ST7MC2S4TC datasheet(160/308 Pages) STMICROELECTRONICS

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ST7MC1/ST7MC2

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MOTOR CONTROLLER (Cont’d)

In conclusion, there are 4 sampling types that are

available for Z event detection in sensorless

mode.

1. Sampling at the end of the OFF time of the

PWM signal at the PWM frequency

2. Sampling, at a programmable frequency inde-

pendent of the PWM state (during ON time or

OFF time of the signal). Sampling is done at

fSCF, see Table 82.

3. Sampling during the ON time of the PWM sig-

nal by adding a delay at PWM frequency

4. Sampling, at a programmable frequency during

the ON time (addition of a programmable delay)

of the PWM signal. Sampling is done at fSCF,

see Table 82.

Note 1: The sampling type is applied only for Z

event detection after the D event has occured.

Whatever the sampling type for Z event detection,

the sampling of the signal for D event detection is

always done at the selected fSCF frequency (see

Table 82), independently of the PWM signal (ei-

ther during ON or OFF time). Table 34 explains the

different sampling types in sensorless and in sen-

sor mode.

Note 2: When the MOE bit in the MCRA register is

reset (MCOx outputs in reset state), and the SR bit

in the MCRA register is reset (sensorless mode)

and the SPLG bit in the MCRC register is reset

(sampling at PWM frequency) then, depending on

the state of the ZSV bit in the MSCR register, Z

event sampling can run or be stopped (and D

event is sampled).

Note 3: When BEMF sampling is performed at the

end of the PWM signal off-time, the inputs in OFF-

state are grounded or put in HiZ as selected by the

DISS bit in the MSCR register.

Note 4: The ZEF[3:0] event counter in the MZFR

Figure 86. Sampling during ON time at fSCF

PWM OFF

state

Current

sample

fSCF

PWM signal

DS[3:0]

during

ON time

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