TM1803 is a 3 output RGB LED drive IC which consist of MCU digital interface, latch , signal reshape and high voltage driver circuits.Through networking ,it can achieve outdoor large-screen and color dot-matrix control . It can support up to 24v RGB LED drive circuits .TM1803 supports up to 256 level gray control.It has a Built-in RC oscillator, signal clock synchronization. While accepting the completed data of this module, data can be auto-shaped and transmitted to next chip through data output pin.
How It Works
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| TM1803 pixel LED block diagram |
This
IC uses single line NZR (Non Return to Zero) communication method
. The data IN pin 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 circuit will be sent to the
next IC through the data out pin.
All chips synchronously send the received data to each segment .When the data IN pin receives a reset signal , It's ready to receive new data again .Before the next new reset signal . IC sent PWM signal to OUTR,OUTG,OUTB FET transistor gates inside the IC. which will set the RGB voltages of the pixel LEDs connected to it.
Features of TM1803 IC
• CMOS Technology.
• Output voltage up to 24V .
• 256 Level Brightness adjustment circuit.
• Serial-shift and cascade Interface.
• Built-in RC oscillator. signal clock synchronization.
• Built-in power-on reset circuit.
• PWM control.
• Single line data Transmission.
• High speed and Low speed modes.
• 80mA maximum output current.
• Data transmission speed up to 800Kbps.
The Circuit Diagram
TM1803 Circuit Diagram 5V
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| TM1803 Pixel LED Circuit Diagram 5v |
In this circuit use we use 5v supply. The 104 (0.1uf) non-polarize capacitor.It work as a bypass capacitor to ground any AC components in the power rail , Two resistors (R2,R3) are connected at the data input or output pins to match the impedance (Optional) ,You can use a resistor between 100Ohm - 200Ohm.
TM1803 Circuit Diagram High voltage
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| TM1803 Pixel LED Circuit Diagram high voltage |
In this circuit diagram the supply voltage is grater than 5v (6v-24v).In order to protect the IC from higher supply voltages a resistor (R1)
in
series with the (VDD) pin is being used .The value of that resistor can
be calculated using the below equation .( If your power supply is 5v This
resistor is not necessary).
R1 = VR1 / I
Where "VR1" is [ Vs (supply voltage) - 5v ] and "I" equals 3mA . eg - If the supply voltage is 6v the R1 value should be 330Ohm , if the supply voltage is 9v the R1 value should be 1.2KOhm .Here is a list of resistor values for different supply voltage levels.
 |
| R1 Resistor values for TM1803 IC |
The 104 (0.1uf) non-polarize capacitor.It work as a bypass capacitor to ground any AC components in the power rail , Two resistors (R2,R3) are connected at the data input or output pins to match the impedance (Optional) You can use a resistor between 100Ohm - 200Ohm. R4 , R5 and R5 are voltage regulate resistors .Their values can be calculated using this equation .
Rled = VRled / Iled
Rled in this case the resistor value .Iled is the current flow through the LED. VRled In this case Voltage drop between resistor pins which is [ Vs - Vled ] (Vled means the voltage drop between LED's anode and cathode). These values can be measured using a multi-meter or referring the datasheets of the RGB LED.As you can see in the diagram , you can use multiple LEDs in series with TM1803 pixel LED IC.
Designing Pixel LED PCB
For the PCB we have two designs one is for 5v and other is for higher voltages (6v-24v) .In order to save the space, the PCBs are designed with only using surface mounted (SMD) components .
TM1803 SMD PCB 5v
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| TM1803 PCB 5V |
• U1 - TM1803 IC / TM1804 IC(SOP8)
• R2 ,R3 - 0.1 W (8050)
• C1 - 0.1uf (Ceramic Non-polarized 1206 )
This PCB is 11.5mm X 20 mm (WxH). Designed only using SMD components .The IC package is SOP8 .The resisters (R2,R3) are 0.1 watt 8050 package. SMD pads are being used for the input , output and RGB LED connections.Use the Gerber files if you wants the PCB to be manufactured by a PCB manufacturer.
[ Download the Proteus Project and Gerber Files ]
TM1803 SMD PCB High Voltage
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| TM1803 PCB High voltage |
• U1 - TM1803 IC/ TM1804 IC (SOP8)
• R1, R4,R5,R6 - 0.125 W (1206)
• R2 ,R3 - 0.1 W (8050)
• C1 - 0.1uf (Ceramic Non-polarized 1206 )
How to use the WS2811 Pixel LED Unit
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.
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| TM1803 Pixel LED Wiring Diagram |
As
you can see to make it easy to understand , the top and bottom sides of the pixel LED units displayed separately . At the top side of the PCB we have the input terminals and at the bottom side we have the output terminals. first pixel LED unit connects to the controller .The
controller data OUT terminal connects to the data IN of the pixel LED
unit which is in the top side of the PCB .
The ground and the +5 terminals of the controller connects to the
GND and the +5 pad of the pixel
LED unit (TOP side) respectively. At the bottom side of the same unit , The data OUT pad of the pixel LED unit connects to the data IN (which is in the top Side) of the next pixel LED unit .The
GND and +5 pads (Bottom side) of the pixel LED unit connects to the GND and +5 (Top side)pads of the next unit respectively.
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