We are in the process of gathering requirements for a buck switching power supply design that has an input voltage of 18V and will supply a fixed 12V to an LED strip at 2.45A. This LED strip will be PWM’d for dimming control and I’d like to get support on the best approach for this type of application. Some concerns I have are about the PWM frequency vs. the bandwidth and/or switching frequency of the switching regulator.
I want to clarify that this is a fixed-voltage LED strip, not a string of LEDs. This LED strip has its own current-limiting resistors and just takes a fixed 12V input. The 12V input is PWM'd to adjust the brightness. For reference, I have drawn a diagram to represent the architecture that we are trying to use and that we are trying to design/choose a 12V regulator for. Effectively, the LED strips we are driving are cuttable LED lighting strips that have two sets (one for each color) of three LEDs in series every 50 mm. Each same-color set of three LEDs is in parallel with the next 50 mm set and connected to the 12V bus built into the strip. I’ve attempted to draw a schematic of effectively two 50 mm sections in the architecture diagram below.
