The Boost converter switching topology can be used to drive a series string of LEDs with constant current when the available system input voltage is lower than the required combined forward voltage drop of the LEDs.
Many security or emergency lighting applications use a lead-acid battery to provide power during a mains power failure. In these applications, the battery terminal voltage could be 12Vdc or 24Vdc and series string of LEDs may require a combined forward voltage in excess of this value.
The design presented in this article runs from 12Vdc to 24Vdc input, driving ten series-connected Luxeon K2 LEDs at 1A with an electrical conversion efficiency of 95% and 35W total output power capability
The design presented in this article runs from 12Vdc to 24Vdc input, driving ten series-connected Luxeon K2 LEDs at 1A with an electrical conversion efficiency of 95% and 35W total output power capability