US Patent 9699839 Multichannel constant current LED controlling circuit and controlling method

A multichannel constant current LED controlling circuit can include: (i) a control loop configured to generate a first control signal in accordance with a current feedback signal that represents a driving current flowing through an LED load, where the LED load comprises a plurality of LED strings coupled in series; (ii) a loop steady state network comprising a plurality of steady state holding components configured to hold a plurality of steady state control signals that correspond to a plurality of load states of the LED load, where when a state of the LED load varies, at least one of the steady state holding components is selected by the control loop to generate the first control signal; and (iii) a power switching transistor of a power stage circuit configured to generate a pseudo-constant output current to drive the LED load.