Power supply unit and electronic timepiece
A power supply unit has a first power supply circuit that supplies a voltage to a load driving unit and a second power supply circuit that supplies a voltage to circuits other than the load driving unit. A first switching unit connects any one of a power supply that supplies a power supply voltage and a voltage step-down circuit that supplies a step-down voltage of the power supply voltage to the first power supply circuit. A second switching unit connects any one of the power supply and the voltage step-down circuit to the second power supply circuit. A control unit controls the connection by the first switching unit and the connection by the second switching unit to switch the voltage supplied to the first power supply circuit and the voltage supplied to the second power supply circuit in accordance with properties of the load driving unit.
1. A power supply unit comprising:
a first power supply circuit that supplies a voltage to a load driving unit that drives a load unit;
a second power supply circuit that supplies a voltage to circuits other than the load driving unit;
a first switching unit that connects any one of a power supply that supplies a power supply voltage and a voltage step-down circuit that supplies a step-down voltage of the power supply voltage to the first power supply circuit;
a second switching unit that connects any one of the power supply that supplies the power supply voltage and the voltage step-down circuit that supplies the step-down voltage of the power supply voltage to the second power supply circuit, the second switching unit being disposed in parallel to the first switching unit; and
a control unit that controls the connection by the first switching unit and the connection by the second switching unit to switch the voltage supplied to the first power supply circuit and the voltage supplied to the second power supply circuit in accordance with properties of the load driving unit.
2. The power supply unit according to claim 1 , further comprising:
a battery voltage detection unit that detects the power supply voltage,
wherein the control unit performs switching based on the detected power supply voltage.
3. The power supply unit according to claim 2 , wherein when the detected power supply voltage is lower than a voltage determined based on a voltage necessary for driving the load unit using the step-down voltage supplied from the voltage step-down circuit, the control unit connects the first switching unit to the power supply.
4. The power supply unit according to claim 2 , wherein when the detected power supply voltage is lower than a voltage determined based on a voltage necessary for driving circuits other than the load driving unit using the step-down voltage supplied from the voltage step-down circuit, the control unit connects the second switching unit to the power supply.
5. The power supply unit according to claim 3 , wherein when the detected power supply voltage is lower than a voltage determined based on a voltage necessary for driving circuits other than the load driving unit using the step-down voltage supplied from the voltage step-down circuit, the control unit connects the second switching unit to the power supply.
6. The power supply unit according to claim 2 , wherein when the detected power supply voltage is not less than a voltage determined based on a voltage necessary for driving the load unit using the power supply voltage supplied from the power supply, the control unit drives the load unit.
7. The power supply unit according to claim 3 , wherein when the detected power supply voltage is not less than a voltage determined based on a voltage necessary for driving the load unit using the power supply voltage supplied from the power supply, the control unit drives the load unit.
8. The power supply unit according to claim 4 , wherein when the detected power supply voltage is not less than a voltage determined based on a voltage necessary for driving the load unit using the power supply voltage supplied from the power supply, the control unit drives the load unit.
9. The power supply unit according to claim 5 , wherein when the detected power supply voltage is not less than a voltage determined based on a voltage necessary for driving the load unit using the power supply voltage supplied from the power supply, the control unit drives the load unit.
10. The power supply unit according to claim 2 , wherein the control unit connects the first switching unit to the power supply immediately before the load unit starts a predetermined heavy-load operation.
11. The power supply unit according to claim 3 , wherein the control unit connects the first switching unit to the power supply immediately before the load unit starts a predetermined heavy-load operation.
12. The power supply unit according to claim 4 , wherein the control unit connects the first switching unit to the power supply immediately before the load unit starts a predetermined heavy-load operation.
13. The power supply unit according to claim 5 , wherein the control unit connects the first switching unit to the power supply immediately before the load unit starts a predetermined heavy-load operation.
14. The power supply unit according to claim 2 , wherein after the load unit performs a predetermined heavy-load operation, when the power supply voltage is not less than a voltage determined based on a voltage necessary for driving the load unit using the step-down voltage supplied from the voltage step-down circuit, the control unit connects the first switching unit to the voltage step-down circuit.
15. The power supply unit according to claim 1 , further comprising:
a plurality of internal clocks,
wherein the control unit switches the plurality of internal clocks after switching the voltage supplied to the first power supply circuit in accordance with the properties or operation of the load driving unit.
16. The power supply unit according to claim 15 , wherein when a clock faster than the slowest clock of the plurality of internal clocks is used, the control unit does not switch the voltage supplied to the first power supply circuit and the voltage supplied to the second power supply circuit in accordance with the properties or operation of the load driving unit to which the power supply circuit supplies a voltage.
17. The power supply unit according to claim 1 ,
wherein the load unit is a sensor,
wherein the first power supply circuit is a sensor driving power supply circuit that supplies a voltage to a sensor driving unit that drives the sensor, and
wherein the second power supply circuit is a logic power supply circuit that supplies a voltage to a logic unit that includes the control unit.
18. An electronic timepiece comprising the power supply unit according to claim 1 .
19. A power supply unit comprising:
a first power supply circuit that supplies a voltage to a load driving unit that drives a load unit;
a second power supply circuit that supplies a voltage to circuits other than the load driving unit; and
a control unit that switches a voltage supplied to the first power supply circuit and a voltage supplied to the second power supply circuit in accordance with properties of the load driving unit;
wherein the load unit is a liquid crystal display device;
wherein the first power supply circuit is an LCD driving power supply circuit that supplies a voltage to an LCD driving unit that drives the liquid crystal display device; and
wherein the second power supply circuit is a logic power supply circuit that supplies a voltage to a logic unit that includes the control unit.