Creating a Pixel LED using WS2811 IC

The WS2811 is a 3 channel output IC specially designed for pixel LEDs .It includes an intelligent digital data latch port and a signal reshaping and amplification circuit.It also have a precision internal oscillator and  a 12V voltage programmable constant current output drive circuitry.To reduce the power supply  noise , the 3 output channels designed with delay turn-on function.   

 

How It Works

This IC uses single line NZR (Non Return to Zero) communication  method .After the chip power-on  reset event, the Data IN port receives data from the controller, the first IC collects initial 24bit data then sends the internal data to the latch, the other data which reshaped by the internal signal reshaping and amplification circuit will be sent to the next IC through the data out  port.This IC adopts auto reshaping transmit technology ,making the chip cascade number is only depend on the speed of signal transmission.

All chips synchronously send the received data to each  segment when the Data in pin receives a reset signal.It will receive new data again After the reset signal finished.Before a  new reset signal receive, the control signal of OUTR ,OUTG,OUTB port will remain unchanged. IC sent PWM data to OUTR,OUTG,OUTB ports which will set the RGB voltages of the pixel LED connected to it. 

Features of WS2811 IC

• 12v output port compression.
• Built in voltage stabilizer.
• Adjustable 256 Gray level.
• Built in signal reshaping circuit.
• Built-in electric reset circuit and power lost reset circuit.
• Cascading port transmission signal by single line.
• Signal distance up to 10m without using any additional circuitry.
• Send data at speeds of up to 400 Kbps and 800Kbps in two modes.

The Circuit Diagram

WS2811 Diagram 5v

In this circuit use we use 5v supply which gives constant current output about 18.5mA at each output pin , the advantage of this is that the pixel LED can retain it's luminescence and color temperature due to constant current drain through output pins of the IC .The 104(0.1uf) non-polarize capacitor work as a bypass capacitor to ground any AC components in the power rail , Two 33ohm resistors are connected at the data input or output port to match the impedance (Optional). In this circuit we have used a common Anode RGB LED .

WS2811 Diagram 12v

In this circuit arrangement multiple RGB LEDs being used in series with a 12v supply which gives constant current output about 18.5mA at each output pin. In order to reduce the effects of power noise and to drop the voltage at VDD pin of the IC a 1.2Kohm resistor in series with the (VDD) pin is being used.The 104(0.1uf) non-polarized capacitor work as a bypass capacitor to ground any AC components in the power rail , Two 33ohm resistors are connected at the data input and the output port to match the impedance (Optional). R4 at OUT R pin is a voltage divider The value of that resister can be measured by using the V= I x R equation. In this case R = V/ I . V in this case voltage across the R resister which can be measured by Vs - Vled (supply voltage - Voltage across the R leds which can be measured using a multi meter ) .Since "I" is constant at 18.5mA,  Finally we can come to a equation 

R = Vs -Vled / 18.5mA.

 Designing Pixel LED PCB

For the PCB we have two designs one is using through hole components and the other is using SMD components. If you don't have any worries about the size of the PCB you can choose the PCB with through hole components. If you have any concern about the size of the PCB you can choose the PCB with SMD components.

WS2811 Through Hole PCB

WS2811 Pixel LED PCB 5V

 

• D1 - For common Anode RGB LED  

• J1  - In connector (Data IN,Gnd,V+)

• J2  - OUT connector (V+,Gnd,Data OUT)

• U2 - WS2811 IC (DIP08)

• R1 , R2 ,R3 - 100Ohm , 33 Ohm ,33Ohm (1/4W)

• C1 - 0.1uf (Ceramic Non-polarized)
 

This PCB is 32mm X 23 mm (WxH) designed only using Through hole components .The IC package in this case DIP8 . Two 3pin connector headers being used for the input and output connections (J1,J2). The resisters (R1,R2,R3) are 0.25 watt . Use the D1 port for the RGB LED connection.If you are using a 5v supply R1 resistor is not required , short the R1 pins if you are using a 5v supply. 

• How to use the pdf layout File -.The pdf file consist of two pages first page is the bottom copper side layout and the second page is the top silk layout . Simply print the file (select scaling settings as non in the print settings ) . Use the screen UV- paint method or Heat paper transfer method . Use the Grabber files if you want the PCB to be manufactured by a PCB manufacturer. 

[ Download the pdf layout File ]

[ Download the Proteus Project and Gerber Files ]

WS2811 SMD PCB 5v I

WS2811_Pixel_LED_PCB_SMD_5V

 

• D1 - For common Anode RGB LED 

• J1  - In connector (Data IN,Gnd,V+)

• J2  - OUT connector (V+,Gnd,Data OUT)

• U2 - WS2811 IC (SOP8) 

• R1 , R2 ,R3 - 100Ohm(1206) , 33 Ohm (0805),33Ohm(0805)

• C1 - 0.1uf (0805)

This is a 2 layer PCB designed to save the space as much as possible . It's a 20mm x 15mm PCB designed only using SMD components .The WS2811 IC package used is SOP8 .SMD pads are being used for the input , output and RGB LED connections. The R2 and R3 resistors are SMD 0805 package which are 0.1w resistors but the resistor used for the R1 is SMD 1206 package which is not required if you are using 5v power supply.short the R1 SMD pads if you are using a 5v supply.

[ Download the Proteus Project and Gerber Files ]

WS2811 SMD PCB 5v II

WS2811 SMD PCB 5v

This is a 2 layer PCB. Designed  to absolute minimum dimensions and minimum components . It's a 12mm x 19mm PCB designed only using SMD components .The WS2811 IC package used is SOP8 . SMD pads are being used for the input , output and RGB LED connections.Use the Grabber files if you wants the PCB to be manufactured by a PCB manufacturer. 

 [ Download the Proteus Project and Gerber Files ]

 

 5050 RGB Pixel LED PCB with WS2811 IC

5050 RGB LED Pixel LED PCB

 

This is a 21mm X 7mm (WxH) PCB can be used as pixel LED strip or string by soldering one PCB to another side to side . This PCB uses 5050 package SMD RGB LED (D1). The WS2811 IC package used is SOP8 .SMD pads are being used for the input , output. The R2 and R3 (33Ohm)resistors are SMD 0805 package which are 0.1w resistors.C1 is 0.1uf  0805 package SMD capacitor.

[ Download the Proteus Project and Gerber Files ]

 How to use the WS2811 Pixel LED Unit 

Now we have created our WS2811 pixel LED PCB , Lets see how to use it. These units connects in series . The amount of units in series depends on the amount of the pixel LED units supported by the pixel LED controller or the microcontroller.

WS2811 Pixel LED Wiring Diagram

As you can see the first pixel LED unit connects to the controller .The controller data OUT terminal connects to the data IN of the pixel LED unit . The ground and the +5 terminals of the controller connects to the GND and the +5 pad of the pixel LED unit respectively. At the other end , The data OUT pad of the 1st pixel LED unit connects to the data IN of  the next pixel LED unit .The GND and +5 pads of the pixel LED unit connects to the GND and +5 pads of the next unit respectively.

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