Power supply circuit, power supply control circuit, and power supply control method
View Patent ↗A DC-DC converter and first and second bypass switch circuits are provided in parallel between an input pin and first and second output pins and operate in accordance with a combination of the voltage value of the input pin and the voltage value required for the first output pin. A start control circuit causes the DC-DC converter to operate unconditionally in a step-down mode during the period from when the DC-DC converter is started until the output voltage of the DC-DC converter becomes equal to the voltage of the input pin. An output slope control circuit synchronizes rising slopes of the output voltages of the first and second bypass switch circuits with a rising slope of the output voltage of the DC-DC converter.
1. A power supply circuit comprising:
an input pin receiving a voltage of either a first predetermined value or a second predetermined value smaller than the first predetermined value;
a first output pin for which an output of a voltage of either the first or second predetermined value is required;
a second output pin for which an output of a voltage of the second predetermined value is required;
a DC-DC converter generating an output voltage from the voltage of the input pin in either a step-down mode or a boost mode and outputting the output voltage to at least one of the first and second output pins in accordance with a combination of the voltage value of the input pin and the voltage value required for the first output pin;
a first bypass switch circuit turning on to output the voltage of the input pin to the first output pin when the voltage is not output to the first output pin from the DC-DC converter;
a second bypass switch circuit turning on to output the voltage of the input pin to the second output pin when the voltage is not output to the second output pin from the DC-DC converter;
a start control circuit causing the DC-DC converter to operate in the step-down mode irrespective of the combination of the voltage value of the input pin and the voltage value required for the first output pin during the period from when the DC-DC converter is started until the output voltage of the DC-DC converter becomes equal to the voltage of the input pin; and
an output slope control circuit synchronizing a rising slope of the output voltage of the first bypass switch circuit with a rising slope of the output voltage of the DC-DC converter when the first bypass switch circuit turns on and synchronizes a rising slope of the output voltage of the second bypass switch circuit with a rising slope of the output voltage of the DC-DC converter when the second bypass switch circuit turns on.
2. The power supply circuit according to claim 1 , wherein
the DC-DC converter:
generates an output voltage of the second predetermined value from the voltage of the input pin in the step-down mode and outputs the output voltage to the second output pin when the voltage value of the input pin is the first predetermined value and the voltage value required for the first output pin is the first predetermined value;
generates an output voltage of the second predetermined value from the voltage of the input pin in the step-down mode and outputs the output voltage to the first and second output pins when the voltage value of the input pin is the first predetermined value and the voltage value required for the first output pin is the second predetermined value;
generates an output voltage of the first predetermined value from the voltage of the input pin in the boost mode and outputs the output voltage to the first output pin when the voltage value of the input pin is the second predetermined value and the voltage value required for the first output pin is the first predetermined value; and
generates an output voltage of the second predetermined value from the voltage of the input pin in the boost mode and outputs the output voltage to the first and second output pins when the voltage value of the input pin is the second predetermined value and the voltage value required for the first output pin is the second predetermined value.
3. The power supply circuit according to claim 1 , wherein
the output slope control circuit includes:
a first on-state resistance control circuit that detects a voltage difference between a voltage that follows the voltage of the first output pin and the voltage of the second output pin and controls an on-state resistance of the first bypass switch circuit in accordance with the detection result when the first bypass switch circuit turns on; and
a second on-state resistance control circuit that detects a voltage difference between the voltage of the second output pin and a voltage that follows the voltage of the first output pin and controls an on-state resistance of the second bypass switch circuit in accordance with the detection result when the second bypass switch circuit turns on.
4. The power supply circuit according to claim 1 , wherein:
the power supply circuit is mounted on a memory card that has a non-volatile memory and a memory control circuit that controls the non-volatile memory;
the voltage of the first output pin is used as a power supply voltage of the non-volatile memory; and
the voltage of the second output pin is used as a power supply voltage of the memory control circuit.
5. The power supply circuit according to claim 1 , wherein
the power supply circuit is constituted using a semiconductor device.
