Rather than operating in asynchronous mode during turn-on ramps, a
switching power regulator system may be configured to synthesize a
digital waveform, which may protect against a pre-bias condition and
maintain the desired ramp-up time and rate. The desired turn-on ramp may
be generated digitally by counter logic, beginning with an initial value
and incrementing at a programmed rate until a digital value equivalent to
the desired output voltage is reached. When a pre-bias condition is not
present, the output of the digital ramp generator may control a
digital-to-analog converter (DAC), which may be configured to generate
the reference voltage for the power regulator. To correct for a pre-bias
condition, the pre-bias output of the power regulator may be measured
prior to turn-on, using an analog-to-digital converter. The digital
pre-bias value may be used to control the DAC until the value of the
digital waveform generated by the ramp generator reaches the pre-bias
value.