Power supply device, control circuit, electronic device and control method for power supply
View Patent ↗A power supply device that includes a switch circuit to which an input voltage is supplied, a coil coupled between the switch circuit and an output terminal from which an output voltage is outputted. A voltage adding circuit adds a slope voltage to a reference voltage. A control unit compares a feedback voltage corresponding to the output voltage and the reference voltage and switches the switch circuit at a timing corresponding to a comparison result of the feedback voltage and the reference voltage. A slope adjustment circuit differentiates a current flowing in the coil and adjusts a slope amount of the slope based on a differentiation result of the current.
1. A method for controlling crossover frequency in a power supply, comprising:
supplying an input voltage to a switch circuit;
feeding back an inductance value of a coil coupled between the switch circuit and an output terminal from which an output voltage is outputted;
adjusting a slope voltage based on the inductance value of the coil; and
adding the slope voltage to a reference voltage.
2. The method of claim 1 , further comprising:
maintaining the crossover frequency substantially constant regardless of variation in the input voltage.
3. The method of claim 1 , further comprising:
maintaining the crossover frequency substantially constant regardless of variation in the inductance value of the coil.
4. The method of claim 1 , further comprising:
suppressing a reduction in phase margin for decreasing inductance value of the coil with increasing current in the coil.
5. The method of claim 1 , further comprising:
suppressing a reduction in phase margin for variation in the input voltage.
6. The method of claim 1 , wherein:
an inductance value of the coil changes due to variation in bias current flowing in the coil.
7. The method of claim 1 , further comprising:
detecting slope of the current in the coil through use of a detector circuit.
8. The method of claim 7 , wherein the detector circuit is configured to determine an inductance value of the coil from the slope of the current in the coil.
9. The method of claim 8 , wherein the detector circuit is further configured to provide a control signal to a control unit based on the value of the detected slope of the current in the coil.
10. The method of claim 9 , wherein the control unit is configured to generate current from a current source controlled by the control signal.
11. The method of claim 10 , further comprising:
generating the slope voltage proportional to the current produced by the control unit.
12. An apparatus for controlling the crossover frequency in a power supply, comprising:
an input voltage to a switch circuit;
a coil coupled between the switch circuit and an output terminal, an output voltage being output from the output terminal;
a detector circuit configured to determine the slope of the current in the coil;
a control unit configured to adjust a current source to produce a current proportional to the detected slope of the current in the coil;
a voltage adding circuit configured to add a slope voltage to a reference voltage; and
a slope adjustment circuit configured to differentiate the current flowing in the coil and adjust the amount of the slope voltage based on a differentiation result of the current in the coil.
13. The apparatus of claim 12 , wherein the apparatus maintains the crossover frequency substantially constant regardless of variation in the input voltage.
14. The apparatus of claim 12 , wherein the apparatus maintains the crossover frequency substantially constant regardless of variation in the inductance value of the coil.
15. The apparatus of claim 12 , wherein the apparatus suppresses a reduction in phase margin for decreasing inductance value of the coil with increasing current in the coil.
16. The apparatus of claim 12 , wherein the apparatus suppresses a reduction in phase margin for variation in the input voltage.
17. The apparatus of claim 12 , wherein an inductance value of the coil changes due to variation in a bias current flowing in the coil.