Patent ID: 9723674
Date: 2017-08-01
CPC Classifications: G02F,H05B

Claim:
1. A current driver which is connected with light emitting diode (LED) bars of the maximum number N of channels (N is an integer of 2 or more) and drives LED bars of M channels (1≦M≦N) designated to be driven, comprising: a PWM input terminal configured to receive an external dimming pulse subjected to pulse width modulation (PWM), the external dimming pulse having a duty cycle according to a target light quantity common to the LED bars of the M channels; a pulse measurement circuit configured to measure a period and a pulse width of the external dimming pulse and generate a digital period data and a pulse width data; an interface circuit which is connected to an external processor and is configured to receive (i) an enable data to designate the LED bars of M channels to be driven and (ii) a phase difference setting data to designate one of a plurality of selectable phase differences 360°/2, 360°/3, . . . , 360°/N; a plurality of M current sources which correspond to the M channels to be driven and are respectively connected with corresponding LED bars, and which are configured to be switched between On and Off in response to an internal dimming pulse; and a pulse generator configured to generate M internal dimming pulses having a period represented by the period data, a pulse width represented by the pulse width data, and a phase difference according to the phase difference setting data, and to distribute the generated M internal dimming pulses to the M current sources.