STPM11 STMicroelectronics, STPM11 Datasheet - Page 14

• Manufacturer Part Number: STPM11
• Description: Single phase energy metering IC with pulsed output and digital calibration
• Manufacturer: STMicroelectronics

Theory of operation
Table 7.
Table 8.
7.3
14/43
Gain
16
24
32
32
8
8
Gain
Configuration of current sensors
Configuration of current sensors
16
24
32
32
The
Both the voltage and current channels implement an active offset correction architecture
which has the benefit of avoiding any offset compensation.
The analog voltage and current signals are processed by the ∑ ∆ Analog to digital converters
that feed the hardwired DSP. The DSP implements an automatic digital offset cancellation
that makes possible avoiding any manual offset calibration on the analog inputs.
∑ ∆ A/D Converters
The analog to digital conversion in the STPM1X is carried out using two first order ∑ ∆
converters. The device performs A/D conversions of analog signals on two independent
channels in parallel. In STPM13/14, the current channel is multiplexed as primary or
secondary current channel in order to be able to perform a tamper function. The converted
∑ ∆ signals are supplied to the internal hardwired DSP unit, which filters and integrates
those signals in order to boost the resolution and to yield all the necessary signals for
computations.
8
8
Primary
Table 7.
Rogowsky Coil
Current channel
Sensor
CT
and
Table 8.
Rogowsky Coil
Sensor
Shunt
: below show the gain values according to the configuration bits:
CT
Gain
16
24
32
32
8
8
Secondary
STPM11/12
STPM13/14
Rogowsky Coil
Sensor
Shunt
CT
PST (2bits)
0
0
1
1
2
3
Configuration Bits
PST (2bits)
0
0
1
1
2
3
Configuration Bits
ADDG (1 bit)
STPM11/12/13/14
ADDG (1 bit)
0
1
0
1
x
x
0
1
0
1
x
x