Power Supplies / Sources

Facts and Frequently Asked Questions (FAQs) about Power Sources, Laboratory Power Supplies, Power Supplies and Programmable Lab Power Supplies

DC Power Supplies: Core Functions and Application Areas

DC power supplies are precise direct current sources used in electronics development, validation, and ATE test systems. They provide stable DC voltage and current in CV/CC operation (Constant Voltage / Constant Current) and support remote sensing to compensate for line losses. In both laboratory and production environments, they enable reproducible test profiles, high resolution and accuracy, as well as integrated protection functions (e.g. OVP, OCP, OPP). This makes them a reliable foundation for testing electronic assemblies, sensors, actuators, power modules, and battery or accumulator applications.

AC Power Supplies: Versatile Power Sources for Professional Applications

AC power supplies generate alternating voltages with variable amplitude, frequency, and waveform (sine, square, or distorted forms). The resulting alternating current is ideal for mains simulation, dips/interrupts, flicker, and harmonics/THD tests in compliance environments.

As standalone AC power sources, laboratory power supplies are used in medical technology, telecommunications/IT, household and industrial equipment, as well as in inverter and drive pre-compliance testing. They offer a flexible, traceable source with remote control (LAN/USB/GPIB) and integrated logging functions.

Why Adjustable Power Sources Are Essential

Adjustable, programmable power supplies (including laboratory power supplies) are essential wherever precise voltage and current levels or reproducible sequences are required. They enable ramps, pulse and step profiles, limit values, and automated test sequences via SCPI or API – indispensable in research labs, end-of-line testing, and technical service. The result: higher process reliability, faster test execution, and auditable documentation with clear data for every unit under test.

Technical Details of Programmable Power Supplies

Programmable laboratory power supplies (DC) and AC power sources offer advanced features such as list mode, sequence editor, and trigger I/O for automated and reproducible tests. Depending on the model, they support multi-channel operation – for DC via master/slave configuration (serial or parallel) and for AC via power or phase synchronization (1/2/3-phase).

Profiles control voltage and current behavior in DC operation, and amplitude, frequency, waveform, and phase in AC operation. Thanks to these different types of power supply, component and semiconductor characterization, power integrity analysis, mains simulation, and inverter testing can be performed with high precision. Remote sensing, high resolution, and low noise – for AC additionally low THD – ensure reliable measurement and repeatability in demanding test environments.

Advantages of Programmable Power Supplies at a Glance

• Higher accuracy in display and regulation compared to standard power supplies
• Protection against overload and short circuit (OVP, OCP, OPP) at the outputs
• The output can be electrically disconnected to ensure safe voltage and current isolation from the load during switching and setup operations.
  
• Adjustable limits for current, power, and voltage
• Interfaces (LAN, USB, GPIB) for PC/ATE control including SCPI and data export
• Master/slave function for power scaling via serial or parallel connection of multiple devices

FAQs

What is the difference between a DC and an AC power supply?

DC power supplies deliver direct voltage and current – ideal for module and battery testing with constant voltage. AC power supplies generate alternating voltage with adjustable frequency, amplitude, and waveform. These power sources are therefore ideal for mains simulation and compliance testing.

Where are laboratory power supplies used?

Laboratory power supplies are indispensable in electrical engineering – for example in electronics development, testing and service departments, and ATE systems. They are increasingly used in advanced DIY and hobby projects that require programmable profiles and logging functions. Voltage ranges extend from 0–100 V in the lab up to several kilovolts in high-power development environments.

What is a variable or adjustable power supply?

A variable and programmable power supply allows the user to set the output voltage and current individually. The range of adjustment depends on the model. Key factors are fine resolution, high stability, and precise limit control for research and testing purposes.

Are laboratory power supplies adjustable power supplies?

Yes. Laboratory power supplies by definition allow regulation of voltage and often also current. They feature protection and limit functions, remote-sense connections, and common interfaces for automation.

What is the difference between switching and linear power supplies (transformer-based)?

Switching Power Supply – Operating Principle

The mains voltage is first rectified. A high-frequency switching regulator generates a signal that is processed via an HF transformer. On the secondary side, rectification and regulation ensure a stable DC supply – compact and efficient.

Switching Power Supply – Advantages

• High efficiency and low energy consumption
• Compact design thanks to high-frequency transformer (e.g. 1U designs)
• Wide input range and high power density

Switching Power Supply – Limitations

• Higher circuit complexity (control loop, layout, drivers)
• Potential ripple and switching noise – requires EMC compliance
• Sensitivity to mains transients, voltage spikes, and burst events

Typical applications: High-performance test systems, industrial power supplies, and wide-range configurable power systems with specific efficiency requirements, as well as diverse use cases in electrical engineering.

Linear Power Supply – Operating Principle

A transformer steps down the mains voltage to the desired level. The signal is then rectified and smoothed using capacitors. A regulator continuously adjusts the output voltage. The result is a highly stable and exceptionally low-noise DC supply.

Linear Power Supply – Advantages

• Low noise and excellent ripple suppression
• Fast and continuous regulation behavior
• Robust design – ideal for sensitive analog applications

Linear Power Supply – Limitations

• Bulky and heavy due to the mains transformer
• Lower efficiency under load – heat generation
• Limited dropout and adjustment range at high currents

Standard applications: Precision analog environments, audio measurement technology, reference and sensor supplies – wherever low noise is essential.

Practical Notes

• For maximum signal fidelity (μV/nV range, low-noise analog technology), a linear power supply is usually the first choice.
• Where power density, efficiency, and wide input range are critical, a switching power supply is ideal.
• In many labs, hybrid power systems are used: the switching supply provides the main voltage, while downstream linear regulators ensure ultra-low-noise operation.

Conclusion

Programmable laboratory power supplies combine precise control, protective mechanisms, and automation. They accelerate testing processes, increase repeatability, and reduce overall costs (Total Cost of Test) – from research through to serial production.

About LXinstruments

LXinstruments develops and delivers test and measurement technology for functional testing, power systems, and electrical safety – with a focus on the LXI standard. Naturally, we also provide tailored solutions for individual testing applications. Our portfolio covers everything from classic functional tests to customized setups for renewable energy applications.

Visit our shop! Discover a wide range of measuring instruments and accessories – from electronic test equipment to devices for electrochemical measurements. Benefit from our expertise – we support you in device selection, ATE integration, and interface configuration.
If you have any questions, we offer free consultation and detailed information on any type of power supply or source.

Contact:
+49 (0)7032 89592-3
sales@lxinstruments.com
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