Resonant DC-DC converter with average half cycle control
Resonant DC-DC converter control circuitry includes a feedback input, a differential integrator, a resonant voltage input, a first comparator, and a second comparator. The differential integrator includes a first input, a second input, a first output, and a second output. The first input is coupled to the feedback input. The second input is coupled to a ground terminal. The first comparator includes a first input coupled to the resonant voltage input, and a second input coupled to the first output of the differential integrator. The second comparator includes a first input coupled to the resonant voltage input, and a second input coupled to the second output of the differential integrator.
1. A resonant DC-DC converter control circuitry, comprising:
a feedback input;
a differential integrator including:
a first input coupled to the feedback input;
a second input coupled to a ground terminal;
a first output; and
a second output;
a resonant voltage input;
a first comparator including:
an output;
a first input coupled to the resonant voltage input; and
a second input coupled to the first output of the differential integrator;
a second comparator including:
an output;
a first input coupled to the resonant voltage input; and
a second input coupled to the second output of the differential integrator;
a first flip-flop including an input coupled to the output of the first comparator, and an output;
a second flip-flop including an input coupled to the output of the second comparator, and an output; and
a monostable multivibrator including an input coupled to the output of the first flip-flop and the output of the second flip-flop.
2. The resonant DC-DC converter control circuitry of claim 1 , wherein:
the monostable multivibrator includes an output; and
the differential integrator includes:
a first switch coupled between the first input of the differential integrator and the first output of the differential integrator, the first switch having a control terminal coupled to the output of the monostable multivibrator; and
a second switch coupled between the second input of the differential integrator and the second output of the differential integrator, the second switch having a control terminal coupled to the output of the monostable multivibrator.
3. The resonant DC-DC converter control circuitry of claim 1 , wherein the differential integrator includes:
a first capacitor coupled between the first input of the differential integrator and the first output of the differential integrator; and
a second capacitor coupled between the second input of the differential integrator and the second output of the differential integrator.
4. The resonant DC-DC converter control circuitry of claim 1 , further comprising:
an integrator circuit including:
an input coupled to the resonant voltage input; and
an output coupled to the first input of the first comparator and the first input of the second comparator;
a resistor coupled to the input of the integrator circuit;
a first switch coupled between the resistor and a power terminal; and
a second switch coupled between the resistor and a ground terminal.
5. The resonant DC-DC converter control circuitry of claim 4 , wherein:
the resistor is a first resistor; and
the resonant DC-DC converter control circuitry includes:
a second resistor coupled between the resonant voltage input and the input of the integrator circuit; and
a third resistor coupled between the power terminal and the input of the integrator circuit.
6. The resonant DC-DC converter control circuitry of claim 5 , wherein:
the second resistor and the third resistor are variable resistors; and
resonant DC-DC converter control circuitry includes:
an analog-to-digital converter including:
an input coupled to the resonant voltage input; and
an output coupled to the second resistor and the third resistor.
7. A resonant DC-DC converter control circuitry, comprising:
a differential integrator configured to:
generate a first threshold ramp based on a feedback signal received from an output of a resonant DC-DC converter;
generate a second threshold ramp based on the feedback signal;
a first comparator coupled to the differential integrator, and configured to compare the first threshold ramp to a resonant voltage generated in the resonant DC-DC converter;
a second comparator coupled to the differential integrator, and configured to compare the second threshold ramp to the resonant voltage;
a first flip-flop coupled to the first comparator, and configured to generate a first power transistor control signal based on an output signal of the first comparator;
a second flip-flop coupled to the second comparator, and configured to generate a second power transistor control signal based on an output signal of the second comparator; and
a monostable multivibrator coupled to the first flip-flop and the second flip-flop, and configured to generate a pulse responsive to the first power transistor control signal or the second power transistor control signal.
8. The resonant DC-DC converter control circuitry of claim 7 , wherein the differential integrator is configured to reset the first threshold ramp and the second threshold ramp responsive to a pulse generated by the monostable multivibrator.
9. The resonant DC-DC converter control circuitry of claim 7 , further comprising:
an integrator circuit coupled to the first comparator and the second comparator, and configured to integrate the resonant voltage.
10. The resonant DC-DC converter control circuitry of claim 9 , further comprising:
a ramp generation circuit coupled to the integrator circuit, and configured to switch source and sink current through a resistor to the integrator circuit.
11. The resonant DC-DC converter control circuitry of claim 9 , further comprising a resistor network coupled to the integrator circuit, and configured to scale the resonant voltage for input to the integrator circuit.
12. The resonant DC-DC converter control circuitry of claim 11 , wherein:
a resistance of the resistor network is variable; and
the resonant DC-DC converter control circuitry includes an analog-to-digital converter coupled to the resistor network, and configured to set the resistance of the resistor network based on an input voltage switched by the resonant DC-DC converter.
13. A resonant DC-DC converter control circuitry, comprising:
a first flip-flop configured to generate a first power transistor control signal; and
a second flip-flop configured to generate a second power transistor control signal;
a time-to-voltage converter coupled to the first flip-flop and the second flip-flop, and configured to generate a time voltage proportional to a half cycle of the first power transistor control signal or the second power transistor control signal;
a multiplier coupled to the time-to-voltage converter, and configured to multiply the time voltage with a feedback signal received from an output of a resonant DC-DC converter; and
a differential amplifier coupled to the multiplier, and configured to generate a first threshold voltage and a second threshold voltage based on an output signal of the multiplier.
14. The resonant DC-DC converter control circuitry of claim 13 , further comprising:
a first comparator coupled to the differential amplifier and the first flip-flop, and configured to compare the first threshold voltage to a resonant voltage generated in the resonant DC-DC converter; and
a second comparator coupled to the differential amplifier and the second flip-flop, and configured to compare the second threshold voltage to the resonant voltage.
15. The resonant DC-DC converter control circuitry of claim 14 , further comprising:
an integrator circuit coupled to the first comparator and the second comparator, and configured to integrate the resonant voltage.
16. The resonant DC-DC converter control circuitry of claim 15 , further comprising:
a ramp generation circuit coupled to the integrator circuit, and configured to switch source and sink current through a resistor to the integrator circuit.
17. The resonant DC-DC converter control circuitry of claim 15 , further comprising:
a resistor network coupled to the integrator circuit, and configured to scale the resonant voltage for input to the integrator circuit.
18. The resonant DC-DC converter control circuitry of claim 17 , wherein:
a resistance of the resistor network is variable; and
the resonant DC-DC converter control circuitry includes an analog-to-digital converter coupled to the resistor network, and configured to set the resistance of the resistor network based on an input voltage switched by the resonant DC-DC converter.