A very simple economy high brightness led flashlight circuit can be made using a simple AC-DC converter from some other unused device like an mobile phone, and some common resistors and high brightness leds.
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.
The LTC3600 LED driver circuit is manufactured by Linear Technology, and can be used for design a very simple high efficiency LED driver circuit with programmable dimming control .
LTC3600 is a monolithic synchronous buck regulator whose output is programmed with just one external resistor.