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

UM1855

Figure 14. Power measurement principle schematic diagram

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
All manuals and user guides at all-guides.com
Figure 15 shows an extract of the corresponding schematic diagram.
do not connect AC mains!

Figure 15. STPMS2L power metering schematic diagram

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