Besides continuos conduction mode (PWM), the TPS63805, TPS63806, and TPS63807 feature power safe mode (PFM) operation to achieve high efficiency at light load currents. This is implemented by pausing the switching operation, depending on the load current.

The skip comparator manages the switching or pause operation. It compares the current demand signal from the voltage loop, I_REF, with the skip threshold, I_SKIP, as shown in Figure 9-1. If the current demand is lower than the skip value, the comparator pauses switching operation. If the current demand goes higher (due to falling V_O), the comparator activates the current loop and allows switching according to the loop behavior. Whenever the current loop has risen V_O by bringing charge to the output, the voltage loop output, I_REF (respectively V_EA), decreases. When I_REF falls below I_SKIP-hysteresis, it automatically pauses again.

Figure 9-10 Power Safe Mode Operation Curves