Product category:
Analogue and Mixed Signal ICs
News Release from: Maxim Integrated Products | Subject: MAXQ3180
Edited by the Electronicstalk Editorial
Team on 15 April 2008
Meter on a chip provides microvolt
resolution
Electricity metering chip combines an eight-channel A/D convertor and high-performance MPU for computing a broad set of polyphase multifunction energy metering parameters.
Available now from Maxim Integrated Products, the MAXQ3180 is a high-accuracy low-power polyphase IC for measuring electricity activity The device incorporates an eight-channel A/D convertor and a dedicated, high-performance MAXQ microprocessor for computing a broad set of polyphase multifunction energy metering parameters
This article was originally published on Electronicstalk on 27 Aug 2002 at 8.00am (UK)
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Six of the input channels are dedicated to the three-phase voltages and three currents.
One channel is dedicated for the neutral line current monitoring, and the eighth channel is for on-chip temperature monitoring.
With this high level integration, the MAXQ3180 makes it easy to monitor the power grid and load status.
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The MAXQ3180 monitors neutral line current flow, detects a voltage sequence error, and measures current in the absence of the phase voltages.
The device exceeds all relevant international standards for electricity metering (IEC62053-21, IEC62053-22, IEC62053-23).
To provide flexible operation, the device provides two configurable pulse outputs (typically for active and reactive energy) that can be set to output any of a large array of operational parameters.
The MAXQ3180 interfaces with a host microcontroller through the standard SPI protocol.
The industry requirements for electricity metering are evolving rapidly and becoming more challenging for both the meter design companies and the providers of electricity metering equipment.
The electric utility and the energy consumer want accurate metering, and often across a very wide dynamic range.
With huge amounts of power measured constantly, each kilowatt-hour monitored inaccurately represents significant money to power companies and/or consumers.
Some numbers illustrate the challenges that electricity metering poses for the utilities and device designers.
Four specifications are worth noting.
First, a typical class 1 meter may specify a measurement range of 1000:1 (ie the power flow must be measured accurately with the current input changing over a 1000 to 1 range).
Secondly, the maximum error specification for the metrological device is typically 0.1% of the parameter being measured over the specified dynamic range.
Thirdly, assuming the ADC full scale is 1V, the smallest signal that must be measured would be 1mV.
Therefore, with a target error of 0.1% of 1mV, the smallest signal to measure is 1uV.
To resolve 1uV out of 1V requires the use of a 20bit ADC.
So why have the above measurement specifications been so difficult to achieve with traditional electricity metering devices?.
What do these specifications and performance expectations mean for the designer of electricity metering devices? The answer starts with the ADC.
ADCs with 20bit or better accuracies do exist, but they are not cost-competitive for the mass market of energy meters.
Consequently, the provider of electricity metering devices must deliver a more economical, cost-competitive solution that contains not only adequate ADCs but also the best signal-processing chain so that the target energy error is achieved.
The MAXQ3180 integrates an eight-channel ADC and dynamic gain control that resolves the 1uV from 1V demanded by the industry.
Fourthly, the metering environment is often noisy and subject to high-voltage spikes.
The minimum EFT (electric fast transient) specification for the meter is 4kV.
This latter performance specification is equally challenging for electricity meter designers.
Circuit boards must withstand the abuse of the deployment environment and yet maintain adequate fidelity to the very small analogue input signals.
Compounding the need for high accuracy at the lowest possible cost is the dynamic nature of the electricity market itself.
New monitoring metrics frequently emerge, and are then requested by the utility companies.
Recent examples include power theft detection, real-time power quality monitoring and consumption pattern reporting (ie load profiling).
These new metrics often translate into new metering device functions, enhanced capabilities, and complex communication protocols.
Inevitably implementing new device performance capabilities with rigorous performance expectations takes time to design and implement in a new metrological device.
Time to market is, of course, critical for both the meter utility companies and the solution providers.
It is thus imperative that new metering designs integrate enough capabilities to accommodate emerging industry demands.
The metering devices must also provide the utmost flexibility to save design time.
The MAXQ3180's integrates the capabilities demanded for today's most advanced energy-measurement IC.
It provides reactive and power-factor measurements for which some utilities may bill.
It delivers the critical ampere-hour measurements, plus peak current and voltage measurements.
The device gives instantaneous power for peak demand calculations.
The complex communication protocols are managed by a host microcontroller through a standard SPI interface.
The MAXQ3180 integrates more metering features than any single competitive device.
It meets the demanding performance specifications of today's electricity metering industry while operating at the lowest power.
The MAXQ3180 is packaged in a 28-pin TSSOP package and operates over the -40 to +85C temperature range.
Three-phase power-meter reference designs are available to speed designs and reduce time to market.
Prices start at US $5.25 (1000-up).
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