Constant Current vs. Constant Voltage: Find the Right LED Power Supply

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     The fact that LEDs are constant current devices does not mean that they require a constant current supply. In some cases, constant voltage power supplies might be best. We'll compare constant current LED drivers and constant voltage LED drivers to help you choose the perfect LED power supply for your application.

      LEDs run on low voltage direct current electricity, but outlets generally provide high voltage alternating current electricity. The main purpose of an LED driver is to convert this higher voltage alternating current into the lower voltage direct current electricity that LEDs are designed to handle.

    LEDs are constant current devices with a forward voltage drop. This means that the supply voltage must be above this drop in order to allow current to flow, and by controlling the current you control the amperage. Too much or too little current can cause the emitted light to vary or degrade at a faster rate due to higher temperatures in the LED. An LED driver responds to the changing needs of an LED circuit by supplying the LED with a constant amount of power (within a rated current range) as its electrical properties change with temperature.

   There are several different types of external LED drivers, but they can be divided into two main types: constant current (CC) drivers and constant voltage (CV) drivers.

   When to use constant current drivers

    A constant current LED driver varies the voltage on the electronic circuit to maintain a constant electrical current. This ensures that regardless of voltage fluctuation, the current conducted to the LED will be maintained at the specified level. Constant current drivers are designed for LEDs that require a fixed output current and voltage range. Constant current drivers typically list their specifications on the device, with a single output current class and voltage range that varies with LED wattage.

    I f you are building your own device or working with high power LEDs, constant current LED drivers are the way to go as they prevent overheating or thermal runaway by never exceeding the maximum current specified for the LED. Designers generally find these drivers easier to control in applications, and they allow for a more consistent level of brightness. Controlling current as opposed to voltage provides more precise control of the power dissipated in the LED and helps designers project failure rates much more accurately than when constant voltage supplies are used.

    When to use constant voltage drivers

    Constant voltage drivers come in a wide variety of forms, from traditional power supplies to enclosed designs, depending on the target application. Constant voltage drivers have a fixed voltage which is typically either 12 Vdc or 24 Vdc. They are used for LEDs that require a stable voltage and have current already regulated either by simple resistors or by an internal constant current driver located inside the LED module.

     If you have already confirmed that your LED or matrix is designed to withstand a certain voltage, constant current LED drivers are generally more intuitive for design engineers, and they are often a cheaper solution compared to constant current drivers. .

     Drive strings of LEDs

    With LEDs connected in a series configuration, the forward voltage drop of each LED in the string is additive. This is why constant current drivers always identify the output voltage range corresponding to their capability. Multiple series-connected LED strings can be placed in parallel and driven by multi-output constant current drivers to limit the drive voltage.

    When many strings of LEDs are used in series, the most efficient way to drive them is a constant current power supply, which connects the LEDs directly to the terminals of the power supply. However, if there are strings connected in parallel, it may be difficult to obtain the current corresponding to all the strings. In this case, an external component is used to control the current, which produces an overall less efficient amount of lumens per watt.

   Constant Current vs. Constant Voltage: Application Examples

        What you choose for your type of LED driver can largely depend on the intended end use as well as other constraints. For signage and other applications that depend on bright or contrasting colors, a constant voltage power supply may be more cost effective and easier to design. Also, color changes tend to be relative and will have minimal impact on perceived light efficacy. Efficiency is also less important in signage, and additional heat dissipation is more economical when the application is a single installation as opposed to lighting distributed across an entire site.

     However, when the intended end use is for lighting, constant current drivers may be a better choice. These allow for more uniform control of light quality and brightness and the systems can be easily tuned to keep the LEDs operating in their most efficient range. LEDs operating in their most efficient range generally require less heat dissipation and the metal of the lighting fixture is usually sufficient to spread the heat and keep the LEDs operating in an ideal and efficient state.

    Understanding the functional differences in driving LEDs with constant current or constant voltage supplies can help a designer optimize their design to meet their goals for light output, light quality, and product longevity. design.

