Do COB LEDs Flicker?

Are you worried that the COB LEDs¹ in your project will flicker? This flicker can cause headaches and ruin a space, reflecting poorly on your work. The key is understanding its true cause.

Yes, all LEDs, including COB, can flicker. Flicker does not come from the COB chip itself, but from its electronic driver. A high-quality driver provides clean power, making flicker invisible. A cheap driver causes noticeable, harmful flicker.

It's a common concern I hear from clients like Shaz, a purchasing manager in the UAE. He needs a reliable product because his reputation depends on it. He knows that flicker² can be a deal-breaker for high-end hospitality or residential projects. The real issue isn't the COB technology, but what powers it. This distinction is crucial for sourcing lighting that performs as promised. When you understand the components, you can ask the right questions and avoid problems down the road. Let's look deeper into what makes a good COB light and how you can ensure your projects are flicker-free.

Are COB lights any good?

You see COB lights praised for their smooth, powerful beam. But are they always the best choice? Investing in the wrong type can lead to poor performance and unhappy clients.

Yes, COB lights are excellent for creating a strong, uniform light source from a small area. This makes them perfect for applications like downlights and spotlights, where you want a clean beam without the multiple shadows created by SMD LEDs.

When I first started in this industry, I was amazed by COB technology. Unlike older SMD (Surface Mounted Device) LEDs that use many small, individual light points, a COB (Chip on Board) light has multiple diodes packaged on a single substrate. This creates one large, intense light source. The result is a beautifully smooth, high-quality light that looks like it's coming from a single point, just like a traditional halogen lamp but far more efficient. However, I quickly learned that not all COB lights are created equal. I've seen clients choose cheaper options only to face issues with color consistency³ and lifespan. A truly "good" COB light is a system. The quality of the chip, the phosphor coating⁴, the heat sink⁵, and especially the driver all work together. If one part is low-quality, the entire fixture suffers. For a professional like Shaz, specifying a COB light means looking beyond the chip itself and examining the quality of the entire assembly.

The Anatomy of a Quality COB Light

The final performance of a COB fixture depends on the synergy of its core components. A failure in one area compromises the entire unit.

Is it normal for my LED lights to flicker?

You install brand new LED lights, but you notice a subtle strobing effect. Is this normal or a sign of a defective product? This uncertainty can make you question your purchase.

Technically, all AC-powered lights have some flicker. But visible or detectable flicker is not normal or acceptable. It points to a low-quality driver that fails to provide smooth, constant power, which can lead to eye fatigue and headaches.

The biggest lie in the lighting industry⁶ is the term "no flicker." In absolute terms, it doesn't exist. LED lights run on DC power, but our buildings provide AC power. The driver's job is to convert AC to DC. A cheap, poorly designed driver does this crudely, creating ripples in the current that cause the LED to dim and brighten very rapidly. This is flicker. A high-quality driver⁷ smooths out these ripples, pushing the flicker frequency so high and the depth so low that it becomes imperceptible to our eyes and cameras. So while some level of fluctuation is inherent, a well-engineered product should make it a complete non-issue. I always tell my clients that if you can perceive flicker in any way, whether with your eyes or your phone camera, the product is subpar. It's a clear sign that the manufacturer cut corners on the most critical component: the driver.

Understanding Flicker: Frequency and Depth

Flicker isn't just a simple yes-or-no issue. Its effect is determined by two main factors: frequency (how fast it flickers) and modulation depth (how extreme the change in light output is).

• Frequency: Measured in Hertz (Hz). Higher frequencies are less noticeable. Flicker below 100 Hz is often visible and very irritating. High-quality drivers aim for frequencies in the thousands of Hertz (kHz).
• Modulation Depth: A percentage that shows the difference between the maximum and minimum light output. A 100% depth means the light is turning completely on and off. A lower percentage is better.

A good light fixture has a very high frequency and a very low modulation depth⁸. Even if the frequency is high, a large depth can still cause issues for light-sensitive individuals or video recording.

How to eliminate LED flicker?

You know flicker is bad for your projects. So how do you get rid of it? You need a reliable strategy to ensure the lights you source are stable and high-quality.

You eliminate LED flicker by choosing fixtures with high-quality, isolated, flicker-free drivers⁹. Never prioritize a cheap price over the driver’s quality. For dimmable systems¹⁰, use compatible, high-quality drivers and dimmers designed to work together to minimize flicker.

The driver is the heart of an LED fixture. It's the "total switch" for flicker. The LED chip¹¹ itself doesn't cause flicker; it's just reacting to the power it receives. I've spent years explaining this to partners. If you want to eliminate flicker, you must focus your attention and budget on the driver. In my experience, about 80% of LED fixture failures are driver-related. A manufacturer can use the best Cree COB chip in the world, but if they pair it with a cheap, non-isolated driver to lower the price, the fixture is destined to fail or perform poorly. Many so-called "eye-care" lamps are the worst offenders. They are marketed with a health-conscious message but are built with the cheapest possible drivers, resulting in terrible flicker that does more harm than good. It's a marketing gimmick that preys on uninformed customers. A truly flicker-free solution starts and ends with a premium driver.

The Driver is the Deciding Factor

To guarantee a flicker-free installation, your purchasing decision must be centered on the driver.

1. Demand Flicker-Free Drivers: When you specify a product, make "flicker-free" a non-negotiable requirement. Ask the supplier for test reports that show the flicker percentage and frequency. Don't just take their word for it.
2. Choose Brand-Name Drivers: Whenever possible, specify drivers from reputable manufacturers like Philips, Osram, Tridonic, or Lifud. These companies have a reputation to protect and invest heavily in engineering and quality control.
3. Beware of Dimming: Dimming is a common cause of increased flicker. Most dimming methods work by rapidly cutting power to the LED, which can dramatically increase flicker depth. If dimming is required, you must use a high-quality dimmable driver that is proven to be compatible with your chosen control system (e.g., Triac, 0-10V, DALI). Always test the fixture and dimmer combination before a large-scale rollout.

How to check if a LED is flickering?

You've received samples for a big project. How can you quickly and reliably check for flicker before placing a large order? You don't want to discover a problem after installation.

The easiest way to check for flicker is with your smartphone camera. Put your camera in slo-mo video mode or simply open the standard camera app and point it at the light. If you see dark bands moving across your screen, the light is flickering.

This simple "smartphone test" is my go-to method for a quick assessment. I've used it in factories, at trade shows, and during client meetings. It’s remarkably effective at revealing the flicker that our eyes might miss but that our brains still perceive, leading to subconscious strain. While it's not a scientific measurement, it’s a powerful red flag. If a light fails this test, I know the driver is low-quality. For my client Shaz, who manages large purchases, a simple test like this can save him from major headaches. He can screen samples on the spot and immediately disqualify suppliers who provide flickering products. For more precise, professional measurements, we use specialized equipment like a spectrometer¹² or an oscilloscope¹³. These tools give us exact data on flicker frequency and modulation depth, which is essential for projects with strict requirements, like TV studios or healthcare facilities.

Flicker Testing Methods

Here's a breakdown of how you can test for flicker, from simple checks to professional analysis.

Conclusion

Ultimately, all LEDs can flicker, but this is controlled by the driver, not the chip. By choosing high-quality drivers, you ensure stable, flicker-free light for any project.