Datasheet ADE7751 (Analog Devices)

a
Energy Metering IC with On-Chip Fault Detection ADE7751* FEATURES
The only analog circuitry used in the ADE7751 is in the ADCs
High Accuracy, Surpasses 50 Hz/60 Hz IEC 687/1036
and reference circuit. All other signal processing (e.g., multipli-
Less than 0.1% Error over a Dynamic Range of 500 to 1
cation and filtering) is carried out in the digital domain. This
Supplies Average Real Power on the Frequency
approach provides superior stability and accuracy over extremes
Outputs F1 and F2
in environmental conditions and over time.
High-Frequency Output CF Is Intended for Calibration
The ADE7751 incorporates a novel fault detection scheme that
and Supplies Instantaneous Real Power
warns of fault conditions and allows the ADE7751 to continue
Continuous Monitoring of the Phase and Neutral
accurate billing during a fault event. The ADE7751 does this
Current Allows Fault Detection in 2-Wire
by continuously monitoring both the phase and neutral (return)
Distribution Systems
currents. A fault is indicated when these currents differ by more
ADE7751 Uses the Larger of the Two Currents (Phase
than 12.5%. Billing is continued using the larger of the two currents.
or Neutral) to Bill—Even During a Fault Condition Two Logic Outputs (FAULT and REVP) Can Be Used to
The ADE7751 supplies average real power information on the
Indicate a Potential Miswiring or Fault Condition
low-frequency outputs F1 and F2. These logic outputs may be
Direct Drive for Electromechanical Counters and
used to directly drive an electromechanical counter or interface
2-Phase Stepper Motors (F1 and F2)
to an MCU. The CF logic output gives instantaneous real power
A PGA in the Current Channel Allows the Use of Small
information. This output is intended to be used for calibration purposes.
Values of Shunt and Burden Resistance
The ADE7751 includes a power supply monitoring circuit on the
Proprietary ADCs and DSP Provide High Accuracy over
AVDD supply pin. The ADE7751 will remain in a reset condition
Large Variations in Environmental Conditions and Time
until the supply voltage on AVDD reaches 4 V. If the supply falls
On-Chip Power Supply Monitoring
below 4 V, the ADE7751 will also be reset and no pulses will be
On-Chip Creep Protection (No Load Threshold)
issued on F1, F2, and CF.
On-Chip Reference 2.5 V
ⴞ
8% (30 ppm/
ⴗ
C Typical)
Internal phase matching circuitry ensures that the voltage and
with External Overdrive Capability
current channels are matched whether the HPF in Channel 1 is
Single 5 V Supply, Low Power (15 mW Typical)
on or off. The ADE7751 also has anticreep protection.
Low-Cost CMOS Process
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.
FUNCTIONAL BLOCK DIAGRAM G0 G1 AV AGND FAULT AC/DC DD DVDD DGND ADE7751 POWER SIGNAL SUPPLY MONITOR PROCESSING A<>B BLOCK V1A ...110101... A ADC HPF PGA A>B V1N
ⴛ
1,
ⴛ
2,
ⴛ
8,
ⴛ
16
⌽
...110101... B PHASE ADC CORRECTION MULTIPLIER V1B PGA B>A
ⴛ
1,
ⴛ
2,
ⴛ
8,
ⴛ
16 LPF V2P ...11011001... ADC V2N DIGITAL-TO-FREQUENCY CONVERTER 4k
⍀
2.5V REFERENCE REF CLKIN CLKOUT SCF S0 S1 REVP CF F1 F2 RESET IN/OUT
*US Patent 5,745,323; 5,760,617; 5,862,069; 5,872,469. REV. 0 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
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