THREE-STATE SWITCH FOR POWER SUPPLY CIRCUIT

Abstract

A three-state switch includes a first input terminal, a first output terminal, a second output terminal, a pole, a first throw, a second throw, and a third throw. The first input terminal is for receiving a first signal. The first output terminal is coupled to the first input terminal, and for outputting a second signal. The second output terminal is for outputting a third signal. The first throw is for contacting with the pole to have the three-state switch output the second signal, and not output the third signal. The second throw is for contacting with the pole to have the three-state switch not output the second signal and the third signal. The third throw is for contacting with the pole to have the three-state switch output the second signal and the third signal. When the pole is suspended, the first output terminal outputs the second signal.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the present three-state switch and a power supply circuit using the same can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present device. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.

FIG. 1 is a block diagram showing a power supply circuit and a load in accordance with a first exemplary embodiment, the power supply circuit including a three-state switch;

FIG. 2 is a circuit diagram of the three-state switch of FIG. 1;

FIG. 3 is a block diagram showing a power supply circuit and a load in accordance with a second exemplary embodiment, the power supply circuit including a three-state switch;

FIG. 4 is a circuit diagram of the three-state switch of FIG. 3;

FIG. 5 is a block diagram showing a traditional power supply circuit and a load, the traditional power supply circuit including a traditional three-state switch; and

FIG. 6 is a circuit diagram of the three-state switch of FIG. 5.

Claims

1. A three-state switch comprising: a first input terminal for receiving a first signal;a first output terminal coupled to the first input terminal for outputting a second signal based on the first signal;a second output terminal for outputting a third signal;a first throw;a second throw;a third throw; anda pole selectively contacting with one of the first throw, the second throw, and the third throw, the first output terminal being enabled to output the second signal during a time interval when the pole contacts with none of the first throw, the second throw, and the third throw.

2. The three-state switch according to claim 1, wherein the first throw remains suspended, the second throw is coupled to a virtual ground point, the third throw is coupled to the second output terminal, and the pole is coupled to the first output terminal.

3. The three-state switch according to claim 1, wherein the first throw is coupled to a node that is coupled to the second output terminal.

4. The three-state switch according to claim 3, wherein the three-state switch comprises a second input terminal being coupled to the node.

5. The three-state switch according to claim 4, wherein the second throw is coupled between the first input terminal and the first output terminal.

6. The three-state switch according to claim 5, wherein the third throw remains suspended.

7. The three-state switch according to claim 6, wherein the pole is coupled to a virtual ground point.

8. A power supply circuit for supplying an operating voltage and a holding signal to a load, the power supply circuit comprising: a direct current for outputting an initial voltage;a regulator coupled to the direct current for receiving the initial voltage;a three-state switch coupled to the direct current and the regulator, the three-state switch comprising:a first input terminal coupled to the direct current;a first output terminal coupled to the first input terminal and the regulator, for outputting; anda second output terminal for outputting the holding signal; the three-state switch having a first state in which the first output terminal outputs a driving signal to have the regulator output the operating voltage and the second output terminal is disabled, and a second state in which the first output terminal outputs the driving signal to the regulator and the second output terminal outputs a holding signal to hold a present state of the load, during a switching procedure between the first state and the second state, the first output terminal keeps outputting the driving signal to the regulator.

9. The power supply circuit according to claim 8, wherein the three-state switch comprises a third state in which both the first output terminal and the second output terminal are disabled.

10. The power supply circuit according to claim 9, wherein the three-state switch comprises a pole and a first throw for contacting with the pole to set the three-state switch in the first state.

11. The power supply circuit according to claim 10, wherein the three-state switch comprises a second throw for contacting with the pole to set the three-state switch in the second state.

12. The power supply circuit according to claim 11, wherein the three-state switch comprises a third throw for contacting with the pole to set the three-state switch in the third state.

13. A three-state switch comprising: a first input terminal for receiving a first signal;a first output terminal;a second output terminal;wherein the three-state switch having a first state in which the first output terminal outputs a second signal based on the first signal and the second output terminal is disabled, and a second state in which the first output terminal outputs the second signal and the second output terminal outputs a third signal, during a switching procedure between the first state and the second state, the first output terminal keeps outputting the second signal.

14. The three-state switch according to claim 13, wherein the three-state switch comprises a third state in which the first output terminal and the second output terminal are both disabled.

15. The three-state switch according to claim 14, wherein the three-state switch comprises a pole and a first throw for contacting with the pole to set the three-state switch in the first state, a second throw for contacting with the pole to set the three-state switch in the second state, and a third throw for contacting with the pole to set the three-state switch in the third state.

16. The three-state switch according to claim 15, wherein the first throw remains suspended, the second throw is coupled to a virtual ground point, the third throw is coupled to the second output terminal, and the pole is coupled to the first output terminal.