a channel data setting circuit and a light emitting element drive circuit using the channel data setting circuit are disclosed . a channel data setting circuit includes a clock unit that measures one of a low level period and a high level period of a pulse signal supplied from a single input terminal , and plural counter units in which different predetermined ranges corresponding to plural channels are set . each of the counter units is adapted to enable a count when the period measured by the clock unit has a length within the corresponding predetermined range . the value of the count is used as a channel data item for the corresponding channel .