6. A power supply control circuit used in a power supply circuit comprising:
an input pin receiving a voltage of either a first predetermined value or a second predetermined value smaller than the first predetermined value;
a first output pin for which an output of a voltage of either the first or second predetermined value is required;
a second output pin for which an output of a voltage of the second predetermined value is required;
a DC-DC converter generating an output voltage from the voltage of the input pin in either a step-down mode or a boost mode and outputs the output voltage to at least one of the first and second output pins in accordance with a combination of the voltage value of the input pin and the voltage value required for the first output pin;
a first bypass switch circuit turning on to output the voltage of the input pin to the first output pin when the voltage is not output to the first output pin from the DC-DC converter; and
a second bypass switch circuit turning on to output the voltage of the input pin to the second output pin when the voltage is not output to the second output pin from the DC-DC converter, the power supply control circuit comprising;
a start control circuit causing the DC-DC converter to operate in the step-down mode irrespective of the combination of the voltage value of the input pin and the voltage value required for the first output pin during the period from when the DC-DC converter is started until the output voltage of the DC-DC converter becomes equal to the voltage of the input pin; and
an output slope control circuit synchronizing a rising slope of the output voltage of the first bypass switch circuit with a rising slope of the output voltage of the DC-DC converter when the first bypass switch circuit turns on and synchronizes a rising slope of the output voltage of the second bypass switch circuit with a rising slope of the output voltage of the DC-DC converter when the second bypass switch circuit turns on.
7. The power supply control circuit according to claim 6 , wherein
the output slope control circuit includes:
a first on-state resistance control circuit that detects a voltage difference between a voltage that follows the voltage of the first output pin and the voltage of the second output pin and controls an on-state resistance of the first bypass switch circuit in accordance with the detection result when the first bypass switch circuit turns on; and
a second on-state resistance control circuit that detects a voltage difference between the voltage of the second output pin and a voltage that follows the voltage of the first output pin and controls an on-state resistance of the second bypass switch circuit in accordance with the detection result when the second bypass switch circuit turns on.
8. The power supply control circuit according to claim 6 , wherein:
the power supply circuit is mounted on a memory card that has a non-volatile memory and a memory control circuit that controls the non-volatile memory;
the voltage of the first output pin is used as a power supply voltage of the non-volatile memory; and
the voltage of the second output pin is used as a power supply voltage of the memory control circuit.
9. A power supply control method controlling a power supply circuit comprising:
an input pin receiving a voltage of either a first predetermined value or a second predetermined value smaller than the first predetermined value;
a first output pin for which an output of a voltage of either the first or second predetermined value is required;
a second output pin for which an output of a voltage of the second predetermined value is required;
a DC-DC converter generating an output voltage from the voltage of the input pin in either a step-down mode or a boost mode and outputs the output voltage to at least one of the first and second output pins in accordance with a combination of the voltage value of the input pin and the voltage value required for the first output pin;
a first bypass switch circuit turning on to output the voltage of the input pin to the first output pin when the voltage is not output to the first output pin from the DC-DC converter; and
a second bypass switch circuit that turns on to output the voltage of the input pin to the second output pin when the voltage is not output to the second output pin from the DC-DC converter, the method comprising:
a start control process causing the DC-DC converter to operate in the step-down mode irrespective of the combination of the voltage value of the input pin and the voltage value required for the first output pin during the period from when the DC-DC converter is started until the output voltage of the DC-DC converter becomes equal to the voltage of the input pin; and
an output slope control process synchronizing a rising slope of the output voltage of the first bypass switch circuit with a rising slope of the output voltage of the DC-DC converter when the first bypass switch circuit turns on and synchronizes a rising slope of the output voltage of the second bypass switch circuit with a rising slope of the output voltage of the DC-DC converter when the second bypass switch circuit turns on.
10. The power supply control method according to claim 9 , wherein
the output slope control process includes:
a first on-state resistance control process that detects a voltage difference between a voltage that follows the voltage of the first output pin and the voltage of the second output pin and controls an on-state resistance of the first bypass switch circuit in accordance with the detection result when the first bypass switch circuit turns on; and
a second on-state resistance control process that detects a voltage difference between the voltage of the second output pin and a voltage that follows the voltage of the first output pin and controls an on-state resistance of the second bypass switch circuit in accordance with the detection result when the second bypass switch circuit turns on.
11. The power supply control method according to claim 9 , wherein
the power supply circuit is mounted on a memory card that has a non-volatile memory and a memory control circuit that controls the non-volatile memory;
the voltage of the first output pin is used as a power supply voltage of the non-volatile memory; and
the voltage of the second output pin is used as a power supply voltage of the memory control circuit.