Power supply switching circuit, real time clock device, electronic apparatus, mobile unit, and method of controlling power supply switching circuit
First Claim
Patent Images
1. A power supply switching circuit comprising:
- a first power supply node configured to electrically couple to a first power supply;
a second power supply node electrically coupled to a second power supply;
a power supply monitoring circuit that intermittently monitors a voltage at the first power supply node;
a switching circuit that connects and disconnects the first power supply node and the second power supply node; and
a switch control circuit that switches a mode from a first mode to a second mode according to an output signal of the power supply monitoring circuit, wherein;
the switch control circuit controls the power supply monitoring circuit to have the power supply monitoring circuit intermittently monitor the voltage at the first power supply node by intermittently providing an enable signal to turn on the power supply monitoring circuit,in the first mode, the first power supply node supplies power to a load, the switching circuit intermittently connects the first power supply node and the second power supply node, the power supply monitoring circuit is enabled to monitor the voltage at the first power supply node when the switch circuit is open to disconnect the second power supply node and the first power supply, and the power supply monitoring circuit is disabled from monitoring of the voltage at the first power supply node when the switch circuit is closed to connect the second power supply node and the first power supply, andin the second mode, the switching circuit disconnects the first power supply node and the second power supply node, the power supply monitoring circuit is intermittently enabled to monitor the voltage at the first power supply node for a predetermined time period, and the second power supply node supplies power to the load.
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Abstract
A power supply switching circuit includes a switching circuit that electrically connects a VCC terminal and a VBK terminal in a connected state, a switch control circuit, and a power supply monitoring circuit that monitors a voltage of the VCC terminal, and outputs a voltage of the VBK terminal. The switch control circuit switches a mode from a normal mode in which the switching circuit is intermittently connected to a standby mode in which the switching circuit is opened according to an output signal of the power supply monitoring circuit.
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Citations
12 Claims
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1. A power supply switching circuit comprising:
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a first power supply node configured to electrically couple to a first power supply; a second power supply node electrically coupled to a second power supply; a power supply monitoring circuit that intermittently monitors a voltage at the first power supply node; a switching circuit that connects and disconnects the first power supply node and the second power supply node; and a switch control circuit that switches a mode from a first mode to a second mode according to an output signal of the power supply monitoring circuit, wherein; the switch control circuit controls the power supply monitoring circuit to have the power supply monitoring circuit intermittently monitor the voltage at the first power supply node by intermittently providing an enable signal to turn on the power supply monitoring circuit, in the first mode, the first power supply node supplies power to a load, the switching circuit intermittently connects the first power supply node and the second power supply node, the power supply monitoring circuit is enabled to monitor the voltage at the first power supply node when the switch circuit is open to disconnect the second power supply node and the first power supply, and the power supply monitoring circuit is disabled from monitoring of the voltage at the first power supply node when the switch circuit is closed to connect the second power supply node and the first power supply, and in the second mode, the switching circuit disconnects the first power supply node and the second power supply node, the power supply monitoring circuit is intermittently enabled to monitor the voltage at the first power supply node for a predetermined time period, and the second power supply node supplies power to the load. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method of controlling a power supply switching circuit including a power supply monitoring circuit that monitors a voltage of a first power supply node when the power supply monitoring circuit receives an enable signal to turn on the power supply monitoring circuit and a switching circuit that electrically connects and disconnects the first power supply node and a second power supply node, wherein the first supply node is configured to connect to a first power source and the second power supply node is connected to a second power source, the method comprising:
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switching a mode from a first mode to a second mode according to an output signal of the power supply monitoring circuit, wherein in the first mode, the switching circuit intermittently connects the first power supply node and the second power supply node and the first power supply node supplies a voltage to a load, and in the second mode, the switching circuit disconnects the first power supply node and the second power supply node, and the second power supply node supplies a voltage to the load; in the second mode, intermittently providing the enable signal to the power supply monitoring circuit to monitor the voltage at the first power supply node for a predetermined time period; in the first mode, providing the enable signal to the power supply monitoring circuit to monitor the voltage at the first power supply node in response to the switching circuit being open to disconnect the second power supply node and the first power supply; and in the first mode, not providing the enable signal to the power supply monitoring circuit to disable monitoring the voltage at the first power supply node in response to the switching circuit being closed to connect the second power supply node and the first power supply during the first mode.
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Specification