DC/DC converter including ultrasonic feature for use with low quiescent currents

摘要

A buck voltage converter comprises an upper switching transistor connected between an input voltage node and a phase node. The upper switching transistor turns on and off responsive to a first drive signal. A lower switching transistor is connected between the phase node and ground. The lower switching transistor turns on and off responsive to a second drive signal. An inductor is connected the phase node and an output voltage node. Control circuitry generates the first drive signal and the second drive signal responsive to a feedback voltage monitored at the output voltage node and a phase at the phase node. In a pulse frequency mode voltage of operation the control circuitry turns off the upper switching transistor and turns on the lower switching transistor responsive to a determination that a predetermined period of time has occurred since a detection of a phase switch at the phase node and turns off both the upper switching transistors and the lower switching after the lower switching transistor has been turned on for a second predetermined period of time.