NeoPixel, WS2812, SK6812: what the names actually mean

Ask three people what a NeoPixel is and you will get three answers: a strip, a chip, or an LED. All three are partly right, which is the problem. The name is a brand, and it sits on top of a pile of other names that mean different things.

This post separates the layers, then maps how the main parts relate to each other, so you can tell what you are looking at when a listing says one thing and the datasheet says another.

NeoPixel is a brand#

Adafruit coined "NeoPixel" in December 2012. The part underneath was WorldSemi's WS2812, whose official name is "WS2812 Intelligent Control LED Integrated Light Source", which is not something anyone can put on a product page. Adafruit did not make the silicon. They popularised it, wrote the library, and the name stuck to the whole category.

The catalogue dates this from the first commit of the Adafruit_NeoPixel library on 12 December 2012, and from Adafruit's own retrospective, "NeoPixels: Five Years In", dated exactly five years later. Almost every NeoPixel sold since is a WorldSemi WS2812B or an OPSCO SK6812.

"DotStar" works the same way: Adafruit's name for the APA102 family.

The layers of a name#

When you read a listing, several different kinds of name are stacked together.

The package number is the nominal size in tenths of a millimetre: a 5050 is about 5.0 × 5.0 mm and a 2020 about 2.0 × 2.0 mm. The real outline often differs a little. The datasheet outline of the WS2812B 5050 is 5.4 × 5.0 mm once the pads are counted, and the WS2812B-2020 is 2.2 × 2.0 mm. The smallest part in the catalogue is the SK6805-EC10, 1.1 × 1.1 × 0.33 mm, and the smallest WorldSemi parts are the 1.3 mm WS2812B-1313 and its siblings. (The SK6805 is its own protocol in the catalogue: the digits in the name are the 5 mA drive current.)

The same driver turns up in several packages. The WS2812B family (the WS2812B and WS2812B-V5 protocols) is catalogued in 5050, 4020, 3535, 2427, 2020, 1313 and the through-hole domes. And the same package holds different drivers: a 5050 might be a WS2812B, an SK6812 or an APA104, and you cannot tell by looking.

A letter is not a standard#

The suffix letters are the part most likely to mislead.

• WS2812 is the original, in a six-pin 5050. It is a WS2811 driver bonded into a package with the LEDs. What LCSC sells today as "WS2812" is a four-pin 5050 with V5-style timing, so the bare name no longer tells you the pin count.
• WS2812B is the four-pin revision that took over. The catalogue notes it is cheaper to assemble and adds reverse-polarity protection.
• WS2812C has the same data windows as the WS2812B-V5 and a 5 mA per-channel drive against the WS2812B's 12 mA; it is most visible as the WS2812C-2020. Resellers call it either the economy version or the small-package one, and the WorldSemi sheets say neither.
• WS2812D is the through-hole 5 mm and 8 mm dome, the WS2812D-F5 and WS2812D-F8. WorldSemi's newer D-V6 sheets have their own timing windows, so the catalogue gives them their own protocol.
• WS2812E has four pins on every WorldSemi sheet in the catalogue, the same timing windows as the WS2812B-V5 and a 12.5 mA drive. It exists in 1313, 2020, 2427, 4020, 5050 and a 3.7 × 3.5 mm MINI package.
• -V5 is not a different part at all. It is a silicon revision of the WS2812B, with its own timing, and it has its own post. WorldSemi has since issued V6 and V7 sheets, and V7 raises the drive from 12 mA to 16 mA.

So "B" means a revision, "C" a lower-current version, "D" a dome, and "V5" new silicon under an old name. None of that is a rule, and another manufacturer's letters mean something else: in OPSCO's naming the digits in SK6805 and SK6812 are the drive current, 5 mA and 12 mA.

Same package, different part#

The nastiest naming trap is in the SK6812 line. The SK6812MINI and the SK6812MINI-E share a protocol and almost a name. The MINI is a 3.7 × 3.5 mm part (a 3535) with pins 1 DIN, 2 VDD, 3 DOUT, 4 GND. The MINI-E is a 3.2 × 2.8 mm part with the pin order 1 GND, 2 DIN, 3 VDD, 4 DOUT, and the catalogue treats it as the reverse-mount version, meant to sit on the back of a board and shine through a hole. (The OPSCO sheet itself does not use the words "reverse mount".) Its id says 3228, not 3535: an earlier version of the catalogue gave it the wrong package size.

A board laid out for one will not work with the other. More generally, the "3535" minis come in at least three different pad patterns across WorldSemi and OPSCO, so the package name alone does not tell you the footprint.

Who copies whom#

Addressable LEDs are cloned constantly, and "compatible" covers a wide range of meanings. The catalogue records how strong each claim is rather than saying "compatible" and leaving it there.

The relationships fall into grades, with examples from the data:

• Drop-in. The SK6812 is a drop-in for the WS2812B in 5050: the pads sit in the same places and the bit timings overlap, so WS2812B code usually drives it. (Its reset is longer, though: 80 µs in the 2015 sheet and above 200 µs in the current one, against the old WS2812B sheet's 50 µs.) The APA102C and APA107 are drop-ins for the APA102.
• Near-clone. Close, with caveats. The SK9822 looks like an APA102 but handles global brightness and end frames differently, and the APA104 is a WS2812B workalike whose reset requirements differ (the catalogue has no APA104 datasheet, so how they differ is unverified).
• Protocol-compatible. The same signalling in a different shape. The WS2812 and WS2812B speak the same protocol but have six and four pins respectively. The SK6812 RGBW has identical timing to the SK6812 but four channels, so driving it as RGB shifts colours down the strip.
• Electrically similar. The same style of part, different timing. The UCS1903 is like the WS2811, the SK6822 like the SK6812 (a 1750 ns bit period against 1200 ns), and the PL9823 like the WS2812B, usually with a different colour order.
• Revision. The same part number, different silicon. The V5.

The practical lesson is to treat "WS2812B compatible" in a listing as the start of a question. An example from the catalogue is XL-5050RGBC-2812B, a Xinglight part whose name gives no clue that it is a WS2812B workalike.

How to tell what you have#

1. Count the pins, but do not trust the count alone. Four pins on a 5050 usually means a plain one-wire part. Six means something extra: a clock (APA102), a backup data line (WS2813, WS2815), the 16-bit WS2816, or the old WS2812. But the 4-pin WS2815 variants exist with the backup input dropped.
2. Measure the package. 5050, 3535 and 2020 parts are visibly different sizes, and the table's package glyph is drawn for this.
3. Read the order code, not the trade name. WS2812B and WS2812B-V5 look the same on a shelf.
4. Check pin one. The same pads get different numbers in different datasheet generations (the SK6812's 2015 sheet says 1 VDD, 2 DOUT, 3 VSS, 4 DIN; the current one says 1 GND, 2 DIN, 3 VDD, 4 DOUT for the same four positions), and the MINI-E has a different pin order from the MINI. The part's page has a pinout drawing for exactly this reason.
5. Look it up here. Use the catalogue and filter by package, protocol, channels or supply voltage. The "known as" column lists the trade names a part is sold under.

Why we keep a catalogue#

Because the naming layers do not line up, "which LED is this?" is a real question with a surprisingly slippery answer. A trade name points at a family, a part number points at a die, a package number says nothing about either, and the order code is the only thing that tells you what arrived in the post.

The catalogue models each layer as its own thing, with the clone relationships and their caveats written down. If you find a part that is wrong, missing or misattributed, tell us.