Power control circuit with coupling circuit for controlling output power sequence and liquid crystal display using same

1. A power control circuit, comprising:

a scaler circuit configured for outputting a control signal;

a voltage converter configured for converting a received voltage into a plurality of desired voltages;

a first control unit configured for controlling whether a first voltage is applied to the voltage converter according to the control signal;

a second control unit configured for controlling whether to transmit a second voltage applied to the second control unit; and

a coupling circuit connected in series between the first and second control units, the coupling circuit enabling the second control unit to function ahead of the voltage converter according to the control signal

wherein the first control unit comprises a first transistor, the first transistor comprises a source electrode capable of receiving the first voltage, a drain electrode connected to the voltage converter, and a gate electrode coupled to the coupling circuit; wherein the first control unit further comprises a third transistor, the third transistor comprises a base electrode connected to the scaler circuit, a emitter electrode that is grounded, and a collector electrode connected to the gate electrode of the first transistor; wherein the first control unit further comprises a fourth transistor, the fourth transistor comprises a gate electrode connected to the gate electrode of the first transistor via a resistor, a source electrode being grounded, and a drain electrode connected to the drain electrode of the first transistor via another resistor.

2. The power control circuit of claim 1 , wherein the coupling circuit comprises a coupling resistor and a coupling capacitor connected in parallel, the first control unit connected to the second control unit via the coupling resistor and the coupling capacitor respectively.

3. The power control circuit of claim 2 , wherein the second control unit comprises a second transistor, the second transistor comprises a emitter electrode for receiving the second voltage, a collector electrode for outputting the second voltage, and a base electrode connected to the coupling circuit.

4. The power control circuit of claim 3 , wherein the second control unit comprises a second resistor connected between the emitter and base electrodes of the second transistor.

5. The power control circuit of claim 3 , wherein the base electrode of the second transistor is connected to the gate electrode of the first transistor via the coupling resistor and the coupling capacitor.

6. The power control circuit of claim 1 , wherein the first control unit further comprises a first resistor connected between the source and gate electrodes of the first transistor.

7. A power control circuit, comprising:

a scaler circuit configured for outputting a control signal;

a voltage converter configured for converting a received voltage into a plurality of desired voltages;

a first control unit configured for controlling whether a first voltage is applied to the voltage converter according to the control signal;

a second control unit configured for controlling whether to transmit a second voltage applied to the second control unit; and

a coupling circuit connected in series between the first and second control units, the second control unit receiving the control signal via the coupling circuit, and the coupling circuit enabling the second control unit to function ahead of the voltage converter according to the control signal.

8. The power control circuit of claim 7 , wherein the first control unit comprises a first transistor, the first transistor comprises a source electrode capable of receiving the first voltage, a drain electrode connected to the voltage converter, and a gate electrode coupled to the coupling circuit.

9. The power control circuit of claim 8 , wherein the first control unit further comprises a resistor connected between the source and gate electrodes of the first transistor.

10. The power control circuit of claim 8 , wherein the second control unit comprises a second transistor, the second transistor comprises a emitter electrode for receiving the second voltage, a collector electrode for outputting the second voltage, and a base electrode connected to the first control unit via the coupling circuit.

11. The power control circuit of claim 10 , wherein the second control unit comprises a second resistor connected between the emitter and base electrodes of the second transistor.

12. The power control circuit of claim 10 , wherein the first control unit further comprises a third transistor, the third transistor comprises a base electrode connected to the scaler circuit, a emitter electrode that is grounded, and a collector electrode connected to the gate electrode of the first transistor.

13. The power control circuit of claim 12 , wherein the first control unit further comprises a fourth transistor, the fourth transistor comprises a gate electrode connected to the gate electrode of the first transistor via a first resistor, a source electrode being grounded, and a drain electrode connected to the drain electrode of the first transistor via a second resistor.

14. The power control circuit of claim 10 , wherein the coupling circuit comprises a coupling resistor and a coupling capacitor connected in parallel, the base electrode of the second transistor is connected to the gate electrode of the first transistor via the coupling resistor and the coupling capacitor respectively.

15. The power control circuit of claim 7 , wherein the coupling circuit comprises a coupling resistor and a coupling capacitor connected in parallel, the first control unit connected to the second control unit via the coupling resistor and the coupling capacitor respectively.

16. The power control circuit of claim 15 , the first control unit comprises a first transistor, the first transistor comprises a source electrode capable of receiving the first voltage, a drain electrode connected to the voltage converter, and a gate electrode coupled to the gate electrode of the second transistor via the coupling resistor and the coupling capacitor respectively.

17. The power control circuit of claim 16 , wherein the second control unit comprises a second transistor, the second transistor comprises a emitter electrode for receiving the second voltage, a collector electrode for outputting the second voltage, and a base electrode connected to the first control unit via the coupling resistor and the coupling capacitor respectively.

18. The power control circuit of claim 17 , wherein the second control unit comprises a resistor connected between the emitter and base electrodes of the second transistor.

19. The power control circuit of claim 17 , wherein the first control unit further comprises a third transistor, the third transistor comprises a base electrode connected to the scaler circuit, a emitter electrode that is grounded, and a collector electrode connected to the gate electrode of the first transistor.

20. The power control circuit of claim 19 , wherein the first control unit further comprises a fourth transistor, the fourth transistor comprises a gate electrode connected to the gate electrode of the first transistor via a first resistor, a source electrode being grounded, and a drain electrode connected to the drain electrode of the first transistor via a second resistor.