Test circuit and method for an electronic device

1. A test circuit for an electronic device comprising a liquid crystal display (LCD), the test circuit comprising:

a pulse width modulator (PWM) to provide voltages to a display panel of the LCD;

a plurality of feedback circuits to output feedback voltages to the PWM;

a power supply to provide an operating voltage for the PWM; and

a controller to output a control voltage to the feedback circuits in response to the electronic device being in a test mode, the controller comprising a trigger end;

wherein, when the electronic device is in the test mode, the power supply provides the operating voltage to the controller and the controller outputs the control voltage accordingly, and the plurality of feedback circuits respectively decrease the feedback voltages according to the control voltage, such that the PWM increases the voltages output to the display panel according to the feedback voltages, and the increased voltages reach predetermined test voltages to test the electronic device; and

when the electronic device is in an operating mode, the trigger end of the controller does not receive the operating voltage from the power supply, and the controller does not output the control voltage according to the trigger end.

2. The test circuit for the electronic device of claim 1 , wherein the feedback circuits comprise a first feedback circuit, the PWM comprises a first feedback terminal connected to the first feedback circuit, and wherein when the first feedback circuit receives the control voltage, the first feedback circuit decreases a resistance between the first feedback terminal and ground, and the voltage of the first feedback terminal decreases.

3. The test circuit for the electronic device of claim 2 , wherein the first feedback circuit comprises a first voltage divider to feed a voltage back to the first feedback terminal of the PWM and a first resistor, and wherein when the first feedback circuit receives the control voltage, the first resistor is connected between the first feedback terminal and the ground.

4. The test circuit for the electronic device of claim 3 , wherein the feedback circuits further comprise a second feedback circuit and the PWM further comprises a second feedback terminal connected to the second feedback circuit, and wherein when the second feedback circuit receives the control voltage, the second feedback circuit decreases a resistance between the second feedback terminal and ground, and the voltage of the second feedback terminal decreases.

5. The test circuit for the electronic device of claim 4 , wherein the PWM further comprises a second voltage divider to feed a voltage back to the second feedback terminal of the PWM and a second resistor, and wherein when the second feedback circuit receives the control voltage, the second resistor is connected between the second feedback terminal and the ground.

6. The test circuit for the electronic device of claim 5 , wherein the feedback circuits further comprise a third feedback circuit, the PWM further comprises a third feedback terminal connected to the third feedback circuit, and wherein when the third feedback circuit receives the control voltage, the third feedback circuit decreases a resistance between the third feedback terminal and ground, and the voltage of the third feedback terminal decreases.

7. The test circuit for the electronic device of claim 6 , wherein the PWM further comprises a third voltage divider to feed a voltage back to the third feedback terminal of the PWM and a third resistor, and wherein when the third feedback circuit receives the control voltage, the third resistor is connected between the third feedback terminal and the ground.

8. The test circuit for the electronic device of claim 1 , wherein the operating voltage is a 5V direct current (DC) voltage.

9. The test circuit for the electronic device of claim 1 , wherein a software application controls a time of the test.

10. A test circuit for an electronic device comprising a liquid crystal display (LCD), the test circuit comprising:

a pulse width modulator (PWM) to provide voltages to a display panel of the LCD;

a plurality of feedback circuits to output feedback voltages to the PWM;

a power supply to provide an operating voltage for the PWM; and

a controller to output a control voltage to the feedback circuits in response to the electronic device being in a test mode, the controller comprising a trigger end, a reset circuit, and a reset terminal to charge the reset circuit;

wherein, when the electronic device is in the test mode, the power supply provides the operating voltage to the controller, the controller outputs the control voltage accordingly, and the plurality of feedback circuits respectively decrease the feedback voltages according to the control voltage, such that the PWM increases the voltages output to the display panel according to the feedback voltages, and the increased voltages reach predetermined test voltages to test the electronic device; and

when a voltage of the reset terminal reaches a predetermined voltage, the controller stops the control voltage according to the reset terminal.

11. The test circuit for the electronic device of claim 10 , wherein the reset circuit comprises a resistor and a capacitor and the reset terminal is grounded via the resistor and the capacitor.

12. The test circuit for the electronic device of claim 10 , further comprising a direct current (DC) voltage converter connected between the power supply and the controller, wherein the operating voltage is a 5V DC voltage, and the voltage converter converts the 5V DC voltage to a 3.3V DC voltage, the 3.3V DC voltage being another operating voltage for the controller.

13. A test method for an electronic device, the method comprising:

providing a liquid crystal display (LCD) device, the LCD device comprising a pulse width modulator (PWM) to provide voltages to a display panel of the LCD and a plurality of feedback circuits to output feedback voltages to the PWM;

providing a power supply to provide an operating voltage to the PWM;

providing a controller to output a control voltage to the feedback circuits in response to the electronic device being in a test mode, wherein the controller comprises a trigger end; and when the electronic device is in the test mode, the power supply provides the operating voltage to the controller and the controller outputs the control voltage accordingly; and when the electronic device is in an operating mode, the trigger end of the controller does not receive the operating voltage from the power supply, and the controller does not output the control voltage according to the trigger end; and

decreasing voltages of the feedback voltages using the feedback circuits when the electronic device is in the test mode, and increasing the voltages output to the display panel according to the feedback voltages using the PWM, wherein the increased voltages reach predetermined test voltages to test the electronic device.

14. The test method of claim 13 , wherein the operating voltage is a 5V direct current (DC) voltage.