The MCF8316A offers four
methods of directly controlling the speed of the motor. The speed control method is
configured by SPEED_MODE. The speed command can be
controlled in one of the following four ways.
- PWM input on SPEED pin by varying
duty cycle of input signal
- Frequency input on SPEED pin by varying frequency of input signal
- Analog input on SPEED pin by
varying amplitude of input signal
- Over I2C by
configuring DIGITAL_SPEED_CTRL register
The speed can also be indirectly
controlled by varying the supply voltage (VM).
The signal path from SPEED pin input (or I2C
based speed input) to output duty cycle (DUTY OUT) applied to FETs is shown in Figure 7-13.
Note:
- Any duty command (DUTY CMD from SPEED pin or I2C) or speed
reference (SPEED REF from speed profiles) value set to < 1% will result
in speed reference (SPEED REF) being clamped to zero and motor to be in
stopped state.
- If MAX_SPEED is set to 0, SPEED REF is clamped to zero (irrespective of
DUTY CMD) and motor is in stopped state.