Converter for led light in constant current type and led light apparatus using it

Of the constant current output method according to the first invention of the present application LED lighting converters, in the LED lighting converter for switching the at least two LED strings, the constant current output DC-DC converting a predetermined input voltage to a direct current voltage of a constant-current conversion section .; A plurality of open detection circuit, and each of the plurality of open-detecting circuit is parallel connected to each of the LED string, said open detector circuit is an open detection signal when the opening LED electrically in parallel connected to the LED string generated opening detection section for the output; And coupled to each end of the LED string, a switch group including a plurality of switches for switching to the open detection signal.