Patent ID: 8773099
Filing Date: 2014-07-08
Classification: H02M,Y02B

Abstract:
1. A constant on-time DC-to-DC converter comprising: a regulation control circuit configured to regulate an output voltage generated at an output of a switching circuit supplied by an input voltage, based on generating high-side and low-side pulses for driving high-side and low-side switches, respectively, in the switching circuit according to a switching cycle that has a variable on-time for the low-side switch and, for a normal mode of operation, a constant on-time for the high-side switch; a feedback circuit configured to provide a regulation feedback signal to the regulation control circuit, for controlling the variable on-time of the low-side switch as needed to maintain regulation of the output voltage; and an on-time control circuit included in said regulation control circuit that is configured to decrease output voltage ripple in the output voltage during a power saving mode of operation by shortening the on-time of the high-side switch, as compared to the constant on-time used for the high-side switch during the normal mode of operation, the on-time control circuit comprising wherein the feedback circuit includes an additional current circuit that provides a decaying current after each low-side pulse, such that more decay occurs during extended switching cycles used in power saving mode, and wherein said charging current varies inversely to said decaying current; and wherein said regulation control circuit is configured to enter said power saving mode of operation responsive to detecting light load conditions and to reduce switching losses in said switching circuit while operating in the power saving mode by inserting a variable dead time into the switching cycle.