Constant Current vs Constant Voltage LED Modules

This article mainly discusses the constant voltage and constant current of the 3-LED 12V module.

waterproof led module

What is discussed here is not the constant current and constant voltage of the power supply, but the current and voltage of the module itself.

Test the constant voltage module and constant current module separately and you will understand. Watch the video below.

Constant voltage module video

After watching the video, you will find that the higher the voltage, the current will continue to rise, and the current will continue to rise until it is greater than the rated current of the LED bead itself. When the rated current of the LED bead is exceeded, the LED bead will burn out.

So For this kind of module, a stable voltage output power supply is required. Only when the power supply outputs a stable 12V, can the module work stably. And this is the cheapest option. This is its advantage, it is usable and cheap.

However, this module also has its shortcomings, which are mainly reflected in the following 3 aspects:

  • For this kind of module, one or more resistors must be connected in series and in parallel to consume the voltage difference after the LED voltage is divided. What does this mean? For example, if the power supply output is 12V, then the voltage of three LEDs connected in series cannot exceed 12V. If it exceeds 12V, the 12V of the power supply cannot light up the lamp beads, and the voltage must be divided by resistors. The resistor is equivalent to the load and will generate heat. When working for a long time, the resistor will heat up. When the resistor heats up, it will cause excessive current. The current here is also the current of the LED lamp bead. Long-term use of high current in the lamp bead will cause light damage. Brightness decreases. Therefore, in this kind of module, there is also a good heat dissipation design and the use of high-current lamp beads, so as to extend the service life of the LED. Now you can see we use 2 resistors in this module.
12V cc led module
  • If 20, 25, or even 50 modules are connected in parallel, the working voltage of the first module will be different from that of the last module due to the low voltage of 12V. Because such a long wire also acts as a resistor and consumes voltage. Therefore, if the wires used in the modules designed by some manufacturers are not good enough, the voltage difference between the first module and the last module will be relatively large, resulting in different brightness. The simplest solution is to use enough copper wire to reduce the voltage at the beginning and end.
  • Since this module is driven by a 12V power supply, the output ripple of the 12V power supply on the market is different, causing the LED module to work unstable. The following tests the output waveform of a 24V power supply.
24v output ripple

Since I couldn’t find a 12V power supply for the time being, I used a 24V power supply instead. You can see the 24V power supply through the oscilloscope, and the maximum output is 24.71V. If a load is connected for a moment, the voltage can rise to 40V, which we call peak voltage. From the above video, we can imagine that the impact of high voltage will also impact the current. Therefore, if the module works for a long time, the brightness will dim or the lamp will burn out.

To sum up, ordinary constant voltage modules are cheap, but have shortcomings. They need stable 12V output and good heat dissipation.

Next, learn the constant current module

This is a constant current module. As you can see from the video, when the power supply output voltage exceeds 12V, even if it reaches 18V, the LED operating current is still constant, which ensures that the lamp beads will not burn out due to overcurrent.

Therefore, by comparing constant voltage modules, constant current modules have the following advantages:

  • Just need the power supply to provide enough current
  • The working current of the lamp bead is always controlled at the current we designed, ensuring that the lamp bead chip will not burn out due to large current.
  • It can ensure that the brightness of the head and tail lamp beads is consistent.

If combined with good heat dissipation design, the life of the constant current module will be longer.

The disadvantage is that constant current modules require more electronic components and chips, so the cost is higher.

Both types of modules exist in advertising light boxes, and customers can choose the appropriate module according to the different quality requirements of end customers.

Generally speaking.Small modules have high current and high power, and it is recommended to use a constant current solution.