Average current controlled switching regulator utilizing digital control techniques

A current controlled switching type voltage regulator including input means;

• output means, switching means coupling said input and output means;
• clock means for periodically initiating conduction in said switching means;
• current sensing means coupled to sense a current proportional to current flow through said switching means;
• a current-to-digital transducer coupled to said current sensing means and generating a signal frequency proportional to a current magnitude sensed therein;
• the current-to-digital transducer comprising:
• an operational amplifier having positive and negative input leads shunted across a sensing resistor included in said current sensing means and located in a path of a current being sensed and a feedback resistor equal in magnitude to the positive and negative input resistances to said operational amplifier;
• and
• a voltage controlled oscillator responsive to an output voltage of the operational amplifier;
• said current-to-digital transducer constructed to operate with a residual signal frequency output below a predetermined threshold current level;
• first counting means responsive to an output of said current-to-digital transducer means operative to derive a number proportional to an average of the current flow through said switching device;
• a current reference count register;
• means for modifying a reference count in said current reference count register, means for comparing a count in said first counting means with a count output of said means for modifying a reference count;
• a voltage-to-digital transducer responsive to a voltage at said output means, second counting means coupled to respond to said voltage-to-digital transducer;
• and
• a voltage reference count register, difference means for generating an error count in response to comparing a count of said second counter accumulated during a complete period of said clock means with a count output of said voltage reference count register, said error count being coupled to said means for modifying a count in said current reference count register whereby a count output of said first counter is compared with a count output of said means for modifying a reference count in order to control a conduction interval of said switching means in order to regulate a voltage output by controlling current through said switching means.