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ST chip with all core circuitry requirements of electricity meters

Posted: 01 Jul 2005 ?? ?Print Version ?Bookmark and Share

Keywords:stmicroelectronics? st? stpm01?

STMicroelectronics (ST) announced the availability of a new device that incorporates all of the core circuitry required to implement fully electronic electricity meters.

Jointly developed by ST and ISKRAEMECO, the STPM01 is a standard device modified from an ASIC solution built for ISKRAEMECO using ST's advanced BCD6 smart power technology, allowing all of the necessary analog, digital and power circuits to be integrated on a single chip. The major blocks include analog signal conditioning, two Analog-to-Digital Converters, a hardwired dedicated Digital Signal Processor (DSP), an SPI interface to an external MCU, a block of 56 OTP (One Time Programmable) bits for calibration and configuration, a Voltage-to-Frequency converter to drive a stepper motor display in low-end applications, and two current-limited, low-drop voltage regulators to supply the analog (3V) and digital (1.5) circuitry.

According to the two companies, the STPM01 addresses a wide range of electricity metering requirements, operating as a stand-alone power meter in the simplest low-end equipment or as a peripheral in sophisticated microprocessor-based meters that support functions such as remote metering, reactive power measurement, multiple tariffs and tamper detection.

The SPI interface is used to control, configure and calibrate the device using the OTP block and to transmit the digital output data to an external MCU, which handles data collection and management in high-end applications. In addition, the computed power values are also converted internally into pulses to directly drive stepper motor displays in the most cost-sensitive low-end applications.

The OTP block, which is accessible via a simple PC interface and software, allows fast and accurate calibration of the voltage and current sensors, phase correction and temperature drift. Additional features of the STPM01 include Live and Neutral wire current monitoring for tamper detection in secure energy meters; LED drivers to indicate power, tamper detection and no-load conditions; and a zero-crossing signal that can be used to avoid arcing when switching heavy inductive loads in industrial control applications.

The STPM01 offers high performance in terms of accuracy, allowing full compliance with the IEC62052-11 and IEC62053-2X specifications for single-phase class 0.5 wattmeters, while a Synchronisation pin also supports three-phase metering applications. The device operates over a wide range of mains voltage (40VRMS to 300VRMS) and line frequency (45Hz to 65Hz), and can measure up to 200ARMS. In addition to the lower component cost due to the high level of integration, the STPM01 also reduces hidden manufacturing costs associated with calibration, thanks to the fast, tamper-proof OTP block.

The STPM01 is priced at approximately $2 in quantities of 1,000 pieces.

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