Patent ID: 8917073

Claim:
A switching mode power supply (SMPS) configured to supply a load, the SMPS comprising: a switch, having a control end; an output port, configured to provide an output voltage, wherein the output voltage is regulated under the switching action of the switch, wherein the output port is coupled to the load, and wherein the output port is further configured to provide a voltage feedback signal indicating the output voltage and a current feedback signal indicating an output current of the load; an on-time generator, having an input end and an output end, wherein the input end is configured to receive the current feedback signal, and wherein the output end is configured to provide a time signal indicating an on time period; and a pulse width modulation (PWM) generator, having a first input end, a second input end and a first output end, wherein the first input end is configured to receive the voltage feedback signal, the second input end is configured to receive the time signal, and the output end is configured to provide a PWM signal that is coupled to the control end of the switch, and further wherein the PWM signal is configured to turn ON the switch when the voltage feedback signal is lower than a threshold voltage, and the PWM signal is configured to turn OFF the switch at an end of the on time period; wherein the output current is scaled into multiple levels, and wherein each of the multiple levels corresponds to a respective on time period, and further wherein the on time period increases when the output current increases; and wherein the on-time generator comprises: a plurality of comparing circuits, each of the plurality of comparing circuits is configured to compare the current feedback signal with a respective reference signal, and each of the plurality of comparing circuits is further configured to output a respective load indication signal; and a timer, having a plurality of input ends and an output end, wherein each of the plurality of input ends is configured to receive the respective load indication signal and the PWM signal, and wherein the output end is configured to provide the time signal based on the load indication signals and the PWM signal.