This user manual describes guidelines to quickly set up a metrology application using the STPM3x devices (STPM32, STPM33 and STPM34) and to access measurement data from the device.
This user manual guides users through setting up metrology applications using STPM32, STPM33, and STPM34 devices. It covers UART and SPI communication protocols, power-on timing, calibration, and register conversion to real values. The manual also includes schematics and software usage details for evaluation boards.
The document provides practical examples for monophase and polyphase systems, including current transformer and shunt sensor configurations. It explains how to calculate power measurements and power factors, and includes a calibration section referencing AN4470 and evaluation software tools.
| Power-on timing | t_if: 4 μs to 10 ms, t_startup: 35 ms, t_rpw: 4 μs to 1 ms, t_scs: 4 μs to 1 ms |
|---|---|
| ADC input range | ±300 mV (with gain A_V), ±150 mV, ±75 mV, or ±37.5 mV (with gains x2, x4, x8, x16) |
To select UART mode, set the SCS signal high before VCC and EN rise, and maintain it high until a couple of clock periods (16 MHz) reach the device.
For non-sinusoidal waveforms, power factor is calculated as P = ∆EACT_WB / ∆EAPP, where Et1 – Et0 are energy values taken in time instants t0 and t1, and t1– t0 time interval is a multiple of a line half-period (10 ms for 50 Hz).