STEVAL-IPE012V1 STMicroelectronics, STEVAL-IPE012V1 Datasheet - Page 16

• Manufacturer Part Number: STEVAL-IPE012V1
• Description: EVAL BOARD ENERGY METER
• Manufacturer: STMicroelectronics
• Series: -r

Specifications of STEVAL-IPE012V1

• Design Resources: STEVAL-IPE012V1 Schematic STEVAL-IPE012V1 BOM
• Main Purpose: Power Management, Energy/Power Meter
• Embedded: Yes, MCU, 8-Bit
• Utilized Ic / Part: STPM10BTR, STM8L152
• Primary Attributes: Single Phase with 1 Current Transformer & Shunt
• Secondary Attributes: Tamper Detection
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 497-11462

Theory of operation
Table 6.
Table 7.
Note:
7.3
16/51
Gain
32
8
8
8
Gain
Gain of voltage and current channels
The gain register is included in the device configuration register with the address name
PST. The table below shows the gain configuration according to the register values:
Configuration of current sensors
If the device is used in configuration PST = 1, TMP = 1 (primary channel with CT, secondary
channel with Shunt), the shunt Ks must always be equal to one fourth of the current
transformer Ks.
Both the voltage and current channels implement an active offset correction architecture
which provides the benefit of avoiding any offset compensation.The analog voltage and
current signals are processed by the Σ Δ analog-to-digital converters, which feed the hard-
wired DSP. The DSP implements an automatic digital offset cancellation that makes it
possible to avoid any manual offset calibration on the analog inputs.
ΣΔ A/D converters
Analog-to-digital conversion in the STPM10 is carried out using two first-order Σ Δ
converters. The device performs A/D conversions of analog signals on two independent
channels in parallel. The current channel is multiplexed as a primary or secondary current
channel in order to perform the tamper function, if enabled. The converted Σ Δ signals are
supplied to the internal hard-wired DSP unit, which filters and integrates these signals in
order to boost the resolution and to yield all the necessary signals for the computations.
A Σ Δ modulator converts the input signal into a continuous serial stream of 1’s and 0’s at a
rate determined by the sampling clock. In the STPM10, the sampling clock is equal to
f
The 1-bit DAC in the feedback loop is driven by the serial data stream. The DAC output is
subtracted from the input signal. If the loop gain is high enough, the average value of the
DAC output (and therefore the bit stream) can approach that of the input signal level. When
a large number of samples are averaged, a very precise value for the analog signal is
obtained. This averaging is carried out in the DSP section, which implements decimation,
4
CLK
Primary
/4.
Voltage channels
Sensor
Shunt
CT
CT
Max input voltage (V)
±0.30
Disabled
Disabled
Gain
32
8
Doc ID 17728 Rev 3
Secondary
Disabled
Disabled
Sensor
Shunt
CT
Gain
32X
8X
Current channels
Configuration
PST
Bits
0
1
0
1
Max input voltage (V)
±0.035
Configuration
±0.15
TMP
Bits
0
0
1
1
STPM10