Current limit scheme for dc-dc converters

An electronic system that provides an output signal in response to an input signal, comprising:

• a load circuit wherein said output signal is measured across said load circuit;
• a DC-DC converter circuit, comprising:
• a first power device that can operate in an on-state and an off-state;
• a second power device that can operate in an on-state and an off-state;
• an inductor connected serially between said first and second side power devices and said load circuit;
• and
• a capacitor connected in parallel with said load circuit;
• a current sensor connected to sense current through said second power device;
• a tracking element connected to increment a count value for each cycle in which a current through said second power device exceeds a current limit value and decrement said count value for every cycle in which said current does not exceed said current limit value;
• and
• a modulator connected to modulate the time that said first power device is in the on-state during a given cycle based on information from said tracking element;
• wherein the time that said first power device is in the on-state is inversely related to said count value.

A DC-DC converter, comprising:

• a DC-DC converter circuit comprising a first power device switchable between and on-state and an off-state and a second power device switchable between an on-state and an off-state;
• wherein the time that said first power device operates in the on-state during a given cycle is reduced in a subsequent cycle if a current through said second power device exceeds a current limit value during said given cycle;
• and
• wherein said first power device is switched to the off-state for a period of time when a count value at least partially based on the number of previous cycles in which said current limit value is exceeded reaches a maximum value.