Figure 14. Power Measurement Principle Schematic Diagram; Figure 15. Stpms2L Power Metering Schematic Diagram - STMicroelectronics STM32L476G-EVAL User Manual

UM1855
A low-voltage AC generator is to be applied by the user as shown in
resistor is connected in series with the load to provide current measurement points to one of
STPMS2L input channels. The voltage measurement points for the other input channel are
taken across the load.
Warning:
Test example:
The output of a low-voltage AC generator is connected to CN4, terminals 1 and 3. The
amplitude is set between 200 mV and 300 mV and the frequency adjustable between 10 Hz
and 100 Hz.
With 34 Hz frequency and the load formed of R27 of 1 kΩ in parallel with C29 of 4.7 µF, the
voltage and current phases are theoretically 45 degrees apart.
STPMS2 power metering
external generator input: pins 1 and 3
voltage of complex load: pins 2 and 3
shunt voltage

Figure 14. Power measurement principle schematic diagram

Figure 15 shows an extract of the corresponding schematic diagram.
do not connect AC mains!

Figure 15. STPMS2L power metering schematic diagram

CN4
1
2
3
GND
: pins 1 and 2
R+jX Load
DocID027351 Rev 3
Hardware layout and configuration
C26
100nF
current
shunt
GND
U3
STPMS2L-PUR
6
CIP
R26
1K
5
CIN
8
VIP
R27
1K
7
VIN
GND
GND
GND
Figure 14. The shunt
C27
VDD
GND
1uF
GND
16
DATn
Exposed
pad GND 15
DAT
14
CLK
13
MS3
GND
C24
1uF
53/100
99