Control circuit and associated method for switching converter

A control circuit for a switching converter, the switching converter having a high switch and a low side switch connected in series, the control circuit comprising:

• an ON signal generating circuit having a first input terminal, a second input terminal and an output terminal, wherein the first input terminal is configured to receive a reference signal, and wherein the second input terminal is configured to receive a feedback signal which indicates an output voltage or a load current of the switching converter, and wherein based on a comparing result between the reference signal and the feedback signal, the ON signal generating circuit provides an ON signal at the output terminal;
• an OFF signal generating circuit, providing an OFF signal, wherein the OFF signal jumps from a first status to a second status when a preset time ends;
• a first comparator having a first input terminal, a second input terminal and an output terminal, wherein based on a comparing result between a first threshold and a current through the high side switch, the first comparator provides a first comparing signal at the output terminal;
• a second comparator having a first input terminal, a second input terminal and an output terminal, wherein based on a comparing result between a second threshold and a current through the low side switch, the second comparator provides a second comparing signal at the output terminal;
• and
• a logic circuit having a first input terminal, a second input terminal, a third input terminal, a fourth input terminal, a first output terminal and a second output terminal, wherein the first input terminal is configured to receive the ON signal, and wherein the second input terminal is configured to receive the OFF signal, and wherein the third input terminal is configured to receive the first comparing signal, and wherein the fourth input terminal is configured to receive the second comparing signal, and wherein based on the ON signal, the OFF signal, the first comparing signal and the second comparing signal, the logic circuit provides a first switching signal to control the high side switch ON and OFF and a second switching signal to control the low side switch ON and OFF, and wherein if the current through the high side switch is smaller than the first threshold when the preset time ends, the high side switch continues turning on till the current through the high side switch is equal to or larger than the first threshold.