The different of each Pixel LEDs

Publish: 2020-05-13  Views: 61

  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 Pixel 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 Pixel 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.

LED voltage (5v vs 12v)
  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.(But one new 4wires 5V Pixel LEDs named NS107S, also can be 2m, unbelieveble, we will talk about it on next time)

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 it also has it’s downsides, because of the higher voltage a lot of power needs to dissipated to make it run. That means a 12v LED strip will consume more power for running the same effect a 12v will require. Also a lot of controllers “asumme” 5v so be careful with this when buying, all of your components, including your controller need to support 12v.

Clock-less vs SPI
LED chips basically come in 2 variants, clock-less like the well known ws2812b/sk6812 (neopixel) or SPI like the APA102 (dotstars). 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!

ws2812b
The most well known chip currently is the ws2812b chip. This chip became 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 between vendors since all LED strips and LEDs are manufactured by only a handful of manufacturers around the world.

ws2813

A new type from creators of the ws2812b and compatible with same protocol. Main improvements are higher internal PWM refresh rate ( around 2Khz but some datasheets also state 8Khz), 5v compatible and dual signal wires so that if one leds get damaged, the signal should still transfer to all other chips. (almost same with ws2815, but voltage different)

SK6812
A new competitor from the last 3 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 enables a whole new color pallet by mixing all the colors + white. This chip runs PWM at about 1.2kHz making it better in the regard to the ws2812b too, and Adafruit used it same with ws2812b.

ws2811
A chip that was released before the ws2812b series we just talked about. LED strips with this variant use an external chip that controlled the connected LEDs. Most of these have been replaced by the ws2812b variant because it’s easier to integrate into a product but where size isn’t so much a limitation or another type of LED is desired then a surface mount one the ws2811 chip is still used. For instance Christmas light style LEDs still often use the ws2811 because they use a different LED and the larger form factor of the chip isn’t a problem in that application. An advantage of the ws2811 is that it can also be used with 12v power (in certain configurations) but mindful though, sometimes those are only addressable per 3 pixels on the strip in stead of 1. also can be 5v, one pixel one LEDs, for some special application.

APA102 (SPI)
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 do persistence of vision applications and other things the ws2812b is unsuited for. The APA102 also has some advantages in regards to settable brightness and tune-able color spectrums. So while more expensive, the APA102 can deliver in some areas where the ws2812b cannot. Depending on vendor and strip, APA102 is also the brightest LED strip before, so if you need a lot of light output, this might be your LED chip! The APA102 can also be bought in full white variants giving you for instance warm white addressable LED strips.

NS107S (SPI)
A new competitor of APA102, this chip is also 100% compatible with the APA102, but it is not clone, it should be upgrade i think. Higher PWM refresh 27Khz, lower votlage drop (for example, 5m 30leds APA102, each 2.5m need power injection, but 5m 30leds NS107S, no need, just one side connect with the power, it is more convenient for installation.), the brightness is also higher, and white color 3000k 4000k 6000k LED chip are options, i think this is the best 4wires pixel LED chip which include clock wire, and top quality digital led smd, i installed around 10,000meters 30leds NS107S led strip, without any one failured LEDs. (NS107S has 16bit 65536 type, named NS108, more suitable to make led display)

APA107 (SPI)
The old type of NS107S,  PWM refresh rate 9Khz, higher competitive. If you don't need high PWM, so you can choose APA107, also 100% compatible with the APA102.

SK9822 (SPI)
A clone of APA102, but failed clone product, 1.2Khz PWM refresh rate, no advantage just cheap. I suggest APA107 if need cheap type, it is better.

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!

ws2815
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. The downside of running 12v is that it often needs to “burn off” power depending on what is being displayed. This causes ws2815 to use more watts then a ws2812b running the same pattern.

ws2811
Yes, this one is also mentioned in the 5v category. But since the ws2811 is often used in different form factors some of these can be fed with 12v instead of 5v and driving 3 LEDs with the same signal. This for instance makes for very cheap LED strip that runs at 12v, but uses clusters of 3 LED modules which will display the same colors. So even those these are being sold as 60LEDs/m strip, you can only set the color per 3 LEDs not for each single one!

NS8808
A new contender in the Digitally Addressable LED chip market, Original factory is Newstar. 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.

DMX512 IC
If we adopt DMX512 IC for led strips, voltage can be 5v(one pixel one LEDs), 12V( 3leds with one pixel), 24V (6leds with one pixel), led strip color can be white, cct adjustable, rgb, rgbw and rgbcct, widely applcaiton.