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Bench Power Supply Basics

What is a Bench Power Supply?

DC power supplies are standard pieces of test and measurement equipment on every electrical engineer and circuit designer’s bench. They provide DC (direct current) voltage to a device under test such as a circuit board or other product being validated.

The equipment is typically set up on the engineer’s work area or bench (hence the term “bench power supply”).

A variety of types are available all with different features and functions to suit design and debug applications. This blog provides an overview of the bench power supplies available as well as some common functions and features to consider based on your needs.

Watch video to learn more about bench power supplies

Types of bench power supplies

Single vs. multi-channel power supplies

Single channel power supplies have one output that can be controlled whereas multiple channel power supplies have two or more outputs. Multi-channel power supplies are best for developing devices with both digital and analog circuitry or bipolar circuitry.

Keithley 2230G mulit-channel bench power supply

Bipolar vs. Unipolar power supplies

Unipolar power supplies are only able to source a positive voltage though you can switch the leads to source a negative voltage. Bipolar power supplies function in both the positive and negative voltage realms. Bipolar supplies, while able to handle a wider variety of power applications, are more expensive and complex to use so many engineers choose a unipolar supply for most DC power applications.

Linear vs. switching power supplies

A linear power supply has the advantage of outputting very high accuracy measurements with very little noise or signal interference. However, they are typically larger in size and deliver less power with less efficiency. Switching power supplies on the other hand, deliver lots of power in a more compact form factor, but along with that comes high frequency noise and less accurate measurements.

In general, a switch mode power supply is used to test portable equipment because of its compact form factor. A linear power supply is typically used when your application requires powering delicate analog circuitry.

Linear power supply (2200-20-5)
Switching power supply (2260B series)

Bench power supply functions and features

More advanced bench power supplies can operate as a battery simulator. These power supplies will have an option to add an internal resistance to the power supply that simulates the operation of a battery.

An important function a power supply provides is the ability to operate in constant current and constant voltage modes. In constant voltage mode, the power supply will source a constant voltage and the current will vary as the load varies. Similarly, in constant current mode, you can set a voltage high enough for your load that it will deliver the current you want while the power supply maintains a steady current at the level you set.

Most power supplies have a remote volt-meter (also known as "remote sense") feature allowing you to get a clean voltage reading at the device under test rather than at its input terminals. This allows the power supply to compensate for voltage drop along the test leads and ensures that the voltage you set is applied properly at the device.

Finally, many bench power supplies come with test sequences that allow a basic level of programmability. One common test sequence lets you to change the output voltage at set times so you can continue with your testing without needing to continually adjust the settings on your power supply.

Bench power supply and battery simulator (Keithley 2281S-20-6)

More information

For more information about bench power supplies or to get help choosing the right one for your application, please contact Tektronix support or visit these resources below.

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Bench power supply selector guide »

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