Switching converter and oscillator thereof

An oscillator of a switching converter, wherein the oscillator comprises:

• a charging current generating circuit, configured to generate a charging current;
• a clock signal generator circuit, configured to generate a slope voltage according to the charging current, compare the slope voltage with a first reference voltage to obtain a comparison result, and generate a clock signal according to the comparison result,
• wherein, the charging current generating circuit comprises a variable resistor and a current limiting module, which is configured to limit a current value of the charging current to a preset current value when the variable resistor is shorted or opened,
• wherein the charging current generating circuit further comprises:
• a first transistor and a second transistor being connected in series between a power supply voltage and the variable resistor;
• a fourth transistor being connected between the power supply voltage and the clock signal generator circuit, wherein the fourth transistor and the first transistor form a current mirror, and a second terminal of the fourth transistor is used for supplying the charging current;
• and
• an operational amplifier, which has a non-inverting input terminal being used for receiving a second reference voltage, an inverting input terminal being connected to a first node with a first terminal of the variable resistor, and an output terminal being connected to a control terminal of the second transistor,
• wherein, the operational amplifier is configured to provide a feedback adjustment signal to the second transistor according to a node voltage of the first node and the second reference voltage, to adjust the current value of the charging current,
• wherein the current limiting module comprises:
• a first current source, having a first terminal being connected to the power supply voltage and having a second terminal being connected to the first node.