Patent ID: 7116089

Claim:
A switching regulator for controlling an output voltage configured to feed a load, wherein the switching regulator operates in pulse-width modulation (PWM) mode when the load current is higher than a predetermined value and operates in pulse-frequency modulation (PFM) mode when the load current is lower than the predetermined value, the switching regulator comprising: an input voltage port for supplying input voltage V IN to the switching regulator; an output voltage port for providing a regulated output voltage V OUT to the load; a switch SW, connected to the output voltage port for turning the output voltage on and off, wherein SW is partly controlled by a feedback signal representing V OUT ; a feedback port FB to which a predetermined portion of the output voltage V OUT (V FB ) is connected; an inductor L, connected between the input voltage port and the output voltage port; a clock pulse generator; an error amplifier; a PWM comparator; a feedback comparator; a light-load comparator; and a configuration wherein: in PWM mode, at the beginning of each clock cycle switch SW is turned on to increase a current in the inductor L (I L ) which is converted to a voltage V IPK and is compared to a control voltage V CONTRL by the PWM comparator to turn off switch SW when V IPK =V CONTROL , wherein V CONTRL is generated by comparing V FB to an internal reference voltage V REF using the error amplifier; and in PFM mode, the feedback comparator compares V OUT , using V FB , to V REF and if V OUT <V REF , SW is turned on forcing I L to rise, where I L is converted to the voltage V IPK and is compared to a first reference voltage V IMIN by the light-load comparator and if V IPK =V IMIN SW is turned off forcing I L to charge up the output voltage V OUT and wherein V IMIN is a predetermined voltage, and wherein the switching regulator keeps idling until V FB drops to V REF .