Dc-dc voltage converter system with a high-efficiency pulse-skip operational mode

A voltage converter system to provide an output voltage, comprising:

• a switching voltage converter having an inductor and arranged to switch through said inductor first and second currents with duty cycles determined by a pulse width modulation signal to thereby maintain said output voltage;
• a transconductance amplifier having an amplifier output that provides an error voltage in response to said output voltage and a reference voltage;
• an amplifier connected to provide a ramp voltage substantially proportional to said first current;
• a comparator coupled to provide said pulse width modulation signal in response to the difference between said ramp voltage and said error voltage;
• a differential amplifier arranged to provide a ripple current to said amplifier output in response to the difference between said error voltage and a clamp voltage;
• and
• a current comparator arranged to provide a skip signal to turn off said first and second currents in response to a selected threshold of said ripple current;
• said ripple current substantially clamping said error voltage to said clamp voltage.

A method to provide an output voltage, comprising the steps of:

• arranging a switching voltage converter with an inductor to switch through said inductor first and second currents with duty cycles controlled by an error voltage to thereby maintain said output voltage;
• coupling a transconductance amplifier having an amplifier output to provide said error voltage in response to said output voltage and a reference voltage;
• providing a ripple current to said amplifier output in response to the difference between said error voltage and a clamp voltage;
• and
• generating a skip signal to turn off said first and second currents in response to a selected threshold of said ripple current;
• said ripple current substantially clamping said error voltage to said clamp voltage.