Integrated circuit for controlling power converter by frequency modulation and pulse width modulation

An integrated circuit comprising:

• voltage-controlled oscillator means for providing a variable frequency VCO signal in response to an external input signal;
• a first flip-flop having an input and a pair of complementary outputs, said flip-flop input being connected to the output of said voltage-controlled oscillator means;
• a first two-input AND gate for providing a turn-on pulse and having one input connected to one of said flip-flop outputs;
• a second two-input AND gate for providing a turn-on pulse and having one input connected to the other of said flip-flop outputs;
• amplifier means for receiving an input signal and providing an output signal,
• a first comparator having one input coupled to the output of said amplifier means and having its other input coupled to the output of said voltage-controlled oscillator means, the output of said first comparator being coupled to the remaining inputs of said first and second AND gates;
• a third AND gate having an input responsive to an enable signal;
• a fourth AND gate having an input responsive to said enable signal;
• a first dead-time circuit coupling the output of said first AND gate to an input of said third AND gate, said first dead-time circuit delaying the beginning of each turn-on pulse from said first AND gate by a first predetermined dead-time;
• a second dead-time circuit coupling the output of said second AND gate to an input of said fourth AND gate, said second dead-time circuit delaying the beginning of each turn-on pulse from said second AND gate by a second predetermined dead-time;
• and
• a driver circuit connected to the outputs of said third and fourth AND gates, said driver circuit having outputs adapted to drive a pair of series-connected converter switches, said driver circuit adapted to be coupled to an external capacitor for providing a voltage sufficient to drive the upper one of said converter switches.