Mean Well

MEAN WELL LED Driver Power Supplies

Constant Current and Constant Voltage LED Lighting Solutions

Mean Well LED Driver Power Supplies

Light emitting diodes (LEDs) require drivers for two specific purposes that allow the LEDs to work efficiently and to increase their mean time between failures (MTBF). Since energy regulations have been expanding, a majority of consumers have associated LEDs with lowering their energy costs as well as a longer life-span for the LED as opposed to using traditional incandescent bulbs. For these products to operate, they require an LED driver, which is similar to transformers or ballasts.

Transformers are used with low-voltage bulbs and ballasts were designed for fluorescent lamps. LED drivers are designed specifically to regulate the voltage and current flowing through an LED to keep it at its rated specification. LEDs are usually considered DC devices which is why MEAN WELL LED drivers convert high AC voltage to low DC voltage.

Understanding LED Driver Power Supplies

Features of the MEAN WELL LED Drivers

  • High efficiency and reliability
  • Various protection against shorts, overvoltage, over-temperature
  • Constant Current/Voltage/Power Outputs
  • Safety Regulations
  • Power Factor Correction

Types of LED Drivers

Constant Current Drivers

A majority of constant current LED drivers by MEAN WELL, offer power factor correction (PFC) which is important for any electrical design. Constant current models are beneficial to certain designs where a circuit is created with voltage variance in mind with a load potentially changing over time. While high resistance is a must for these types of power supplies, these designs would be able to withstand high current.

So what would we use a constant current LED power supply for? An example would be lighting for A theatre or a stage where continuous luminosity levels are a necessity. Since all LEDs have a maximum current rating, this would eliminate the issue of having an excess amount of current going through an LED causing extreme heat and failures.

If we were to use a constant voltage driver, it would be more difficult to keep constant lighting since the current would vary within a certain range. Both have their uses depending on the application and what outcome the engineer is trying to accomplish. How the LEDs are placed in the design are not as restrictive since the current will be constant throughout the whole circuit.

Mean Well HLG-60H-C LED Driver Block Diagram
Figure 1 – HLG-60H-C Block Diagram (Source: HLG-60H-C datasheet)

The block diagram (Figure 1) shows the logic of how the LED driver operates. Once an AC input voltage passes through both an electromagnetic interference (emi) filter and rectifiers, it flows through the (PFC) circuit, and power switches from AC voltage to DC voltage. The DC voltage is passed through more rectifiers and a filter and feedback into a detection circuit for PWM and PFC control. They also offer numerous protections against overvoltage, over-temperature, and overload protection for the HLG-60H-C series.

Constant Voltage Driver

Another subset of LED power supplies are the constant voltage versions which as the name suggests, maintains the specified voltage while varying the current depending on the load. Most of the time these drivers are implemented into LED flex strip applications or under-cabinet lighting. However, they can also be used with other categories.

An example is if a strip of LEDs requires 24V to function. Since the known voltage is 24V, we use a current limiter, typically a resistor, to draw the necessary current that the LEDs need to turn it on. The LED strip will work flawlessly since it meets the required voltage and current to maintain the proper brightness.

The types of designs these can be used in are ones that need to maintain a constant voltage output where current is not an issue. By using a current limiter such as a resistor, an engineer can keep the current at a particular value without having the voltage fluctuate.

Constant Power Driver

The final type of LED driver is MEAN WELL’s newly developed constant power driver where within a given voltage and current range, the power output will be consistent. What makes this one special if it is neither constant voltage nor constant current?

Mean Well HLG-60H-C LED Driver Block Diagram
Figure 2 – LDC-80 I-V graph (Source: LDC-80 datasheet)

The graph shows (Figure 2) the vast range of voltage and current that the power supply can output. The output current is 700mA by default unless adjusted using a potentiometer to change the rated current. It can be adjusted between 700mA to 2100mA.

Mean Well HLG-60H-C LED Driver Block Diagram
Figure 3 – LDC-80 Output Current Adjustment with potentiometer (Source: LDC-80 datasheet)

Essentially the constant power LED power supply acts similarly to constant current but with a higher range or voltage while maintaining constant power. The issue with constant current is that once the current is applied to an LED the solder point temperature rises, leading to a dip in voltage. With a constant power LED driver if the voltage starts to decrease the power supply compensates by increasing the current to maintain consistent wattages, allowing the LED to stay within the operating temperature while retaining luminosity.

More About LED Drivers

With all the different types of outputs, there are still many various components that come with these LED drivers. Most of the drivers are either dimming, non-dimming, or DALI. The dimming versions come with three different methods of dimming an LED such as using an additive voltage, PWM signal, or resistance. The DALI version utilizes a push button to dim, by applying a DALI signal to vary the brightness of an LED.


MEAN WELL carries thousands of LED power supply products to provide the power solutions for your lighting applications.

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