Soft start for buck converter

An integrated circuit (IC) device comprising:

• a Buck converter;
• and
• a control circuit for the Buck converter, comprising:
• a comparator configured to compare a feedback voltage of the Buck converter with a reference voltage that increases from a first voltage to a second voltage;
• a pulse-width modulator configured to generate a pulse-width modulated (PWM) signal having a timing-varying pulse width that is proportional to a value of the reference voltage;
• an AND gate configured to generate a first control signal by performing a logic AND operation on an output signal of the comparator and the PWM signal;
• a pulse generator configured to generate a second control signal by generating a pulse in response to a rising edge in the output signal of the comparator;
• and
• a selection circuit configured to, based on an output voltage of the Buck converter, select the first control signal or the second control signal as a control signal for the Buck converter.

A method of starting a Buck converter, the method comprising:

• supplying a reference voltage to a control circuit for the Buck converter, wherein the reference voltage increases from a first voltage to a second voltage;
• comparing an output voltage of the Buck converter with a pre-determined threshold;
• in response to detecting that the output voltage of the Buck converter is lower than the pre-determined threshold, driving the Buck converter with a first control signal, wherein the first control signal comprises a first plurality of pulses having a time-varying pulse width that is proportional with the reference voltage;
• and
• in response to detecting that the output voltage of the Buck converter is high than the pre-determined threshold, driving the Buck converter with a second control signal, wherein the second control signal comprises a second plurality of pulses with a pulse width proportional to a ratio between the output voltage of the Buck converter and an supply voltage of the Buck converter.