Addressable Pixel LED Tape: Choosing Between SK6812, WS2815 and HD108

Most specifications for addressable pixel LED tape start with a chip name. That order is usually wrong. The chip family decides protocol and colour depth, while the supply voltage decides how the run is built, where power is injected, and how much copper the project pays for. A contractor who fixes voltage and run length first will find that only one or two IC families actually fit the drawing.

This guide sets out the decision order we use with signage makers and lighting contractors, followed by the signal checks that prevent the most common field failures.

Voltage comes before the chip

The physical limit on any pixel run is voltage drop in the copper. Every addressable tape carries the same supply along thin conductors, and the voltage at the far end falls as current rises. The practical result is that 5V products need short runs and frequent injection, while 12V reduces current to roughly a third at the same output power, which pushes the first injection point out by about the same factor.

At 60 LEDs per metre, a 5V run of 5 metres normally needs power fed at both ends. The same density at 12V can usually span three times that distance before the next feed. For coves, facades and long linear runs above 24V, the tape uses an external IC with on-board regulation, driven by SPI or DMX512, which keeps current low enough that a single feed covers a storey.

That is why voltage selection is a cost decision as much as a technical one. Fewer injection points mean less cable, fewer power supplies and less labour on site, and those three items often outweigh the price difference between IC families.

SK6812: a dedicated white channel at 5V

SK6812 is the family to specify when colour quality includes white. It runs on a single data line at 800 kbps and is available in RGBW versions with a separate white die, so neutral white is produced by a white emitter rather than by mixing red, green and blue.

For retail interiors, museums and showrooms where a specification calls for Ra90 and above, that fourth channel removes the metamerism problem that RGB mixing creates under different light sources. Colour temperature also stays stable as brightness changes, because the white channel is dimmed directly.

The trade-off is current. A 5V RGBW pixel draws up to 60mA at full output, so a 144 LED/m tape pulls close to 8.6A per metre at full white. Injection planning has to be done before the drawing is issued, not after the first metre is installed. Single-wire data also means each pixel regenerates the signal for the next, so a failed pixel interrupts everything downstream. SK6812 suits accessible installations where a service visit is realistic, and short decorative runs where the white channel earns its cost.

WS2815: 12V with a backup data line

WS2815 addresses the two weaknesses of a 5V single-wire chain. It runs at 12V, so current and injection requirements drop, and it carries a second data line that acts as a backup. If one pixel loses its data path, the redundant line keeps the chain alive behind it.

That behaviour matters on facade lighting, where a single dark pixel at height is a service call with scaffolding. One distributor in Germany specified WS2815 tape for exactly this reason on a building envelope, and the backup path is the argument that closed the project.

The limits are colour and resolution. WS2815 is RGB only, with no white die, and it uses 8-bit grayscale per channel. It is the right answer for long exterior runs, media facades and any installation where access is expensive. It is the wrong answer for a project that needs high-CRI white or smooth low-level dimming on camera.

HD108: 16-bit grayscale for camera-facing work

HD108 uses 16-bit PWM per channel, which gives 65,536 steps instead of the 256 of an 8-bit IC. On a wall at full brightness the difference is invisible. At 1% output, or through a camera at a shallow exposure, 8-bit control shows visible stepping and colour banding, and 16-bit does not.

The interface is clocked: data and clock travel on separate lines, which is more tolerant of timing than a single-wire protocol but less tolerant of cable length. HD108 also runs at 5V and expects 5V logic, so a 3.3V controller needs level shifting. These tapes are the usual choice for video walls, broadcast sets, stage backdrops and architectural features that will be photographed. Where the control system is DMX512 rather than SPI, the same pixel chips can be supplied on a DMX512 tape with the addressing handled at the driver.

Signal debugging in the order that finds faults

The first check is common ground. Controller and tape must share a ground at the injection point, and the ground conductor should match the data conductor in gauge. A missing or thin ground shows up as random colour shifts that change when the installation is touched, and it is the most frequent cause of "the tape is faulty" returns we investigate.

The second is logic level. Most pixel tape expects a 5V data signal, and most modern controllers output 3.3V. A marginal high level can pass on a bench at room temperature and fail inside a warm enclosure. A level shifter at the controller output removes the variable.

The third is data direction and termination. DIN and DOUT are not interchangeable, and the arrows printed on the tape define the only valid direction. A series resistor of 33 to 100 ohms at the controller output damps reflections on the data line and costs almost nothing.

The fourth is cable length against protocol. Clocked interfaces such as HD108 tolerate shorter runs than single-wire ones, and both degrade when the data cable is routed beside mains. Beyond a few metres, a differential extender or a DMX512 stage is more reliable than thicker cable.

The fifth is the refresh budget. Total pixel count multiplied by protocol timing has to fit the controller’s frame rate. Overloading a controller produces flicker that appears only on camera or only at certain scroll speeds, which is difficult to diagnose after commissioning. Running the full pixel count on the bench before installation settles it in an hour.

Matching the tape to the project

The sequence is short. Fix the run length and voltage, then decide whether white quality or service access drives the choice, then confirm the refresh requirement against the control protocol. SK6812 covers white-critical interiors at 5V, WS2815 covers long exterior runs where access is costly, and HD108 covers anything that will be filmed.

We manufacture these tapes in-house, including the pixel LED chip and driver circuit, and run an ageing test on every reel before packing. Voltage, pixel density, CCT, CRI, jacket colour and connector type can be set from a project drawing, from 5V to 48V with SPI and DMX512 options. Contractors who send the run length, density and control protocol with an inquiry receive a matching configuration rather than a catalogue number.