# What is CC and CV in Power Supplies?

You’ve probably heard the terms CC and CV thrown around when talking about power supplies, but what do they actually mean? In this comprehensive guide, we will answer all of your questions about CC and CV in power supplies. We’ll discuss what each term means, how they differ, and provide tips on how to choose the right one for your needs. So whether you’re a beginner just starting out in the world of electronics or a seasoned pro looking to learn more, read on for all the info you need!

## DC Power Supply in General

A DC power supply is a device where current flows only in one direction. This makes it different from the AC power supply, which changes directions periodically. The voltage and current can be controlled independently by the user, making it very versatile. It is used to power electronic devices that require a stable DC voltage, such as computers and radios.

There are two types of DC supply, linear and switching. A linear power supply is the most common type of DC power supply. It uses a transformer to convert the varying DC voltage into a different, lower DC voltage. On other hand, switching power supplies use transistors to switch the DC voltage on and off at high frequencies, which is then converted to AC.

The output of a DC power supply can be either constant voltage (CV) or constant current (CC). CV mode means that the output voltage will be constant, regardless of the load. CC mode means that the output current will be constant, regardless of the load.

Electron Bot Quote

In my view, the world of DC power supplies presents two main players: the reliable linear type and the dynamic switching variant. Linear supplies, with their trusty transformers, step down DC voltage. On the flip side, switching supplies tap into transistors, toggling DC at high frequencies. Whether it’s constant voltage (CV) or constant current (CC), these modes define stability in the face of varying loads, making DC power supplies versatile for different applications.

David Wilson, Systems Architect, Seattle

You can control only one parameter at a time, while the other parameter is determined by the load and Ohm’s law.

Most power supplies have both CV and CC modes, which can be selected using a switch on the front panel. In some cases, the two modes may be combined into a single mode, known as constant voltage/current (CV/CC) mode. In these models, each mode will have a light assigned to it, so you can see which mode is active. [1], [2], [3]

## Role of DC Power Supply

Power supplies are available in a variety of shapes, sizes, and capabilities.

Depending on their intended use, some have features that make them more suitable for certain applications than others. For example, regulated power supplies are designed to maintain a constant output voltage regardless of changes in input voltage or load resistance. This makes them ideal for powering devices that require stable voltages, such as computers and other electronic equipment. Unregulated power supplies do not have this feature, but they are typically smaller and less expensive than regulated ones.

One of the most important things to consider when choosing a power supply is its parameter regulation. This determines how well the power supply can maintain a constant output voltage or current. The two most common types of voltage regulation are constant current (CC) and constant voltage (CV). We will explain each of these in detail. [2]

### Definition of CC

Constant current power supplies are designed to deliver a constant amount of current to the load, regardless of changes in input voltage or load resistance.

CC mode operation is relatively simple. The controller constantly measures the output current and compares it to the setpoint. When the output current exceeds the setpoint, the controller reduces the duty cycle to lower the current. Conversely, when the output current is below the setpoint, the controller increases the duty cycle to raise the current.

This process continues until the output current reaches the desired level and remains constant. The power supply will continue to make small adjustments to maintain a constant current, even as load conditions change.

The advantage of CC mode is that it can help to prolong the life of your device by preventing it from being overloaded. The downside is that it may not be suitable for all applications.

If you are using a power supply in CC mode, it is important to set the maximum voltage value of your supply to a value greater than the value of voltage calculated by Ohm’s Law and the resistance value of the load.

### Role of CC mode

Monitors output current

As we mentioned, the CC monitors the output current and keeps it at a constant level. When the load current changes, the CC adjusts the duty cycle to maintain a constant current. It also regulates the current needed to maintain the voltage at a certain level. If the voltage exceeds the set value, CC will turn off the power supply to prevent damage.

This is useful for loads that have a variable or unknown resistance, such as LEDs and laser diodes. By keeping the current constant, you can be sure that the LEDs are always operating at their rated forward voltage and will not be damaged by excessive currents, which increases their lifespan.

