Patent ID: 8129970

Claim:
A switching regulator, comprising: an inductor configured to store charge from an input voltage terminal; a first step-down switch configured to switch to store a charge in the inductor at a step-down operation in accordance with a first control signal; a second step-down switch configured to discharge the charge stored in the inductor in the step-down operation in accordance with a second control signal; a first step-up switch configured to switch to store a charge in the inductor at a step-up operation in accordance with a third control signal; a second step-up switch configured to discharge the charge stored in the inductor in the step-up operation in accordance with a fourth control signal; a reverse current detector configured to detect a reverse current from an output terminal to the inductor through the second step-up switch; and a controller configured to control the first and second step-down switches and the first and second step-up switches to output a predetermined constant voltage at an output terminal, and to shut off the second step-up switch when the detector detects the reverse current or an indication of the reverse current, wherein the reverse current detector has a threshold value in the step-down operation for determining an occurrence of the reverse current or an indication of the reverse current and a threshold value in the step-up operation for determining an occurrence of the reverse current or an indication of the reverse current, wherein the reverse current detector comprises a comparator that checks the voltage difference between both terminals of the second step-up transistor and changes an input offset voltage in accordance with an operation mode of the comparator, and wherein the threshold value in step-up and step-down operations is determined to be the input offset voltage.