JAJSDD3B June 2017 – January 2019 TPS53681
PRODUCTION DATA.
As shown in the Overview section, in 8-phase continuous conduction mode, the device operates as described in Figure 5.
Starting with the condition that the high-side FETs are off and the low-side FETs are on, the summed current feedback (VISUM) is higher than the summed error amplifier output (VCOMP) and the internal ramp signal (VRAMP). ISUM falls until it hits VCOMP+VRAMP, which contains a component of the output ripple voltage. The PWM comparator senses where the two waveforms cross and triggers the on-time generator. This generates the internal CLKA_ON signal. Each CLKA_ON signal corresponds to one switching ON pulse for one phase.
In case of single-phase operation, every CLKA_ON signal generates a switching pulse on the same phase. Also, VISUM corresponds to just a single-phase inductor current.
In case of multi-phase operation, the CLKA_ON signal gets distributed to each of the phases in a cycle. This approach of using the summed inductor current and cyclically distributing the ON pulses to each phase automatically gives the required interleaving of 360 / n, where n is the number of phases.