A novel LED driver circuit, including: a current regulation circuit, having a first end and a second end, wherein a first current is flowing into the second end, and a voltage difference between the first end and the second end is generated in response to the first current; a transistor, coupled with the first end and second end of the current regulation circuit; a bias network, having a first end and a second end, the second end being coupled with the transistor; and a LED module, having at least two connection nodes, wherein the connection node at one end of the LED module is coupled to a line voltage, the connection node at the other end of the LED module is coupled to the transistor, and one of the at least two connection nodes is coupled with the first end of the bias network.