CC DMX Decoder Technology

How constant current DMX decoders drive series strings of power LEDs at a fixed current, dimmed from a DMX512 controller.

LT-858-CC, LT-880-350 and SR-2112B constant current DMX decoders

Overview

What are CC DMX decoders?

A constant current DMX decoder controls LEDs that need a set current rather than a set voltage. It takes the DMX512 signal from the master and power from a DC supply, and drives each output at a fixed current such as 350mA or 700mA.

It suits power LEDs, spots, downlights and wall washers wired as series strings, with no driver of their own. Each channel is dimmed from 0 to 100% with PWM, so the LEDs keep the same colour as they dim. Our range covers 4-channel and 16-channel decoders, with fixed or DIP-selectable current.

DMX512 in, constant current PWM out
4 or 16 channels
350mA, 700mA or 300–1050mA selectable
12–36V or 12–48V DC input
Dimming, CCT, RGB and RGBW control

CC decoders at a glance

Input signal: DMX512, RDM
Output: Constant current PWM
Channels: 4 or 16
Current: 300 to 1050mA
Supply: 12 to 48VDC
Dimming: 0–100%
Addressing: DIP, buttons, RDM
DMX ports: XLR, RJ45, terminal

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The technology

How a CC DMX decoder works

Each output channel has a current regulator. It adjusts the voltage across the LED string so that the current stays at the set value, whatever the number of LEDs, within the decoder's output voltage range.

The decoder reads its channels from the DMX line, starting at its DMX address. Each value from 0 to 255 sets the PWM duty cycle: the regulated current is switched on and off rapidly, and the share of time it is on sets the brightness.

The supply voltage must be higher than the total forward voltage of each LED string, so the regulator has headroom to work.

Simplified illustration: the decoder holds each LED string at its set current and dims it with PWM according to the DMX level.

CC or CV

Constant current or constant voltage?

Choose the decoder type to match how the LEDs are designed to be powered.

Feature	CC DMX decoder	CV DMX decoder
Output	Fixed current, e.g. 350mA	Fixed voltage, 12V or 24V
LED wiring	Series strings	Parallel strip and modules
Typical loads	Power LEDs, spots, downlights, wall washers	LED strip, linear modules
Per channel	300 to 1050mA	3 to 12A
Load limit set by	Output voltage range	Output current rating

See CV DMX decoder technology for 12V and 24V LED strip.

Our range

CC DMX decoders compared

Ratings from each decoder's datasheet.

Decoder	Channels × current	Input / output voltage	Set-up and DMX ports
LT-858-CC	4 × 300–1050mA, max. 176.4W	12–48VDC / 3–42VDC	DIP switches, RDM, RJ45
LT-880-350	16 × 350mA, max. 257.6W	12–48VDC / 3–46VDC	DIP switches, RDM, XLR-3, RJ45, terminal
LT-880-700	16 × 700mA, max. 515.2W	12–48VDC / 3–46VDC	DIP switches, RDM, XLR-3, RJ45, terminal
SR-2112B	4 × 350mA, 4.2–12.6W per channel	12–36VDC	Buttons and digital display, 3 or 4 channels
SR-2114B	4 × 700mA, 8.4–25.2W per channel	12–36VDC	Buttons and digital display, 3 or 4 channels

The LT-880-700 and SR-2114B are covered by the same datasheets as the LT-880-350 and SR-2112B. Ask us about availability.

Benefits

Advantages of CC DMX decoders

Why constant current control suits power LED fittings.

Correct LED current

Each string runs at its rated current, for long life and steady output.

Stable colour

PWM dimming keeps the current constant, so colour does not shift as the LEDs dim.

No extra drivers

Drive power LEDs directly, without a separate driver in each fitting.

Selectable current

The LT-858-CC sets 300 to 1050mA on DIP switches to suit the LEDs.

Many channels

16 outputs on the LT-880 for multi-zone or multi-colour fittings.

RDM

Read and change DMX addresses remotely on the LTECH models.

Selection & set-up

Choosing and setting up a CC DMX decoder

Match the current: choose a decoder or setting that matches the LED's rated current.
Add up the voltage: multiply the LED forward voltage by the number in each string, and keep it within the output voltage range.
Choose the supply: pick a DC supply above the string voltage, within the decoder's input range, sized for all channels.
Set the current first: on the LT-858-CC, set the DIP switches with the power off.
Set the address: use DIP switches, the buttons or an RDM master.
Wire the line: daisy-chain the DMX to each decoder and terminate the last one with 120Ω.

Related technology and products

Complete the system with a master and drivers:

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Max. channels

1050mA

Max. per channel

46V

Max. string voltage

0–100%

Dimming range

Where CC DMX decoders are used

Wherever power LED fittings are controlled from DMX.

Architectural

Facade wall washers and floodlights in RGB or RGBW.

Downlights

Colour-changing and tunable white downlights and spots.

Entertainment

Stage and venue effects on power LED fixtures.

Landscape

Garden, tree and water feature uplighters.

Retail

Display and feature spots on DMX scenes.

OEM fittings

Custom LED fittings built with power LEDs and DMX control.

FAQ

CC DMX decoder questions

A constant current DMX decoder takes a DMX512 signal and power from a DC supply, and drives each output channel at a fixed current, such as 350mA or 700mA. It suits power LEDs and LED modules wired in series strings, rather than 12V or 24V LED strip.

Use a CC decoder when the LEDs need a set current, for example 1W or 3W power LEDs, downlights, spots and wall washers without their own driver. Use a CV decoder for 12V or 24V LED strip and modules, which have their own resistors or current regulators built in.

The LEDs on each channel are wired in series, and their forward voltages add up. The total must sit within the decoder's output voltage range and below the supply voltage. For example, the LT-858-CC gives 3 to 42V from a 48V supply, so about 13 LEDs of 3.2V can run on each channel.

On the LT-858-CC, a set of DIP switches selects the current from 300mA to 1050mA in 50mA steps, set with the power off. The LT-880 and SR-2112B have a fixed current: 350mA on the LT-880-350 and SR-2112B, and 700mA on the LT-880-700 and SR-2114B.

The LT-858-CC and LT-880 use DIP switches 1 to 9, where the address is the sum of the switches turned on, and also support RDM addressing. The SR-2112B uses three buttons and a digital display to set the hundreds, tens and units of the address.

CC DMX Decoder Technology