STPM01 Datasheet, PDF (21/56 Pages) List of Unclassifed Manufacturers – PROGRAMMABLE SINGLE PHASE ENERGY METERING IC WITH TAMPER DETECTION

STPM01
Theory of operation
A BandGap voltage reference (VBG) of 1.23V ±1% is used as reference voltage level source
for the two linear regulators and for the A/D converters. Also, this module produces several
bias currents and voltages for all other analog modules and for the OTP module. The
bandgap voltage can be compensated regardless to the temperature variations with the
BGTC bits..
Figure 17. Bandgap temperature variation
8.8
Load monitoring
The STPM01 includes a no load condition detection circuit with adjustable threshold. This
circuit monitors the voltage and the current channels and, when the measured voltage is
below the set threshold, the internal signal BIL becomes high. The information about this
signal is also available in the status bit BIL.
The no load condition occurs when the product between V_RMS and IRMS register values is
below a given value. This value can be set with the LTCH configuration bits.
Four different no-load threshold values can be chosen according to the two configuration
bits LTCH (see table 11).
Table 11. No load detection thresholds
LTCH
0
1
2
3
K_LTCH
800
1600
3200
6400
When a no load condition occurs (BIL=1) the integration of power is suspended and the
tamper module is disabled.
In standalone mode, if a no load condition is detected, the BIL signal blocks generation of
pulses for stepper and forces SCLNLC pin to be low. If APL=2 (see 8.14) the LED pin
continues providing the high frequency pulses, while if APL=3, the pulses are stopped as
happens for MOP and MON.
In peripheral mode, the BIL signal can be accessed only through the SPI interface.
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