Column Control DTX

10 Practical Tips to Help Your Power Testing and Analysis

Application Notes


Want to learn how to reduce noise from your power supply? How about simplifying your test setup? Read on!

A power supply is an integral part of any good test system. The capability to deliver clean and accurate power to your Device Under Test (DUT) removes doubts and gives you the right results every time. Our practical tips will let you get more out of your power supply. If you ever need to get a new power supply, you can count on these tips to help you choose the right one. Remember, more power and features do not mean better a better power supply. It’s about how you use your power supply.

Don’t worry about your power supply. Let us do that for you. We want you to focus on what’s important to you. We hope you enjoy our tips.

Table of Contents:

  • Tip 1: Use Remote Sensing to Compensate for Load-Lead Effects
  • Tip 2: Increase Safety With Remote Disable Feature 
  • Tip 3: Eliminate Noise From Low-Level Measurements
  • Tip 4: Use Down Programming to Increase Test Speed
  • Tip 5: Simplify Setup With Autoranging Power Supplies
  • Tip 6: Connect Power Supplies in Series or Parallel For Higher Output
  • Tip 7: Simplify Battery Drain Analysis With Analysis Tools
  • Tip 8: Characterize Inrush Current With an AC Power Source/Analyzer
  • Tip 9: Use a Power Supply to Measure DUT Supply Current 
  • Tip 10: Create DC Power Waveforms With List Mode 

Tip 1: Use Remote Sensing to Compensate for Load-Lead Effects

When your power supply leaves the factory, its regulation sense terminals are usually connected to the output terminals. This limits the supply’s voltage regulation abilities, even with very short leads. The longer the leads and the higher the wire gauge, the worse the regulation gets (Figure 1). Compare the output impedance of a well-regulated 10 A supply, which might have an output impedance of 0.2 mΩ, with the resistance of copper wire.

And regulation gets even worse if you use a relay to connect power to the load.

Remote sensing, in which you connect the sense terminals of the power supply’s internal feedback amplifier directly to the load, lets the power supply regulate its output at the load terminals, rather than at its own output terminals (Figure 2). The supply voltage shifts as necessary to compensate for the resistance of the load leads, relays, or connectors, thereby keeping the voltage at the load constant.

To implement remote sensing, disconnect the local sense leads from the output terminals. Use a twisted two-wire shielded cable to connect the power supply sensing terminals to the sensitive points on the load. (Don’t use the shield as one of the sensing conductors.) Connect one end of the shield to the ground and leave the other end unconnected.

Sensing currents are typically less than 10 mA, and as a general rule, you should keep the voltage drop in the sense that leads to less than 20 times the power supply temperature coefficient (usually stated in mV/°C). This is easy to achieve with readily available shielded two-wire cable.


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Column Control DTX