This dimming controlled LED driver circuit is designed using LM3409 
P-channel MosFET controller for step-down (buck) current regulators.The 
LM3409 devices use Constant Off-Time (COFT) control to regulate an 
accurate constant current without the need for external control loop 
compensation Dimming controlled LED driver electronic circuit require an
 input voltage of 36 volts and will provide at output a voltage of 24 
volts at a maximum current of 700mA 
Components list