STPM14 STMicroelectronics, STPM14 Datasheet - Page 18

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

Theory of operation
Figure 16. Bandgap temperature variation
7.7
Table 11.
18/43
LTCH
0
1
2
3
Load monitoring
The STPM1X include a no-load condition detection circuit with adjustable threshold. This
circuit monitors the voltage and the current channels and, when the measured power 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 VRMS and IRMS input values is
below a given value. This value can be set with the LTCH configuration bits, and it is also
dependent on the selected current gain (Ai) and the calibration registers constant Kp=Kv*Ki.
Four different no-load threshold values can be chosen according to the two configurations
bits LTCH (see
No load detection thresholds
When a no-load condition occurs (BIL=1), the integration of power is suspended and the
tamper module is disabled.
If a no-load condition is detected, the BIL signal blocks generation of pulses for stepper and
forces the SCLNLC pin to be low.
Vrms * Irms (input channel voltages)
Rogowski coil (PST<2)
0.004488 / (Ai*Kp)
0.008976 / (Ai*Kp)
0.017952 / (Ai*Kp)
0.035904 / (Ai*Kp)
Table 11.
).
Vrms * Irms (input channel voltages)
Ct or Shunt (PST>1)
0.003648 / (Ai*Kp)
0.007296 / (Ai*Kp)
0.014592 / (Ai*Kp)
0.029184 / (Ai*Kp)
STPM11/12/13/14