An LED circuit (2, 3), comprising: a plurality of (22, 32) LED devices (U0, U1,..., UN) coupled to form a series of LED devices, each of which includes an LED unit (UOL, U1L,..., UNL) and an integrated circuit unit (UOI, U1I,..., UNI) having a specific serial number (0, 1,..., N) and adapted to receive an electrical parameter; a power supply circuit; and a signal control circuit (23, 33) coupled between the power supply circuit and the plurality of LED devices (22, 32), and adapted to transmit a variation of the electric parameter carrying a signal code to each of the integrated circuit units (UOI, U1I,..., UNI), wherein a specific LED unit (UOL, U1L,..., UNL) is driven by a corresponding integrated circuit unit (UOI, U1I,..., UNI) when the signal code corresponds to the specific serial number (0, 1,..., N) of the corresponding integrated circuit unit (UOI, U1I,..., UNI), characterized in that each of the integrated circuit units (UOI, U1I,..., UNI) includes: a power voltage detecting circuit adapted to detect the variation of the electrical parameter, wherein the variation includes a change of a power voltage having a working frequency; an oscillator circuit adapted to provide a reference frequency; a frequency range detecting circuit adapted to receive the reference frequency and determine whether the working frequency is within an acceptable range; a serial number comparing circuit adapted to determine whether the specific serial number (0, 1,..., N) of the integrated circuit unit (UOI, U1I,..., UNI) corresponds to the signal code when the working frequency is within the acceptable range, wherein the signal code includes an identification code and an information; and a signal storage circuit adapted to receive the signal code and store the information when the specific serial number (0, 1,..., N) and the identification code are the same. a plurality of (22, 32) LED devices (U0, U1,..., UN) coupled to form a series of LED devices, each of which includes an LED unit (UOL, U1L,..., UNL) and an integrated circuit unit (UOI, U1I,..., UNI) having a specific serial number (0, 1,..., N) and adapted to receive an electrical parameter; a power supply circuit; and a signal control circuit (23, 33) coupled between the power supply circuit and the plurality of LED devices (22, 32), and adapted to transmit a variation of the electric parameter carrying a signal code to each of the integrated circuit units (UOI, U1I,..., UNI), wherein a specific LED unit (UOL, U1L,..., UNL) is driven by a corresponding integrated circuit unit (UOI, U1I,..., UNI) when the signal code corresponds to the specific serial number (0, 1,..., N) of the corresponding integrated circuit unit (UOI, U1I,..., UNI), characterized in that each of the integrated circuit units (UOI, U1I,..., UNI) includes: a power voltage detecting circuit adapted to detect the variation of the electrical parameter, wherein the variation includes a change of a power voltage having a working frequency; an oscillator circuit adapted to provide a reference frequency; a frequency range detecting circuit adapted to receive the reference frequency and determine whether the working frequency is within an acceptable range; a serial number comparing circuit adapted to determine whether the specific serial number (0, 1,..., N) of the integrated circuit unit (UOI, U1I,..., UNI) corresponds to the signal code when the working frequency is within the acceptable range, wherein the signal code includes an identification code and an information; and a signal storage circuit adapted to receive the signal code and store the information when the specific serial number (0, 1,..., N) and the identification code are the same. a power voltage detecting circuit adapted to detect the variation of the electrical parameter, wherein the variation includes a change of a power voltage having a working frequency; an oscillator circuit adapted to provide a reference frequency; a frequency range detecting circuit adapted to receive the reference frequency and determine whether the working frequency is within an acceptable range; a serial number comparing circuit adapted to determine whether the specific serial number (0, 1,..., N) of the integrated circuit unit (UOI, U1I,..., UNI) corresponds to the signal code when the working frequency is within the acceptable range, wherein the signal code includes an identification code and an information; and a signal storage circuit adapted to receive the signal code and store the information when the specific serial number (0, 1,..., N) and the identification code are the same.