A 4-W White LED Driver Circuit

Here is a white LED driver circuit for four 1W white LEDs powered by one Li-ion battery cell.  It is a boost converters with current limit to about 400mA.  The converter frequency is about 35KHz with 80% duty cycle.  The current draw from the supply is 1.4A average with 0.5A ripple.  The current delivered to the LEDs are 0.3A.  The prototype achieves about 72% efficiency, matching the simulation very well.