Patent ID: 7688009
Filing Date: 2010-03-30
Classification: H05B,Y02B

Abstract:
1. A current controller for an LED comprising: a switching control circuit configured to form a switching drive signal to control a current through an LED responsively to a sense signal that is representative of the current; a first control circuit configured to receive a control signal and responsively enable the switching control circuit to form the switching drive signal, the control signal having a first state during a first time interval and a second state during a second time interval; an error amplifier coupled to receive the sense signal and form a error signal; and a sample and hold circuit configured to sample a value of the error signal responsively to a first portion of the first time interval that the control signal is at the first state and hold the value of the error signal responsively to a portion of the second time interval that the control signal is at the second state to form a held value of the error signal, the sample and hold circuit configured to couple the held value to the switching control circuit responsively to a second portion of the first time interval that the control signal is at the first state and couple the error signal to the switching control circuit after the second portion of the first time interval.