Part # Application Notes Utility Metering Power Supply And Power Management ST7LITE20F2 ST7LITE25F2 ST7LITE29F2 ST7LITE30F2 ST7LITE35F2 datasheet

Part Manufacturer: ST Microelectronics

ST Microelectronics

Part Description: Single-Phase Energy Meter with Tamper Detection based on ST7Flite2x


Part Details:

AN2288 Application note Single-phase energy meter with tamper detection based on ST7FLITE2x Introduction This application note describes the design for a single-phase power / energy meter with tamper detection. The design measures active power, voltage, current, power factor and line frequency in a single-phase distribution environment and displays active energy, voltage, current, power factor, line frequency, current date and time. It differs from ordinary single-phase meters in that it uses two current transformers (CT) to measure active power in both live and neutral wires. This enables the meter to detect, signal, and continue to measure the active energy consumed reliably even when subject to external tamper attempts. ST7FLITE20 is the microcontroller used to perform all the measurements in the meter. As the ST7FLITE30 is pin-to-pin compatible with ST7FLITE20, the ST7LITE30 can also be used in this application (replacing the ST7LITE20) but a revalidation is required for finding the accuracy class of the meter. The active energy consumed is available in the form of frequency-modulated pulse outputs and the accumulated active energy on an LCD display module. Additional features for both consumer types can also be incorporated. These include multiple tariff rates and improved communications, through which meter readings can be taken with less time and with higher accuracy. May 2006 Rev 1 1/29 www.st.com Contents AN2288 Contents 1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3 Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 3.1 Analog front end . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 4 Meter hardware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 4.1 Main blocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 4.1.1 5V power supply block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 4.1.2 2.5V reference block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 4.1.3 Current transformer block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 4.1.4 Voltage divider block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 4.1.5 Tamper detection block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 4.1.6 Gain switching block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 4.1.7 EEPROM block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 4.1.8 RTC block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 4.1.9 LCD module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 4.1.10 In-Circuit Programming block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 4.1.11 Calibration through PC GUI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 4.1.12 Microcontroller block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 5 Software routines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 5.1


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Application Notes Utility Metering Power Supply And Power Management ST7LITE20F2 ST7LITE25F2 ST7LITE29F2 ST7LITE30F2 ST7LITE35F2.pdf Datasheet