Choosing a Benchtop or Laboratory Power Supply

Choosing the right DC power supply for the laboratory or your benchtop is not as easy as it seems. Hitting the “purchase now” button before you carefully consider your needs—both now and in the future—could mean that the power supply will sit on the shelf more often than it’s used on your bench.

Before you purchase your next benchtop or laboratory power supply, carefully consider your output requirements, compare performance specifications, think about how much space you have on your bench or in the lab, and look for features that could come in handy. A little forethought now just might help you select the lab power supply that’s right for you and save time and money in the future.

Output Requirements Drive Power Supply Choices

Your output requirements are perhaps the most important consideration. You need to consider not only the maximum voltage, maximum current, but the total output power that you require. All EA Elektro-Automatik DC programmable power supplies feature TRUE auto-ranging, which automatically offers increased current at lower voltages, enabling a single supply to meet wider test requirements.

In addition to the maximum current and voltage, consider the number of outputs that you’ll need and if the outputs are isolated from one another. Many supplies have multiple outputs, but that limits the amount of power available from each output. In laboratory applications, a more flexible solution would be to configure a system of single-output supplies, whose outputs can be connected in series and in parallel to achieve the outputs you need to power the systems you’re developing or testing.

Of course, when considering your output voltage and current requirements, and the number of outputs you need, think about your future needs as well as your current needs.

Key Performance Specifications For DC Power Supplies

There are a number of important performance specification for a lab or benchtop supply, including:

• Load regulation. This is a measure of how much the voltage or current output will change in response to a change in the load.
• Line regulation. This is a measure of how much the voltage or current output will change in response to a change in the input voltage.
• Output noise. This is a measure of how much noise there is on the supply output. Evaluate both the common mode and normal mode noise.
• Transient response. This is the time it takes for the output voltage or current to return to the programmed value after a change in the load.
• Slew rate. This is the rate at which an output changes from the current state to a programmed state. This specification might be important if you’re using the supply to run automatic tests that call for the output voltage or current to change frequently.

For most lab applications, you’ll want to choose a supply with tight regulation and low output noise. The reason for this is that in the lab you want to focus on the circuit or system that you’re designing and testing, and not worry that the power supply could cause the circuit or system to fail a test. Troubleshooting failures or unexpected behavior is hard enough without having to take into account power supply specifications.

Protection Features For Your Critical Devices – And Critical People!

In the lab, safety should come first, both for personnel and expensive prototypes. In addition to over-voltage and over-current limiting, you may want a supply that powers down completely or disconnects the load from the supply when an over-voltage or over-current condition occurs.

Packaging Should Factor Into Your Decision

Compare the footprint, weight, and rack mounting capabilities of the supplies you’re considering. When operated on the bench, a small footprint is important. It may also be important to select a small, lightweight supply if you will need to transport it frequently to where it will be used. On the other hand, if you will need several different power supplies to run your tests then rack-mounting may be a desirable feature.

Other Features

Some other features that you might want to consider include:

• Remote sense. If the supply must be located more than a few meters from a load, the remote sense feature will compensate for the voltage drop across the power supply leads and ensure that the voltage at the UUT is the intended voltage.
• Ease of use. The PS and PSI series feature a 5 -in. TFT touch panel display for intuitive control, setup and programming. The intelligent interface allows you to program and test quickly without having to pore over the manual. This user-friendly touchscreen is a feature not found on many benchtop supplies.
• Computer control (GPIB, USB, RS-232, LAN, etc.). EA offers a wide variety of computer control interfaces, including Ethernet, USB, EtherCAT, ProfiNET, ProfiBUS, CAN, CANOpen, Modbus, Devicenet and RS232 interfaces.
• Built-in function and arbitrary waveform generator. EA’s built-in function generator allows you to output sine, triangle, square, and trapezoidal waveforms, as well as custom arbitrary waveforms. The function generator also allows you to simulate fuel cells and photovoltaics.

Before purchasing an EA benchtop or laboratory power supply, please feel free to contact us for advice. We can help you choose the right model for your application. You can visit the EA website, send an e-mail to sales@elektroautomatik.com, or phone 858-836-1300.