Daily Archives: March 13, 2009

LED lighting

Apropos has 10 overhead dome lights and 6 floor-level courtesy lights that use incadescent bulbs. Each bulb is 10W which means each light draws about 1A of current. Replacing the bulb with LED lighting would reduce the current draw by 1/10th. It is important when cruising to keep the amp-hours to a minimum, and the conversion to LED would help.

One solution is to use HBLEDs (high-brightness LEDs).  A drive circuit is needed to source the proper current through a string of HBLEDs.  I want to use a PSoC chip since I’ve spent the past 10 years helping to design it at Cypress Semiconductor.  It’s a reconfigurable 8-bit micro-controller that can be configured for LED driving.  The driver would consist of a PWM (pulse width modulator) NFET gate drive.  Setting the PWM would control the brightness of the LEDs.  External components would be the NFET, an inductor, a flyback diode, a capacitor, and a voltage regulator.  These could be placed on a small board along with the 4-5 HBLEDs and the PSoC chip. An option would be to have 5 red LEDs and 5 white LEDs and a switch to select either red (for night-time cruising where you want to retain night vision when going below deck) or white.  One PSoC chip could drive both circuits.

Share