STEVAL-IPE012V1 STMicroelectronics, STEVAL-IPE012V1 Datasheet - Page 15

• 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

STPM10
7
7.1
7.2
Theory of operation
General operation description
The STPM10 is capable of performing measurements of active, reactive and apparent
energy, RMS and instantaneous voltage and current values, and line frequency information.
Most of the functions are fully programmable using internal configuration bits accessible
through the SPI interface. The STPM10 works as a peripheral in microcontroller-based
metering systems. The ZCR and WDG pins are used to provide zero-crossing and watch-
dog information, and the SPI pins are used to communicate with the microcontroller.
The STPM10 includes volatile internal registers that hold the useful information for the
metering system. Two kinds of active energy are available: wide-band active energy (AW)
which includes all harmonic content (also called type 0) and fundamental active energy
(AF), limited to the 1st harmonic (also called type 1). This latter energy value is obtained by
filtering type 0 active energy. Both the two active energies are stored in up-down counting
accumulator registers with a 20-bit length. Reactive and apparent energies are also
available with a 20-bit accumulation.
The STPM10 also provides the RMS values for voltage and current. Due to the modest
dynamic variation of the voltage, the RMS value is stored with a resolution of 11 bits, while
the RMS current value has a resolution of 16 bits. The instantaneous (momentary) sampled
value of voltage and current are also available with a resolution of 11 and 16 bits,
respectively. The line frequency value is stored with a resolution of 14 bits.
Due to the proprietary energy computation algorithm, the STPM10 calibration is quick and
simple, allowing calibration at only one point over the entire current range.
The configuration and calibration parameters must be downloaded in the internal non-
volatile memory of STPM10 at power-up.
Analog inputs
Input amplifiers
The STPM10 has one fully differential voltage input channel and two fully differential current
input channels.
The voltage channel consists of a differential amplifier with a gain of 4. The maximum
differential input voltage for the voltage channel is ± 0.3 V.
The two current channels are multiplexed (see
input to a preamplifier with a gain of 4. The output of this preamplifier is connected to the
input of a programmable gain amplifier (PGA) with possible gain selections of 2 and 8. The
total gain of the current channels are then 8 and 32. The gain selections are made by writing
to the gain register, and they can be different for the two current channels. If the tamper
function is not used, the secondary current can be disabled.
The maximum differential input voltage is dependent on the selected gain, in accordance
with
Table
6.
Doc ID 17728 Rev 3
Chapter 7.9
for details) to provide a single
Theory of operation
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