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use, nor for any infringements of patents or other rights of third parties that
may result from its use. No license is granted by implication or otherwise
under any patent or patent rights of Analog Devices.
a
ADE7751
*
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700www.analog.com
Fax: 781/326-8703 © Analog Devices, Inc., 2002
Energy Metering IC
with On-Chip Fault Detection
FEATURES
High Accuracy, Surpasses 50 Hz/60 Hz IEC 687/1036
Less than 0.1% Error over a Dynamic Range of 500 to 1
Supplies Average Real Power on the Frequency
Outputs F1 and F2
High-Frequency Output CF Is Intended for Calibration
and Supplies Instantaneous Real Power
Continuous Monitoring of the Phase and Neutral
Current Allows Fault Detection in 2-Wire
Distribution Systems
ADE7751 Uses the Larger of the Two Currents (Phase
or Neutral) to Bill—Even During a Fault Condition
Two Logic Outputs (FAULT and REVP) Can Be Used to
Indicate a Potential Miswiring or Fault Condition
Direct Drive for Electromechanical Counters and
2-Phase Stepper Motors (F1 and F2)
A PGA in the Current Channel Allows the Use of Small
Values of Shunt and Burden Resistance
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 ⴞ 8% (30 ppm/ⴗC Typical)
with External Overdrive Capability
Single 5 V Supply, Low Power (15 mW Typical)
Low-Cost CMOS Process
FUNCTIONAL BLOCK DIAGRAM
AC/DC
AV
DD
DV
DD
HPF
AGND
DGND
PHASE
CORRECTION
4k⍀
...
110101
...
SIGNAL
PROCESSING
BLOCK
PGA
ⴛ1, ⴛ2, ⴛ8, ⴛ16
POWER
SUPPLY MONITOR
ADE7751
...
11011001
...
2.5V
REFERENCE
PGA
ⴛ1, ⴛ2, ⴛ8, ⴛ16
ADC
...
110101
...
B>A
A>B
A<>B
ADC
ADC
⌽
FAULT
MULTIPLIER
LPF
DIGITAL-TO-FREQUENCY
CONVERTER
G0 G1
V1A
V1N
V2P
V2N
V1B
A
B
CLKOUTCLKINREF
IN/OUT
RESET
F1
F2CFREVPSCF S0 S1
*US Patent 5,745,323; 5,760,617; 5,862,069; 5,872,469.
The only analog circuitry used in the ADE7751 is in the ADCs
and reference circuit. All other signal processing (e.g., multipli-
cation and filtering) is carried out in the digital domain. This
approach provides superior stability and accuracy over extremes
in environmental conditions and over time.
The ADE7751 incorporates a novel fault detection scheme that
warns of fault conditions and allows the ADE7751 to continue
accurate billing during a fault event. The ADE7751 does this
by continuously monitoring both the phase and neutral (return)
currents. A fault is indicated when these currents differ by more
than 12.5%. Billing is continued using the larger of the two currents.
The ADE7751 supplies average real power information on the
low-frequency outputs F1 and F2. These logic outputs may be
used to directly drive an electromechanical counter or interface
to an MCU. The CF logic output gives instantaneous real power
information. This output is intended to be used for calibration purposes.
The ADE7751 includes a power supply monitoring circuit on the
AV
DD
supply pin. The ADE7751 will remain in a reset condition
until the supply voltage on AV
DD
reaches 4 V. If the supply falls
below 4 V, the ADE7751 will also be reset and no pulses will be
issued on F1, F2, and CF.
Internal phase matching circuitry ensures that the voltage and
current channels are matched whether the HPF in Channel 1 is
on or off. The ADE7751 also has anticreep protection.
The ADE7751 is available in 24-lead DIP and SSOP packages.
GENERAL DESCRIPTION
The ADE7751 is a high-accuracy, fault-tolerant electrical energy
measurement IC that is intended for use with 2-wire distribution
systems. The part specifications surpass the accuracy require-
ments as quoted in the IEC1036 standard.
