Is a buck converter okay for running a 100W COB, or do I need a proper driver?

A dedicated constant current driver is absolutely the better choice for this high-power COB setup, even though the generic buck converter seems like a cheap workaround. While you could try to dial in a buck converter to handle the voltage, you're running a massive thermal risk trying to keep the current perfectly regulated manually. Large COB chips need very specific, stable current to run at full efficiency and lifetime. An unregulated voltage supply might dip or spike under load, which is a fast way to destroy that expensive chip. The primary job of the driver here isn't just to convert voltage; it's to ensure the LED sees a precise amount of current, regardless of what the COB chip is doing internally. If the driver isn't designed for constant current, you're asking for thermal runaway or premature failure. Even if you manage to get it running with the buck converter, the heat dissipation requirements are massive. You're putting out a lot of wattage, and that energy has to go somewhere, which is why mounting it on a big heatsink is crucial. When you consider a dedicated LED driver, you get guaranteed dimming control, which is useful for your plan. You can set the driver to limit the maximum current to a safer level, ensuring the device doesn't overheat when you're at full brightness. And instead of hoping your buck converter maintains stability, you're using hardware specifically designed for this job. Focusing on a driver that is rated for the maximum current draw, even if you plan to run it below capacity, is the safest route for the longevity of the light source. Make sure that whatever driver you choose has plenty of heatsinking on its own board, not just relying on the COB mount. Always run the chip within its specified operating temprature range, beacuse every few degrees over that limit dramatically cuts down how long the LED will last.

I'm a little lost on the driver talk since I mostly just use standard power bricks for my other home stuff. My project involves addressable LEDs, so I'm trying to make the light change color relly fast. Does the stable current output from a dedicated driver matter much when you are trying to cycle the power on and off quickly to create those rapid color shifts? I just want to make sure the hardware won't get messed up if the power isn't perfectly constant during quick fades.

I think the absolute declaration that a dedicated constant current driver is the only way to go overcomplicates the matter. It seems like you're overstating the difficulty of keeping the current stable. If you choose a high-quality buck converter with robust feedback mechanisms, you can actually dial in a very precise current limit and it will stay stable under load. Most of these power modules are engineered to maintain that specific output, and saying a manual adjustment on a converter is a 'massive risk' feels like a bit of an exaggeration for what is essentially an electrical tuning job.

I've been looking at some simpler power setups for my own light projects, and the difference between a buck converter and a dedicated driver is confusing. It sounds like you are worried about the light burning out too fast, which is fair. For my own addressable lights that are mostly just blinking and changing color, maybe the stable power isn't as much of a deal as keeping the device cool. It makes sense that the heat has to go somewhere. If I use one of these drivers, is the most important part making sure the driver itself stays cool, or is it just the chip it is powering?

Honestly, the arguement over dedicated drivers versus a good buck converter felt like spinning my wheels til I actualy tested it out on a small setup. I was worried about the ripple and stability, but the theory is hard to trust until you see the numbers. What made the difference for me was just grabbing a digital multimeter with the clamp function. I used it to measure the real current draw across the load while ramping up the voltage, which quickly showed me how much the supply fluctuated before I gave up on the cheap module. It just confirmed the higher quality units are neccessary for a reason.

Update: went with the constant current driver like the first reply suggested. My electrician friend said the same thing, and after reading the debate here I decided not to gamble with a converter that had a vague amps rating. Got it wired up last weekend and the chip is running cool on the CPU cooler, no drama at all. Basement finally has a fake sun.