Multi-phase DC-DC converter and control circuit for multi-phase DC-DC converter
View Patent ↗A self-excited multi-phase DC—DC converter having satisfactory responsiveness when its load suddenly changes. A control unit of the converter compares output currents of first and second converter units. Based on the comparison result, the control unit generates control signals to operate a converter unit through which a smaller output current flows. For example, when an output voltage of the converter decreases due to a sudden change in the load while the first converter unit is operating to supply current, the second converter unit through which a smaller output current flows is operated to increase the output voltage.
1. A multi-phase DC—DC converter comprising:
an output terminal;
a plurality of converter units, each receiving an input voltage and generating an output voltage for said output terminal; and
a control unit connected to the plurality of converter units, the control unit including:
a first voltage comparator for comparing the output voltage with a first reference voltage to generate a first voltage comparison signal indicating the comparison result;
a current comparison circuit for comparing a plurality of output currents that are in accordance with the output voltages of the converter units to generate a plurality of current comparison signals respectively corresponding to the converter units; and
a signal generation circuit, connected to the first voltage comparator and the current comparison circuit, for generating a plurality of control signals for respectively controlling the converter units so that a converter unit through which a smaller output current flows is operated in accordance with the current comparison signals generated by the current comparison circuit when the first voltage comparison signal indicates that the output voltage is lower than the first reference voltage.
2. The multi-phase DC—DC converter according to claim 1 , wherein each of the converter units includes a current detection resistor, and the current comparison circuit includes:
a plurality of voltage amplifiers respectively connected to the converter units, each voltage amplifier amplifying a voltage difference between two terminals of the current detection resistor included in the corresponding converter unit to generate an amplified voltage; and
a comparator, connected to the plurality of voltage amplifiers, for comparing a plurality of voltages to generate the current comparison signals.
3. The multi-phase DC—DC converter according to claim 1 , wherein the signal generation circuit includes:
a plurality of AND circuits connected to the first voltage comparator and the current comparison circuit, each AND circuit receiving the current comparison signal for the corresponding converter unit and the first voltage comparison signal to generate a logical AND output signal; and
a plurality of one-shot flip-flop circuits respectively connected to the AND circuits, each of the one-shot flip-flop circuits generating a control signal for controlling the corresponding converter unit in response to the logical AND output signal of the corresponding AND circuit.
4. The multi-phase DC—DC converter according to claim 1 , wherein:
the control unit includes a second voltage comparator for comparing the output voltage with a second reference voltage that is lower than the first reference voltage to generate a second voltage comparison signal; and
when the second voltage comparison signal indicates that the output voltage at the output terminal is lower than the second reference voltage, the signal generation circuit invalidates the current comparison signals of the current comparison circuit and generates a plurality of control signals to synchronously operate the converter units.
5. The multi-phase DC—DC converter according to claim 4 , wherein the signal generation circuit includes:
a plurality of OR circuits connected to the current comparison circuit and the second voltage comparator, each OR circuit receiving the current comparison signal of the corresponding converter unit and the second voltage comparison signal to generate a logical OR output signal;
a plurality of AND circuits connected to the first voltage comparator and respectively to the OR circuits, each AND circuit receiving the logical OR output signal of the corresponding OR circuit and the first voltage comparison signal to generate a logical AND output signal; and
a plurality of one-shot flip-flop circuits respectively connected to the AND circuits, each one-shot flip-flop circuit generating the control signal for controlling the corresponding converter unit in response to the logical AND output signal of the corresponding AND circuit.
6. The multi-phase DC—DC converter according to claim 1 , wherein:
the control unit includes a degeneracy operation control circuit for adding the output currents of the converter units to obtain a total output current and generating a plurality of degeneracy control signals for selectively inactivating the converter units based on the total output current; and
the current comparison circuit generates the current comparison signals for selectively inactivating the plurality of converter units in accordance with the degeneracy control signals.
7. The multi-phase DC—DC converter according to claim 6 , wherein the degeneracy operation control circuit includes:
an adder for adding the output currents of the converter units to generate a sum signal; and
a signal generation circuit, connected to the adder, for comparing the sum signal with a predetermined threshold value and generating the degeneracy control signals, each of which indicates a current greater than a current flowing through the corresponding converter unit based on the comparison result;
wherein the current comparison circuit compares the current flowing through each of the converter units with a current indicated by the corresponding degeneracy control signal to generate the current comparison signals so that the converter unit through which a greater output current flows is inactivated.
8. The multi-phase DC—DC converter according to claim 6 , wherein the control unit includes a second voltage comparator for comparing the output voltage with a second reference voltage that is lower than the first reference voltage to generate a second voltage comparison signal; and
when the second voltage comparison signal indicates that the output voltage is lower than the second reference voltage, the signal generation circuit invalidates the current comparison signals of the current comparison circuit and the degeneracy control signals and generates a plurality of control signals to synchronously operate the converter units.
9. The multi-phase DC—DC converter according to claim 6 , wherein the control unit includes a second voltage comparator for comparing the output voltage with a second reference voltage that is lower than the first reference voltage to generate a second voltage comparison signal; and
when the second voltage comparison signal indicates that the output voltage at the output terminal is lower than the second reference voltage, the signal generation circuit invalidates the current comparison signals of the current comparison circuit and generates a plurality of control signals to synchronously operate operable converter units selected by the degeneracy control signals.
