A switching power regulator for performing DC-to-DC conversion may be implemented with a soft-start circuit configured to ensure orderly power-up of the switching power regulator by controlling the maximum output current delivered to a load while maintaining proper voltage regulation during start-up. The soft-start circuit may use combinations of reference voltages generated by a reference voltage digital-to-analog converter and a programmable width burst-pulse to control an output voltage of the switching power regulator during start-up without requiring external components. The soft-start circuit may provide burst-pulses directly to a drive circuit configured in the switching power regulator to control the output voltage of the switching power regulator, thereby beginning to ramp up the output voltage of the switching power regulator from zero volts. A specified number of clock cycles after the output voltage has reached a specified value, the soft-start circuit may switch control of the drive circuit from the burst pulses to regular PWM or PFM operating modes.
This application claims benefit of priority of U.S. provisional application Ser. No. 60/691,981 titled "Softstart Circuit for a DC to DC Converter", invented by Yu-En Tzeng and filed on Jun. 16, 2005, which is hereby incorporated by reference as though fully and completely set forth herein.
