Power supply device, control circuit, electronic device and control method for power supply
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 power supply device, comprising:
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 that adds a slope voltage to a reference voltage;
a control unit that 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; and
a slope adjustment circuit that differentiates a current flowing in the coil and adjusts a slope amount of the slope based on a differentiation result of the current.
2. The power supply device according to claim 1 , wherein the slope adjustment circuit includes:
a first amplifier that converts the current flowing in the coil into a voltage;
a differentiating circuit that differentiates an output voltage of the first amplifier;
a second amplifier that amplifies an output of the differentiating circuit; and
a hold circuit that holds an output voltage of the second amplifier.
3. The power supply device according to claim 2 , wherein the slope adjustment circuit includes:
a third amplifier that amplifies an output voltage of the hold circuit; and
a low-pass filter that reduces noise of an output voltage of the third amplifier.
4. The power supply device according to claim 2 , wherein the slope adjustment circuit includes a current conversion circuit that converts an output voltage of the hold circuit into a current.
5. The power supply device according to claim 3 , wherein the slope adjustment circuit includes a current conversion circuit that converts an output voltage of the low-pass filter into a current.
6. The power supply device according to claim 1 , wherein the slope adjustment circuit adjusts the slope amount of the slope based on the differentiation result of the current flowing in the coil during a period in which the switch circuit is on.
7. A control circuit for a power supply, comprising:
a voltage adding circuit that adds a slope voltage to a reference voltage;
a control unit that compares a feedback voltage corresponding to an output voltage of the power supply and the reference voltage and switches a switch circuit, to which an input voltage of the power supply is supplied, at a timing corresponding to a comparison result of the feedback voltage and the reference voltage; and
a slope adjustment circuit that differentiates a current flowing in a coil coupled between the switch circuit and an output terminal from which the output voltage of the power supply is outputted and adjusts a slope amount of the slope based on a differentiation result of the current.
8. An electronic device comprising:
a power supply including a control circuit; and
an internal circuit to which an output voltage of the power supply is supplied, wherein the control circuit includes:
a voltage adding circuit that adds a slope voltage to a reference voltage;
a control unit that compares a feedback voltage corresponding to the output voltage of the power supply and the reference voltage and switches a switch circuit, to which an input voltage of the power supply is supplied, at a timing corresponding to a comparison result of the feedback voltage and the reference voltage; and
a slope adjustment circuit that differentiates a current flowing in a coil coupled between the switch circuit and an output terminal from which the output voltage of the power supply is outputted and adjusts a slope amount of the slope based on a differentiation result of the current.
9. A method for controlling a power supply outputting an output voltage, the comprising:
adding a slope voltage to a reference voltage;
comparing a feedback voltage corresponding to the output voltage of the power supply and the reference voltage;
switching a switch circuit, to which an input voltage of the power supply is supplied, at a timing corresponding to a result of the comparing;
differentiating a current flowing in a coil coupled between the switch circuit and an output terminal from which the output voltage of the power supply is outputted; and
adjusting a slope amount of the slope based on a differentiation result of the current.