Chuk LED Power Supply

A 300 watt Chuk power supply for driving a LED searchlight in a rescue submarine.  I needed a step up/down regulator with a low ripple current, Chuk seemed like a good match.  The output is dimmable using PWM at the switching frequency, rather than applying a lower frequency PWM modulation.  This avoids problems with flickering when using cameras.  The output is short circuit proof and, more importantly for a constant current supply, open circuit proof.  The switcher is run entirely from an Atmel AT90PWM2 with considerable attention given to recovering from crashes.  The photograph is of the first hand built prototype, the production parts looked rather neater.  You may be wondering why a Chuk has two inductors.  Most volume designs use the leakage inductance of the main transformer, but this can be tricky to get right and I was in a hurry.