Constant Voltage and Constant Current Power Supply

Last updated: August 30, 2022 at 17:33 pm

There are many different types of power supplies available on the market. Today we would like to discuss the two main power supplies: constant voltage and constant current.

What is the difference between the constant voltage and constant current power supply? The biggest difference between them is whether the voltage or current is fixed.

What are the Constant Voltage and Constant Current Power Sources?

What is a Power Supply with Constant Voltage?

There is a power circuit called a constant-voltage power supply. This circuit keeps the output voltage at the same level all the time. Therefore, no matter how much current is used by the device, there will never be much change in voltage. Electric appliances will operate more efficiently with consistent power because they can’t work well if the voltage varies much. Therefore, manufacturers must pay careful attention to voltage, affecting their process.

What is a Power Supply with Constant Current?

Constant-current power supplies yet, maintain a fixed output current. That means the current will always keep the same whether the voltage varies. This power supply is always for LED lights with lighting functions.

Advantages of the Constant Voltage Power Adapter and Constant Current Power Supply

We know what they are and how they work now. Let’s discuss the advantages of them as follows.

Constant Voltage Power Adapter

Flexible: Due to the fixed voltage, the user can add as many LEDs as they like, up to the current limit of the LED driver. At the same time, this may result in a reduction in brightness.

Easily Accessible: The constant voltage power supply is more popular and widely used in the market, so it’s easier to get them.

Cost-effective: As many devices need constant voltage power adapters, there’re many manufacturers for them. Compared to other power supplies, a constant voltage power supply costs less.

Constant Current Power Supply

Provide a stable power source: The constant current power supply keeps the current stable, which could avoid burnout/thermal runaway from the significant current. Steady current is vital for precision instruments because they are susceptible to changes in electricity wind.

Control applications easily: The constant current power supply makes it easier for designers to control applications. Such as keeping a light in stable brightness.

Application of the two kinds of Power Supply

Different power supplies are applied for different devices. What are they applying for? Let’s figure out this.

Constant Voltage Power Adapter Application

A constant power supply gets the power voltage (120-277VAC) from a wall outlet at home. It can convert the AC(Alternative Current) power to the lower DC(Direct Current) power, which keeps the devices working well. The constant voltage is helpful for many applications, like LED strip lights, home and office appliances, industrial equipment, etc.

If the LED strip requires 12VDC, there is no need to question whether you want a constant current driver. This source has an onboard circuit that controls the current to be steady. So, all your need is a 12VDC constant voltage source.

Constant Current Power Supply Application

The constant current power supply operates in a variety of applications.
If the current fluctuates, the LED lighting brightness will also change.
This isn’t a big deal for small screens, but if you have many lights, the brightness shift is noticeable, so you need a steady current. Thus the constant current LED driver will be helpful for the LED lights which need stable brightness.

Moreover, the voltage and current at charge are not proportional. This is due to the nature of rechargeable batteries. As a result, a constant current power supply is valuable. It ensures the battery gets the same present amount, regardless of the voltage.

How to Clarify if we need a Constant Voltage Power Adapter or a Constant Current Power Supply?

A constant voltage adapter can be less expensive and simpler to build for applications that use bright or contrasting colors, such as signs, LED tapes/LED strip lights, and other similar uses. However, a constant current power supply might be preferable when the final application is lighting. More precise regulation of light quality and intensity is made possible, and it is possible to fine-tune LED systems to keep them running as efficiently as possible.

The application of a constant voltage adapter is wider than the constant current power supply, such as LED strip lights, LED screens, LED signs, home and office appliances, business equipment, industrial devices, telecommunication equipment, etc. While the constant current power supply is applied for LED lights for brightness use, rechargeable batteries charging, and precision instruments.


The Constant Voltage Power Adapter and Constant Current Power Supply are available in the market. They are both available for LED products. To figure out if we need a constant voltage power adapter or constant current power supply, it depends on what usage we need the LED products for. If for brightness or color-changing, the constant voltage power adapter is better; if for lighting, the constant current power supply is preferable. If there are any questions, we’re here to help.

Are you trying to get the right power supply vendor? Let a reliable supplier provide you with high quality power supply solutions.

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