MCT8316A has a speed loop option which can be used to maintain constant speed under varying operating conditions. Speed loop is enabled by setting CLOSED_LOOP_MODE to 01b. K_p and K_i coefficients are configured through SPD_POWER_KP and SPD_POWER_KI. The output of speed loop (SPEED_PI_OUT) is used to generate the DUTY OUT (see Figure 8-14). The PI controller output upper (V_MAX) and lower bound (V_MIN) saturation limits are configured through SPD_POWER_V_MAX and SPD_POWER_V_MIN respectively. When output of the speed loop saturates, the integrator is disabled to prevent integral wind-up. The speed loop PI controller is as in Figure 8-32.

SPEED_REF is derived from duty command input and maximum motor speed (MAX_SPEED) configured by user (see Equation 6). In speed loop mode, minimum SPEED_REF is set by MIN_DUTY * MAX_SPEED.