10. The multi-phase DC—DC converter according to claim 9 , wherein the signal generation circuit includes:
a plurality of OR circuits connected to the current comparison circuit and the second voltage comparator, each OR circuit receiving the current comparison signal of the corresponding converter unit and the second voltage comparison signal to generate a logical OR output signal;
a plurality of AND circuits connected to the first voltage comparator and the degeneracy operation control circuit and respectively to the OR circuits, each AND circuit receiving the first voltage comparison signal, the corresponding degeneracy control signal, and the corresponding logical OR output signal to generate a logical AND output signal; and
a plurality of one-shot flip-flop circuits respectively connected to the plurality of AND circuits, each one-shot flip-flop circuit generating the control signal for controlling the corresponding converter unit in response to the logical AND output signal generated by the corresponding AND circuit.
11. A control circuit for controlling a multi-phase DC—DC converter that includes an output terminal and a plurality of converter units, each receiving an input voltage and generating an output voltage for the output terminal of the DC—DC converter, the circuit comprising:
a first voltage comparator for comparing the output voltage with a first reference voltage to generate a first voltage comparison signal indicating the comparison result;
a current comparison circuit for comparing a plurality of output currents that are in accordance with the output voltages generated by the converter units to generate a plurality of current comparison signals respectively corresponding to the converter units; and
a signal generation circuit, connected to the first voltage comparator and the current comparison circuit, for generating a plurality of control signals for respectively controlling the converter units so that a converter unit through which a smaller output current flows is operated in accordance with the current comparison signals generated by the current comparison circuit when the first voltage comparison signal indicates that the output voltage is lower than the first reference voltage.
12. The control circuit according to claim 11 , further comprising:
a second voltage comparator for comparing the output voltage with a second reference voltage that is lower than the first reference voltage to generate a second voltage comparison signal;
wherein when the second voltage comparison signal indicates that the output voltage is lower than the second reference voltage, the signal generation circuit invalidates the current comparison signals of the current comparison circuit and generates a plurality of control signals to synchronously operate the converter units.
13. The control circuit according to claim 11 , further comprising:
a degeneracy operation control circuit for adding the output currents of the converter units to obtain a total output current and generating a plurality of degeneracy control signals for selectively inactivating the converter units based on the total output current;
wherein the current comparison circuit generates the current comparison signals for selectively inactivating the converter units in accordance with the degeneracy control signals.
14. The control circuit according to claim 13 , further comprising:
a second voltage comparator for comparing the output voltage with a second reference voltage that is lower than the first reference voltage to generate a second voltage comparison signal;
wherein when the second voltage comparison signal indicates that the output voltage is lower than the second reference voltage, the signal generation circuit invalidates the current comparison signals of the current comparison circuit and the degeneracy control signals and generates the control signals to synchronously operate the converter units.
15. The control circuit according to claim 13 , further comprising:
a second voltage comparator for comparing the output voltage with a second reference voltage that is lower than the first reference voltage to generate a second voltage comparison signal;
wherein when the second voltage comparison signal indicates that the output voltage is lower than the second reference voltage, the signal generation circuit invalidates the current comparison signals generated by the current comparison circuit and generates the control signals to synchronously operate operable converter units selected by the degeneracy control signals.
16. A method for controlling a multi-phase DC—DC converter including an output terminal and a plurality of converter units, each receiving an input voltage and generating an output voltage for the output terminal of the DC—DC converter, the method comprising:
comparing the output voltage with a first reference voltage to generate a first voltage comparison signal indicating the comparison result;
comparing a plurality of output currents that are in accordance with the output voltages generated by the converter units to generate a plurality of current comparison signals respectively corresponding to the converter units; and
generating a plurality of control signals for respectively controlling the converter units so that a converter unit through which a smaller output current flows is operated in accordance with the current comparison signals when the first voltage comparison signal indicates that the output voltage is lower than the first reference voltage.
17. The method according to claim 16 , further comprising:
comparing the output voltage with a second reference voltage that is lower than the first reference voltage to generate a second voltage comparison signal;
wherein said generating a plurality of control signals includes invalidating the plurality of current comparison signals and generating the control signals to synchronously operate the converter units when the second voltage comparison signal indicates that the output voltage at the output terminal is lower than the second reference voltage.
18. The method according to claim 16 , further comprising:
adding the output currents of the converter units to obtain a total output current and generate a plurality of degeneracy control signals for selectively inactivating the converter units based on the total output current;
wherein said generating a plurality of current comparison signals includes generating the current comparison signals to selectively inactivate the plurality of converter units in accordance with the plurality of degeneracy control signals.
19. The method according to claim 18 , further comprising:
comparing the output voltage with a second reference voltage that is lower than the first reference voltage to generate a second voltage comparison signal;
wherein said generating a plurality of control signals includes invalidating the current comparison signals and the degeneracy control signals and generating the control signals to synchronously operate the converter units when the second voltage comparison signal indicates that the output voltage at the output terminal is lower than the second reference voltage.
20. The method according to claim 18 , further comprising:
comparing the output voltage with a second reference voltage that is lower than the first reference voltage to generate a second voltage comparison signal;
wherein said generating a plurality of control signals includes invalidating the current comparison signals and generating the control signals to synchronously operate operable converter units that are selected by the degeneracy control signals when the second voltage comparison signal indicates that the output voltage at the output terminal is lower than the second reference voltage.