 

     The fact that LEDs are constant current devices does not mean that they require a constant current supply. In some cases, constant voltage power supplies might be best. We'll compare constant current LED drivers and constant voltage LED drivers to help you choose the perfect LED power supply for your application.

      LEDs run on low voltage direct current electricity, but outlets generally provide high voltage alternating current electricity. The main purpose of an LED driver is to convert this higher voltage alternating current into the lower voltage direct current electricity that LEDs are designed to handle.

    LEDs are constant current devices with a forward voltage drop. This means that the supply voltage must be above this drop in order to allow current to flow, and by controlling the current you control the amperage. Too much or too little current can cause the emitted light to vary or degrade at a faster rate due to higher temperatures in the LED. An LED driver responds to the changing needs of an LED circuit by supplying the LED with a constant amount of power (within a rated current range) as its electrical properties change with temperature.

   There are several different types of external LED drivers, but they can be divided into two main types: constant current (CC) drivers and constant voltage (CV) drivers.

   When to use constant current drivers

    A constant current LED driver varies the voltage on the electronic circuit to maintain a constant electrical current. This ensures that regardless of voltage fluctuation, the current conducted to the LED will be maintained at the specified level. Constant current drivers are designed for LEDs that require a fixed output current and voltage range. Constant current drivers typically list their specifications on the device, with a single output current class and voltage range that varies with LED wattage.

    I f you are building your own device or working with high power LEDs, constant current LED drivers are the way to go as they prevent overheating or thermal runaway by never exceeding the maximum current specified for the LED. Designers generally find these drivers easier to control in applications, and they allow for a more consistent level of brightness. Controlling current as opposed to voltage provides more precise control of the power dissipated in the LED and helps designers project failure rates much more accurately than when constant voltage supplies are used.

    When to use constant voltage drivers

    Constant voltage drivers come in a wide variety of forms, from traditional power supplies to enclosed designs, depending on the target application. Constant voltage drivers have a fixed voltage which is typically either 12 Vdc or 24 Vdc. They are used for LEDs that require a stable voltage and have current already regulated either by simple resistors or by an internal constant current driver located inside the LED module.

     If you have already confirmed that your LED or matrix is designed to withstand a certain voltage, constant current LED drivers are generally more intuitive for design engineers, and they are often a cheaper solution compared to constant current drivers. .

     Drive strings of LEDs

    With LEDs connected in a series configuration, the forward voltage drop of each LED in the string is additive. This is why constant current drivers always identify the output voltage range corresponding to their capability. Multiple series-connected LED strings can be placed in parallel and driven by multi-output constant current drivers to limit the drive voltage.

    When many strings of LEDs are used in series, the most efficient way to drive them is a constant current power supply, which connects the LEDs directly to the terminals of the power supply. However, if there are strings connected in parallel, it may be difficult to obtain the current corresponding to all the strings. In this case, an external component is used to control the current, which produces an overall less efficient amount of lumens per watt.

   Constant Current vs. Constant Voltage: Application Examples

        What you choose for your type of LED driver can largely depend on the intended end use as well as other constraints. For signage and other applications that depend on bright or contrasting colors, a constant voltage power supply may be more cost effective and easier to design. Also, color changes tend to be relative and will have minimal impact on perceived light efficacy. Efficiency is also less important in signage, and additional heat dissipation is more economical when the application is a single installation as opposed to lighting distributed across an entire site.

     However, when the intended end use is for lighting, constant current drivers may be a better choice. These allow for more uniform control of light quality and brightness and the systems can be easily tuned to keep the LEDs operating in their most efficient range. LEDs operating in their most efficient range generally require less heat dissipation and the metal of the lighting fixture is usually sufficient to spread the heat and keep the LEDs operating in an ideal and efficient state.

    Understanding the functional differences in driving LEDs with constant current or constant voltage supplies can help a designer optimize their design to meet their goals for light output, light quality, and product longevity. design.