LED driving apparatus having holding current circuit and operating method thereof

摘要

A LED driving apparatus having a holding current circuit and an operating method thereof are disclosed. The holding current circuit includes an input terminal, a holding resistor, a regulator, a first resistor, a second resistor, a setup resistor, a control unit, and a transistor. The holding resistor and the regulator, the first resistor and the second resistor, and the transistor and the setup resistor are coupled between the input terminal and ground terminal respectively. The control unit is coupled to the transistor, between the holding resistor and the regulator, and between the first resistor and the second resistor respectively. The control unit receives a first voltage between the holding resistor and the regulator and a second voltage between the first resistor and the second resistor and outputs a control signal to selectively control the transistor off.

主权项

1. A holding current circuit of a LED driving apparatus, comprising:
an input terminal, for receiving an input voltage; a holding resistor, coupled to the input terminal; a regulator, coupled between the holding resistor and a ground terminal; a first resistor, coupled to the input terminal; a second resistor, coupled between the first resistor and the ground terminal; a setup resistor, coupled to the ground terminal; a control unit, coupled to a transistor, between the holding resistor and the regulator, and between the first resistor and the second resistor respectively, for receiving a first voltage between the holding resistor and the regulator and a second voltage between the first resistor and the second resistor and outputting a control signal; and the transistor, coupled to the input terminal, the setup resistor, and the control unit respectively, for receiving the control signal and being selectively switched off by the control signal; wherein the control unit comprises: a third resistor, one end of the third resistor is coupled between the holding resistor and the regulator, another end of the third resistor is coupled to a gate of the transistor; and one end of a rectifier or a bipolar junction transistor (BJT), coupled between the third resistor and the gate of the transistor, another end between the first resistor and the second resistor and to the ground terminal respectively.