STPM14 STMicroelectronics, STPM14 Datasheet - Page 35

• Manufacturer Part Number: STPM14
• Description: (STPM11 - STPM14) Single phase energy metering IC
• Manufacturer: STMicroelectronics

STPM11/12/13/14
9
Table 16.
Table 17.
Line RMS voltage
Line RMS current
Power sensitivity
Shunt Sensor
Reference voltage
Clock
Amplification of ADC
Gain of voltage and current decimation filters
Calibration data range
AW Bit position that generates LED signal
STPM1X Calibration
Energy meters based on STPM1X devices are calibrated on the frequency of the output
pulse signal.
The devices are comprised of two independent meter channels for line voltage and current
respectively. Each channel includes its own digital calibrator, to adjust the voltage and
current signals coming from the sensors in the range of ±12.5% in 256 steps. A digital filter
is included to remove any signal DC component.
The devices produce an energy output pulse signal whose frequency is proportional to the
measured active energy.
The devices have an embedded memory, 54 bits, used for configuration and calibration
purposes. The value of these bits can be written temporarily or permanently through CFGI
communication channel.
The basic information needed to start the calibration procedure is found in
Table 17.
The following typical STPM01 parameters and constants are also known:
Av is constant. While, Ai is chosen according to the sensor
Gv and Gi are constant
Cv and Ci are 8bits register (CHV, CHP and CHS)
From the values above and for both the given amplification factor and initial calibration data,
the following target values can be calculated:
Considering that Ci=0 generates a correction of 75% and that Ci=128 determines a
correction factor of 87.5%, and the same for Cv, the total correction for the power stands
within Kp = Kv*Ki = (0.75*0.75)=56.25% and 100%, and Cv=Ci=128 gives a correction
factor of Kp= (0.875*0.875) = 76.5625%
Each calibrator value can be changed from a binary form to a decimal correction form, using
the following formula:
:
Vn
In
Si
P
(230 V)
(5 A)
(LED: P=128000 pulses/kWh, Stepper Motor: PM=P/64= 2000 pulses/kWh)
0,42 mv/A
Cv, Ci
Av, Ai
Vbg
Gp
DL
fM
(1.23 V ± 2%)
(2
(4 ± 1%, (8, 16, 24, 32) ± 2%))
(0.504008)
(min = 0, ini = 128, max = 255)
(2
23
11
)
Hz ± 50ppm)
STPM1X Calibration
Table 16.
and
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