SLLSFH8B August 2021 – February 2022 MCT8316A
The MCT8316A offers four methods of directly controlling the speed of the motor. The speed control method is configured by SPD_CTRL_MODE. The speed command can be controlled in one of the following four ways.
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 8-14.
Figure 8-15 shows the relationship between DUTY CMD and SPEED REF / TARGET DUTY.
When speed loop is enabled, DUTY CMD sets the SPEED REF in Hz. MAX_SPEED sets the SPEED REF at DUTY CMD of 100%. MIN_DUTY sets the minimum SPEED REF (MIN_DUTY x MAX_SPEED). SPEED REF stays clamped at (MIN_DUTY x MAX_SPEED) for ZERO_DUTY_THR < DUTY CMD < MIN_DUTY.
When speed loop is disabled, DUTY CMD sets the TARGET DUTY in % - TARGET DUTY is 100% when DUTY CMD is 100% and TARGET DUTY is equal to MIN_DUTY when DUTY CMD is set to MIN_DUTY. TARGET DUTY stays clamped at MIN DUTY for ZERO_DUTY_THR < DUTY CMD < MIN_DUTY.
ZERO_DUTY_THR sets the DUTY CMD below which SPEED REF/ TARGET DUTY (speed loop enabled/disabled) is set to zero and motor is in stopped state. AVS, CL_ACC configure the transient characteristics of DUTY OUT; the steady state value of DUTY OUT is directly configured in % through TARGET DUTY (when speed loop is disabled) or through SPEED REF (when speed loop is enabled).