Electron Bot Quote

In my perspective, Constant Current (CC) mode is the unsung hero for sensitive loads like LEDs and laser diodes. Its vigilant monitoring and adjustment of output current ensure these components operate within safe limits, enhancing their lifespan. This mode’s role in preventing excessive power dissipation makes it a crucial ally in applications where efficiency and longevity are paramount.

Robert Miller, Network Engineer, Austin

CC mode is also useful for applications where power dissipation must be kept low. By monitoring and regulating the load current, CC mode prevents excessive power dissipation in both the load and power supply. [4], [5], [6]

### Definition of CV

The CV in a power supply stands for constant voltage. This means that the power supply will maintain a steady voltage output regardless of changes in load. The main advantage of this type of power supply is that it is very simple to use and provides very stable performance.

CV mode is usually used for semi-automatic or automatic assembly processes that require a consistent voltage. For example, the CV power supplies are usually employed in city lights.

### Role of CV mode

Monitors the output voltage

One of the key features of a CV power supply is that it monitors the output voltage and automatically adjusts itself to maintain a constant voltage. This means that if the load on the power supply increases, the power supply will increase its output voltage to compensate, unless the maximum power limit is reached. This makes CV power supplies very easy to use and helps to ensure that they provide stable performance. [5], [7], [8]

### Differences Between CC and CV

Now it’s time to sum this all up. The basic difference between CC and CV is that in CC mode, the power supply regulates the current flowing through the load, while in CV mode it regulates the voltage across the load. In addition, while in CC mode, the output current is kept constant, while the voltage varies. In CV mode, the opposite is true – the voltage is kept constant, while the current varies.

In practice, this means that when you set a CC power supply to deliver a certain current (say 20mA), it will maintain that current even if the voltage across the load changes (within limits). Similarly, if you set a CV power supply to deliver a certain voltage (say 12V), it will maintain that voltage even if the current flowing through the load fluctuates. So which one should you use?

It depends on your application. If you need to deliver a very precise amount of current to your load (for example, if you are powering an LED), then CC is the way to go. On the other hand, if you need to maintain a very precise voltage across your load (for example, if you are powering a microcontroller), CV is the better choice. [4], [5], [7]

## What is a CP Mode?

Besides CC and CV, there is a third mode of operation for power supplies called CP or constant power. In this mode, the maximum output power is limited at the set value. The voltage and current will be automatically adjusted to maintain a constant output power as the load changes. [5]

## FAQ

### How to switch between CV to CC?

To switch between CV to CC, first make sure that your power supply is turned off. After that, locate the mode switch on your power supply. Once you have found the mode switch, simply toggle it to the desired setting.

It’s really that easy! Now you know how to switch between CV and CC on your power supply. Just remember to always turn off your power supply before making any changes.

### Are LED drivers constant current?

LED drivers can be constant current (CC) or constant voltage (CV). A CC LED driver will maintain a constant current flowing through the LED no matter what the voltage is, while a CV LED driver will attempt to provide a constant voltage.

Most LEDs have a fairly linear relationship between forward current and forward voltage. This means that, for a given LED, increasing the forward current will cause the forward voltage to increase at approximately the same rate.

### How does CC work?

CC, or constant current, mode on a power supply regulates the amount of current flowing from the power supply to the load. CV, or constant voltage, mode on a power supply regulates the amount of voltage present at the load terminals.

In CC mode, the voltage will vary as required in order to keep the current constant. The advantage of this is that it is easy to control how much current is flowing into your circuit and you don’t have to worry about damaging your components with too much current.

The downside of CC mode is that it can be difficult to get a precise voltage reading at the load because the voltage will be constantly changing.

## Conclusion

In this article, we’ve looked at the two modes that a DC power supply can operate in – CC and CV. We’ve seen how CC mode adjusts the current to maintain the set voltage, while CV mode adjusts the voltage to maintain the set current. Both of these modes are important for ensuring stable power supplies, and it’s important to be aware of which mode your power supply is operating in so you can use it correctly. Thanks for reading!

References:

1. https://compocket.com/blogs/news/what-is-dc-power-supply
2. https://www.monolithicpower.com/en/ac-dc-power-supply-basics
3. https://mastechpowersupply.com/what-is-a-cc-cv-power-supply.html