Author:
Ally Winning, European Editor, PSD
Date
02/24/2026
PDF
Frederik Dostal, Subject Matter Expert for Power Management, Analog Devices
Efficiency is perhaps the most important of all metrics in these energy conscious days. That makes measuring efficiency accurately a necessity for all devices, but most importantly for power supplies. Power supplies usually take the mains, or an intermediate voltage and convert it into one that can be used by components in the design. As efficiency is multiplicative, the better the efficiency of the power supply, the better for any overall design.
Calculating a result from the component data sheets that make up the power supply can provide a good estimate of the final efficiency, but the real result can only be found through testing. Measuring efficiency is pretty straightforward, it is just the ratio of output power to input power, and then multiplied by 100 to give the percentage if required. To get those figures, the input current, input voltage, output current and output voltage must be measured. All of those figures are easy to assess in their own right, but the equipment can be quite expensive, space consuming, and require coding to synchronize the equipment and program the tests. In general, two ammeters, two voltmeters, a power supply and a load are required as a minimum. Normally a dynamic load is used to get a more comprehensive overview and simulate real-life conditions.
To simplify the process of efficiency testing, Analog Devices has integrated the voltage and current measurement devices, along with the electronic load, into a single box. The new EVAL-LTPA-RL2000 is an inexpensive solution that includes a 30A current meter, two ±125V voltmeters, and a programmable 10µA to 30A current load. It is part of the LTpowerAnalyzer ecosystem, and can be used with other equipment in the family, or as a stand-alone tool. The device is connected thorough a USB cable to a PC running LTpowerAnalyzer software, which can be programmed to vary the load, log results and output an easily understood graph.
Frederik Dostal, Subject Matter Expert for Power Management at Analog Devices clarifies, “The EVAL-LTPA-RL2000 optimizes efficiency measurement in terms of size, accuracy, speed and cost. It's a portable measurement platform designed for evaluating and characterizing the efficiency of a DC power supply using the LTpowerAnalyzer system. It also has a very accurate dynamic electric load. The volt meters on the input side and on the output side of the power supply can read plus or minus 125V – a very wide range. It is easy to set up, and the free software can easily set all of the parameters, such as output current, and the range of output currents to be measured, before carrying out the test.”
It can also be used to provide additional features, such as the ability to accurately test ultra-low-power devices without highly specialized equipment. Dostal explains, “if the device under test is a nano-power device, for energy harvesting or similar applications, there may only be a very small output current. Efficiency measurements then become tricky. First of all, very high accuracy voltmeters and current meters are required. In addition, there will be some leakage current through the voltage sensing, and that can make up a big proportion of the total power budget. The EVAL-LTPA-RL2000 has the accuracy required to measure those very low levels of power precisely, and the software has the capability to remove the leakage current from the measurement results, giving the true efficiency. The setup is not only good for 30A on the output, it is also optimized for very small scale currents, which is unusual, especially with such an easy set-up.”
Two EVAL-LTPA-RL2000 can be used together, using the same control software, to provide measurements of up to 60A. There is also another scenario where that ability to link systems may come in useful. Dostal expands, “If we have a power supply, with external MOSFETs and external drivers. That often needs two input voltages. Or, there may be a second voltage required for biasing. Whatever the reason, two EVAL-LTPA-RL2000s can be attached to a PC, and then share data, so that a complete efficiency plot is generated that takes both input voltages into account.”
Finally, the device is capable of compensating for voltage drop as loads are switched to give a true representation of the efficiency at a constant voltage. The feature can easily be enabled or disabled.
