Circuit description
UM1996
18/29
DocID028716 Rev 2
4.3
BEMF detection circuit
The X-NUCLEO-IHM08M1 expansion board provides two hardware solutions for motor
position measurement: one based on sensors (refer to
Hall/Encoder motor speed sensor
)
and other based on sensorless detection.
In 6-step driving mode, one of the three phases is left in the high-impedance state and we
can detect BEMF zero-crossing events by comparing the voltage of this phase with the
center-tap voltage. This signal is acquired through an analog circuit embedded on the
board, as shown below.
Figure 17: X-NUCLEO-IHM08M1
–
BEMF detection circuit
The X-NUCLEO-IHM08M1 expansion board provides the hardware for bus voltage sensing
and temperature measurement. This signal is acquired with a resistor divider and with an
embedded NTC (placed close to STL220N6F7 Power MOSFET), as shown below.
Figure 18: X-NUCLEO-IHM08M1
–
VBUS and temperature sensing circuit
