OVER-VOLTAGE AND OVER-CURRENT PROTECTION CIRCUITS AND ELECTRONIC DEVICES

摘要

The present invention provides an over-voltage and over-current protection circuit (30), including an over-voltage detection unit (31) to generate an over-voltage detection voltage, an over-current detection unit (32) to generate an over-current detection voltage, a LED driving unit (33) being connected with the over-voltage detection unit and the over-current detection unit to converter a reference voltage into an over-voltage reference voltage and an over-current reference voltage being proportional to the reference voltage, a reference voltage adjusting unit (34) and a control unit (35). The control unit (35) outputs a boost control signal with a high level when it judges that change range of the working voltage of the LED module (20) exceeds a predetermined value according to a LED characteristic data curve. The present invention provides an electronic device (1), the over-voltage or over-current protection threshold could be increased along with increasing the working time of the electronic device (1).

主权项

1. An over-voltage and over-current protection circuit being used for a LED module of an electronic device which being supplied by a power source, the LED module comprising a positive input and the power source comprising an output, wherein the over-voltage and over-current protection circuit comprise:
an over-voltage detection unit being connected between the positive input end and ground to detect the voltage of the positive input of the LED module to generate an over-voltage detection voltage being proportional to the positive input voltage; an over-current detection unit being connected between the output end of the power source and the ground to detect the current of the LED module to generate an over-current detection voltage being proportional to the positive input current; a LED driving unit being connected with the over-voltage detection unit and the over-current detection unit to converter a reference voltage into an over-voltage reference voltage and an over-current reference voltage being proportional to the reference voltage, the LED driving unit comparing respectively the over-voltage reference voltage and the over-current reference voltage to the over-voltage detection voltage to decide whether to perform an over-current or over-voltage protection; a reference voltage adjusting unit outputting the reference voltage to the LED driving unit; and a control unit storing LED characteristic data curve reflecting a changing relationship between the working voltage of the LED module and the time, the reference voltage adjusting unit increasing the outputting reference voltage when the control unit judges that change range of the working voltage of the LED module exceeding a predetermined value according to the LED characteristic data curve.