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What is a Constant Voltage LED Driver?
The answer is quite simple: An LED driver allows the output current to fluctuate to maintain a constant voltage output to your LEDs.
There are two types of LED drivers: Constant Voltage and Constant Current.
The type of LED driver you need to use depends on how the LED manufacturer has designed their LED strip or LED lights.
Constant Voltage LED circuit designs
Low-cost LED strips and lights are usually built with a simple design. Power is supplied to the LED strings from a constant-voltage LED driver, and a resistor is used on each string of LEDs to limit the current (as shown in the diagram), avoiding damage to the LEDs if too much current is supplied.
Although this design is low-complexity and low-cost, it has poor current regulation and low efficiency.
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If an LED within a string fails or draws more current than it should, this will cause an imbalance in the circuit, adversely affecting the LED light's performance.
Manufacturers of quality constant-voltage LED lighting products will use a better design incorporating a constant-current LED driver IC to supply the power to each string (see diagram).
This design ensures that the optimum current is delivered to each LED string for maximum efficiency. It is also able to cope with a single LED failure, as the constant current LED driver IC will detect the imbalance in the circuit and adjust its output accordingly.
Naturally, it is more expensive to manufacture constant-voltage LED products using this design, which is why different LED strip prices vary.
The incoming voltage must remain constant for both of the above designs to work correctly.
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This is where the constant-voltage LED driver comes in. It incorporates circuitry to ensure that the voltage supplied to the LED strip or light fitting remains constant, regardless of any fluctuations in the AC power being delivered from the wall socket.
Achieving this allows the current to fluctuate.
Let’s take a look at how current and voltage relate to each other in LED drivers.
A 150-watt 12V constant voltage LED driver normally delivers the 12V at 12.5 Amps.
To calculate an LED driver's power output (Watts), you multiply the voltage by the current.
So, 12V x 12.5 Amps = 150 Watts (12 x 12.5 = 150).
If we had a 150-watt 24V constant voltage LED driver, it would deliver the 24V at 6.25 Amps.
24V x 6.25 Amps = 150 Watts (24 x 6.25 = 150).
So you can see there is a relationship between the current and voltage, when determining the power (Watts) in a circuit.
If the incoming AC power supply fluctuates, this will affect the DC output supplied to the LED light strip or fitting. As the voltage must remain constant, the LED driver will allow the current to fluctuate accordingly so that it can compensate for the fluctuations in the incoming AC power and maintain the required constant voltage output.
If you need a constant-voltage LED driver, we invite you to browse the range of LED products shown on this website. If you cannot find a suitable model, please do not hesitate to contact Power Supplies Australia. We will only be too happy to advise you which model is best suited to your particular application.
