Power switching circuit for liquid crystal display

1. A power switching circuit comprising:

a control signal input terminal configured for receiving a control signal;

an output terminal configured to be connected to a load circuit;

a direct current (DC) power supply;

a first transistor comprising a control electrode connected to the control signal input terminal, a first current conducting electrode, and a second current conducting electrode connected to ground;

a second transistor comprising a control electrode connected to the first current conducting electrode of the first transistor via a discharging resistor and a diode and further connected to the DC power supply via a discharging capacitor, a first current conducting electrode connected to the DC power supply, and a second current conducting electrode connected to the output terminal; and

a third transistor comprising a control electrode connected to the first current conducting electrode of the first transistor, a first current conducting electrode connected to the output terminal, and a second current conducting electrode connected to ground.

2. The power switching circuit as claimed in claim 1 , further comprising a first current limiting resistor connected between the control electrode of the first transistor and the control signal input terminal.

3. The power switching circuit as claimed in claim 1 , further comprising a 3.3V DC power supply, and a first bias resistor connected between control signal input terminal and the 3.3V DC power supply.

4. The power switching circuit as claimed in claim 1 , further comprising at least one filter capacitor connected between the output terminal and ground.

5. The power switching circuit as claimed in claim 1 , further comprising at least one filter capacitor connected between DC power supply and ground.

6. The power switching circuit as claimed in claim 5 , wherein the DC power supply is a 5V DC power supply.

7. The power switching circuit as claimed in claim 1 , further comprising a second bias resistor connected between the first conducting electrode of the first transistor and the DC power supply.

8. The power switching circuit as claimed in claim 1 , further comprising a third bias resistor connected between the first current conducting electrode of the third transistor and the output terminal.

9. The power switching circuit as claimed in claim 1 , further comprising a second current limiting resistor connected between the control electrode of the second transistor and the conducting electrode of the first transistor.

10. The power switching circuit as claimed in claim 1 , wherein the control signal is a high level voltage or a low level voltage.

11. The power switching circuit as claimed in claim 1 , wherein the first transistor is an n-channel enhancement mode metal-oxide-semiconductor (NMOS) transistor.

12. The power switching circuit as claimed in claim 1 , wherein the first transistor is a negative-positive-negative (NPN) transistor.

13. The power switching circuit as claimed in claim 1 , wherein the second transistor is a p-channel enhancement mode metal-oxide-semiconductor (PMOS) transistor.

14. The power switching circuit as claimed in claim 1 , wherein the second transistor is a positive-negative-positive (PNP) transistor.

15. The power switching circuit as claimed in claim 1 , wherein the third transistor is an n-channel enhancement mode metal-oxide-semiconductor (NMOS) transistor.

16. The power switching circuit as claimed in claim 1 , wherein the third transistor is an negative-positive-negative (NPN) transistor.

17. The power switching circuit as claimed in claim 1 , wherein the load circuit is comprised in a liquid crystal display.