SNVSBK2 September 2019 LP8733
Under heavy load conditions, the dual-phase converter switches both channel 180° apart. As a result, the dual-phase converter has an effective ripple frequency two times greater than the switching frequency of a single phase. However, the parallel operation decreases the efficiency at light load conditions. In order to overcome this operational inefficiency, the LP8733xx can change the number of active phases to optimize efficiency for the variations of the load. This is called phase adding and shedding. The concept is shown in Figure 9.
The converter can be forced to dual-phase operation by the BUCK0_FPWM_MP bit in the BUCK0_CTRL_1 register. If the regulator operates in forced dual-phase mode the forced PWM operation is automatically used. If the dual-phase operation is not forced, the number of phases are added and shedded automatically to follow the required output current.
Interleaving switching action of the converters and channels in a 2-phase configuration is shown in Figure 10.