AN1905 ST Microelectronics, Inc., AN1905 Datasheet - Page 58

• Manufacturer Part Number: AN1905
• Description: St7mc Three-phase BLDC Motor Control Software Library
• Manufacturer: ST Microelectronics, Inc.

ST7MC THREE-PHASE BLDC MOTOR CONTROL SOFTWARE LIBRARY
7.2.3.2 At PWM On, with delay once
This method requires additional external components (resistor dividers, with/without RC fil-
tering). Samples are taken once, each PWM ON time, after a delay programmed by DS[3:0]
bits in MCONF register. Duty cycle variation induces jitter on the sampling clock; if the system
stability is affected, sampling should then be done at
100% duty cycle can be set.
Figure 39. Sampling during ON time, at PWM frequency
7.2.3.3 At PWM On, with delay, at
This method requires additional external components (resistor dividers, with/without RC fil-
tering). Samples are taken at
grammed by DS[3:0] bits in MCONF register. True 100% duty cycle can be set.
Figure 40. Sampling during ON time at f
7.2.3.4 At
This method requires additional external components (resistor dividers, with/without RC fil-
tering). The sampling is done at a programmable frequency independent of the PWM state.
Samples are taken at
are driven with Pulse Amplitude Modulation (PAM).
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PWM signal
f
SCF
frequency
PWM signal
f
SCF
frequency. This type of sampling might be chosen when the motors
state
PWM OFF
f
SCF
T
Sampling
DS[3:0]
frequency, during PWM ON time and after a delay pro-
f
PWM OFF
time
SCF
DS[3:0]
frequency
f
during
ON time
SCF
SCF
Current
sample
DS[3:0]
Current
sample
DS[3:0]
f
SCF
frequency (see next section). True
sample
New