Smart LED with Integrated Driver Chip
LEDs come in lots of different shapes and sizes. For Analog LEDs, where the whole strip becomes a single color, choice is mostly about the size, wattage and density of the strip. For Digital LEDs it’s also important to make sure you get the correct chip inside of the LED strip so that you can also control it. Using this chip a Digital LED strip can control each individual LED on the strip and give them all different colors making effects and all sorts of cool displays possible.
This article isn’t meant as a buyers guide but more an information guide. For the buying guide check this article for LED strip or this article for different forms factors!
LED Voltage (5V vs 12C)
I want to start off with talking about LED voltage. For the longest time all addressable LEDs and strips used 5v. This is still the mainly used voltage but newer 12v variants have started to appear. The higher voltage is good for preventing voltage drop over the copper PCB traces for longer distances or higher power draw. This is also the main advantage of choosing these strips. For instance, 144LED/m strip is often found up 1 meter in length but you can get 2m length 12v versions. The reason for this is that the voltage drop with 5v over 1m is so high already you shouldn’t use longer lengths without again injecting extra power at those 1m junctions. Since 12v is a much higher voltage the strip can be double the length before encountering the same issue.
So for projects where you are either going to have long wires from the controller to the LEDs or long amounts of strip and injecting voltage every 100 LEDs is a challenge, 12v strips can be a better choice then standard 5v versions. But as I said, not everything is available yet in 12v and a lot of controllers “asumme” 5v so be careful with this when buying, all of your components, including your controller need to support 12v.
Clockless vs SPI
LED chips basically come in 2 variants, clockless like the well known ws2812b or SPI like the APA102 . Clockless has the advantage of only using a single wire for it’s signaling thus making a whole strip a 3 wire affair. But SPI has the advantage that it’s a lot easier to drive in regards to timing and often can also be driven as much higher data rates for higher refresh speeds or being able to use more LEDs on a single strip. Most generally used LED chips are of the clockless variant, in the below summary I will include which are SPI based and thus need 4 wires instead of 3.
5V LED Chips
The following list is in order of popularity or quantities sold, not actual chronological order. The one’s listed below also certainly aren’t the only chips available on the market, but the most prominent one’s!
The most well known chip currently is the ws2812b chip. This chip become very famous partly because Adafruit gave it the name “Neopixels” and made it available to the general public a few years ago. They also did a lot of work in creating easy to use libraries for Arduino based controllers. A big advantage of this LED chip compared to its predecessors is that this chip houses all the parts needed inside of the actual LED chip itself. Since the introduction they have quickly become the most affordable LED chip and is readily available from lots of sources on Aliexpress and Amazon for cheaper prices then Adafruit tends to sell them. Quality wise there isn’t too much of a difference since all LED strips and LEDs are manufactured by only a handful of manufacturers around the world.
- 3 wire LED strip
Another chip that was made “famous” by Adafruit. Although the ws2812b chips are great for a lot of applications they have a relatively low PWM frequency making them unsuited for particular needs. This is where the APA102 comes in, where the ws2812b, depending on version, runs at 400Hz to 1.6kHz the APA102 chip runs at ~20kHz. It also isn’t a clockless chip with only three wires (+, -, data) but instead uses a 4 wire protocol (+, -, clock, data). That means it’s easier to drive for most microcontrollers but can also be driven a lot “harder” then the ws2812b chip can. This makes it possible to persistence of vision applications and other things the ws2812b is unsuited for. The APA102 also has some advantages in regards to settable brightness and tunable color spectrums. So while more expensive, the APA102 can deliver in some areas where the ws2812b cannot. The APA102 can also be bought in full white variants giving you for instance warm white addressable LED strips.
- 4 wire LED strip
A new competitor from the last 2 years or so. This chip is 100% compatible with the ws2812b and is basically a clone of it. It does however introduce interesting features such as RGBW support by adding an extra dedicated white LED for this inside of the package. Not all software supports this but if it does it does enable a whole new color pallete by mixing all the colors + white. This chip runs PWM at about 1.1kHz making it better in the regard to the ws2812b too.
- 3 wire LED strip
12V LED Chips
As mentioned above, sometimes it’s smarter to choose a 12v LED strip then a 5v one (which are more common). Below are the most commonly used 12v LED strips, again, not in chronological order!
A new chip from the creators of the ws2812b and compatible with the same protocol. Main improvements are a higher internal PWM frequency (around 2kHz but some datasheets also state 8kHz), 12v compatible (5v logic signal) and dual signal wires so that if a chip gets damaged the signal should still reach all other chips.
- 4 wire LED strip
A new contender in the Digitally Addressable LED chip market. This chip is 12v compatible, has dual data lines for redundancy purposes and a unique feature where if you do not provide a data signal it will start playing a test pattern on all the LEDs. It features a global 8kHz PWM frequency with constant current drivers per color make it a lot better flicker wise then other strips. If you don’t send any data to the strip it will go into a test mode displaying various patterns, this stops once a data signal is detected. The data signal is ws2812b (clockless) compatible.
- 4 wire LED strip
- Test pattern when no signal is detected