| The STPM1x family is designed
for effective measurement of active energy in a power line
system using a Rogowski Coil, Current Transformer and Shunt
sensors.
This device is specifically designed to provide all the
necessary features to implement a single phase energy meter
without any other active component. The STPM1x
device family consists, essentially, of two parts: the analog
part and the digital part. The former, is composed of a
preamplifier and first order Σ Δ A/D converter
blocks, band gap voltage reference, low drop voltage regulator.
The digital part is composed of a system control, oscillator,
hard wired DSP and interface for calibration and configuration.
The calibration and configuration are done by OTP cells,
that can be programmed through a serial interface. The configured
bits are used for testing, configuration and calibration
purposes. From two Σ Δ output signals coming from
the analog section, a DSP unit computes the amount of consumed
active energy. The active energy is available as a pulse
frequency output and directly driven by a stepper counter.
In the STPM1X an output signal with pulse
frequency proportional to energy is generated. This signal
is used in the calibration phase of the energy meter application
allowing a very easy approach. When the device is fully
configured and calibrated, a dedicated bit of OTP block
can be written permanently in order to prevent accidental
entry into test mode or changing any configuration bit. |
