Patent ID: 7852060

Claim:
A method of forming a buck-boost power supply controller comprising: configuring a switch control section to operate a plurality of switches to control an output voltage wherein the switch control section operates the plurality of switches in one of a buck mode, a boost mode, or a buck-boost mode responsively to a value of the output voltage; configuring the switch control section to form a cycle of the buck-boost mode into three portions wherein the switch control section is configured to operate the plurality of switches to couple an inductor to receive an input voltage but to not supply power to the output voltage during a first portion of the buck-boost mode cycle, to couple the inductor to supply power to the output voltage but not receive the input voltage during a second portion of the buck-boost mode cycle, and to couple the inductor to both receive power from the input voltage and to couple power to the output voltage during a third portion of the buck-boost mode cycle; and configuring the switch control section to form no more than one of the first or second or third portions of the cycle with a first duration having a substantially fixed time interval and to form another one of the first or second or third portions of the cycle with a second duration that is formed responsively to a value of the output voltage.