ST0942 Single 3.3V 10mW Calibration-Free Single-Phase Energy Metering IC with UART Cascading

ST0942 Single 3.3V 10mW Calibration-Free Single-Phase Energy Metering IC with UART Cascading

ST0942

The ST0942 is a calibration-free energy metering IC with an integrated on-chip clock oscillator, combining two independent Sigma-Delta ADCs (one for current, one for voltage), an internal voltage reference, power management and a DSP engine. It measures current/voltage RMS, active power and active energy over a current range of 10mA~30A @ 1mΩ and an active energy range of 1W~6600W @ 1mΩ @ 220V. The IC provides fast current RMS output for over-current protection, waveform data output, and voltage/current zero-crossing detection output. Communication runs over UART (4800~38400 bps) or SPI (up to 900 kHz), and the TSSOP14L package supports up to 4 devices cascaded on a single UART bus. Factory gain error is below 1%, and no calibration is needed when external discrete components meet specified conditions. Operating from a single 3.3V supply at 10mW typical and offered in SOP8, SSOP10L and TSSOP14L packages, the ST0942 is widely used in single-phase multifunction energy meters, smart sockets, smart home appliances and power consumption data acquisition systems.

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Specifications

MeasurementBuilt-in clock calibration-free single-phase energy metering: RMS current/voltage, fast current RMS (over-current protection), active power/energy, waveform data output; current 10mA~30A@1mΩ, energy 1W~6600W@1mΩ@220V
Power Consumption10 mW (typ, single 3.3V)
ADC Channels2 independent Sigma-Delta ADCs (one current, one voltage)
OutputUART/SPI (SPI up to 900 kHz, UART 4800~38400 bps, up to 4 devices cascaded on TSSOP14L); zero-crossing detection output
ClockBuilt-in oscillator, approx. 4 MHz
VDDSingle 3.3V
CalibrationFactory gain error <1%
FreeCalibration-free when external discrete components meet specified conditions
PackageSOP8 / SSOP10L / TSSOP14L

Product details

Overview

The ST0942 is a calibration-free energy metering IC with an integrated on-chip clock oscillator, designed for single-phase multifunction energy meters, smart sockets, smart home appliances and similar applications requiring high cost-performance. It integrates two high-precision Sigma-Delta ADCs, an internal voltage reference, power management and other analog building blocks, along with a DSP engine for computing active power, current/voltage RMS and other electrical parameters. The ST0942 measures current/voltage RMS, active power, active energy and other key parameters, and provides a fast current RMS output for over-current protection plus waveform data output. Communication is supported via UART/SPI interfaces, fully meeting the requirements of smart sockets, smart home appliances, single-phase multifunction energy meters and power consumption data acquisition systems; the TSSOP14L package further supports up to 4 devices cascaded on a single UART bus for multi-circuit metering expansion. Its patented anti-creep design, in conjunction with proper external hardware, ensures noise-induced power is not accumulated into energy pulses under no-load conditions. Factory gain error is below 1%, and calibration is unnecessary when external discrete components meet specified conditions.

Features

  • Two independent Sigma-Delta ADCs, one for current and one for voltage
  • Current RMS measurement range 10mA~30A @ 1mΩ
  • Active energy measurement range 1W~6600W @ 1mΩ @ 220V
  • Current/voltage RMS, fast current RMS and active power output
  • Factory gain error <1%; calibration-free when external components meet specified conditions
  • Current channel over-current detection with configurable threshold and response time
  • Voltage/current zero-crossing detection output
  • Integrated waveform registers for load characterization and analysis
  • SPI (max clock 900kHz) / UART (4800~38400 bps) communication; TSSOP14L supports up to 4 devices cascaded on a single UART bus
  • Power-down detection with device reset below 2.7V; integrated 1.218V voltage reference
  • Integrated on-chip oscillator, approx. 4MHz
  • Single 3.3V supply, 10mW typical power consumption; SOP8/SSOP10L/TSSOP14L packages

Typical Applications

  • Single-phase multifunction energy meters
  • Smart sockets
  • Smart home appliances
  • Multi-circuit power consumption data acquisition systems

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