADE7759 trolled. Line cycle energy accumulation enables a faster and incorporates two second-order - ADCs, a digital integrator more precise energy accumulation and is especially useful dur- (on CH1), reference circuitry, temperature sensor, and all the ing calibration. This signal is also useful for synchronization of signal processing required to perform active power and energy relay switching with a voltage zero crossing. measurement. The interrupt request output is an open drain, active low logic An on-chip digital integrator allows direct interface to di/dt output. The interrupt status register indicates the nature of the current sensors such as a Rogowski coil. The digital integrator interrupt, and the interrupt enable register controls which event eliminates the need for an external analog integrator and pro- produces an output on the IRQ pin. The ADE7759 is available vides excellent long-term stability and precise phase matching in a 20-lead SSOP package. between the current and the voltage channels. The integrator FUNCTIONAL BLOCK DIAGRAM AV DV DGND DD RESET DD ADE7759 INTEGRATOR ZX MULTIPLIER MULTIPLIER V1P dt ADC LPF2 SAG V1N HPF1 APGAIN 11:0 TEMP APOS 15:0 SENSOR PHCAL 7:0 V2P DFC ADC V2N CFNUM 11:0 CF 4k REGISTERS AND 2.4V CFDEN 11:0 REFERENCE SERIAL INTERFACE LPF1 AGND REF DIN DOUT SCLK CLKIN CLKOUT CS IRQ IN/OUT *U.S. Patents 5,745,323 5,760,617 5,862,069 5,872,469. 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 Fax: 781/326-8703 2002 Analog Devices, Inc. All rights reserved. registered trademarks are the property of their respective companies.ADE7759 TABLE OF CONTENTS FEATURES . 1 CHANNEL 1 ADC . 17 GENERAL DESCRIPTION . 1 Channel 1 ADC Gain Adjust 18 FUNCTIONAL BLOCK DIAGRAM . 1 Channel 1 Sampling . 18 SPECIFICATIONS . 3 CHANNEL 1 AND CHANNEL 2 WAVEFORM SAMPLING MODE 18 TIMING CHARACTERISTICS . 5 CHANNEL 2 ADC . 19 ABSOLUTE MAXIMUM RATINGS . 6 Channel 2 Sampling . 19 ORDERING GUIDE 6 PHASE COMPENSATION 19 PIN CONFIGURATION . 7 ACTIVE POWER CALCULATION . 20 PIN FUNCTION DESCRIPTIONS 7 ENERGY CALCULATION 21 TERMINOLOGY . 8 Integration Time under Steady Load 22 MEASUREMENT ERROR . 8 POWER OFFSET CALIBRATION 22 PHASE ERROR BETWEEN CHANNELS . 8 ENERGY-TO-FREQUENCY CONVERSION . 22 POWER SUPPLY REJECTION 8 LINE CYCLE ENERGY ACCUMULATION MODE . 24 ADC OFFSET ERROR 8 CALIBRATING THE ENERGY METER . 24 GAIN ERROR . 8 Calculating the Average Active Power . 24 GAIN ERROR MATCH 8 Calibrating the Frequency at CF . 25 TYPICAL PERFORMANCE CHARACTERISTICS (TPC) 9 Energy Meter Display . 25 TEST CIRCUITS 11 CLKIN FREQUENCY 25 ANALOG INPUTS 11 SUSPENDING THE ADE7759 FUNCTIONALITY 26 di/dt CURRENT SENSOR AND DIGITAL INTEGRATOR 12 APPLICATION INFORMATION . 26 ZERO CROSSING DETECTION . 13 SERIAL INTERFACE 26 LINE VOLTAGE SAG DETECTION 14 Serial Write Operation . 26 Sag Level Set 14 Serial Read Operation . 27 POWER SUPPLY MONITOR 14 CHECKSUM REGISTER . 28 INTERRUPTS 15 REGISTER DESCRIPTIONS 30 Using the ADE7759 Interrupts with an MCU . 15 Communications Register 30 Interrupt Timing . 15 Mode Register (06H) 31 TEMPERATURE MEASUREMENT 16 Interrupt Status Register (04H) 32 ANALOG-TO-DIGITAL CONVERSION . 16 Reset Interrupt Status Register (05H) . 32 Antialias Filter . 16 CH1OS Register (08H) 33 ADC Transfer Function 17 OUTLINE DIMENSIONS . 34 Reference Circuit . 17 REVISION HISTORY 35 2 REV. 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