Performing DC-DC Converter Test Using DC Power Analyzers

Modern electronic equipment that uses power system technology faces great difficulties due to the demand for more power efficiency, especially in devices that run on batteries. The main system block that handles power conversion and delivery is the DC-DC converter, which changes DC power from an unregulated to a regulated voltage. Many designers want to perform DC-DC converter tests to evaluate the performance of the DC-DC converter based on efficiency, load and line regulation, power supply rejection ratio (PSRR) analysis, transient response, ripple, and turn-on time. However, DC-DC converter testing on a benchtop environment requires different test instruments such as a DMM, oscilloscope, power supply, and electronics load. The main challenge with a DC-DC converter test is making the instruments work together to do the required measurements properly.

This application note shows how to test a DC-DC converter using Keysight solutions, including a DC power analyzer and an oscilloscope. In addition, Keysight’s automation software offers the framework for creating simple automated tests to fully characterize the DC-DC converter without writing any code, saving much time. Using an example test setup, the application note reviews several key topics:

Efficiency Test

Typically, the most important DC test for the DC-DC converter is efficiency. This is especially true for battery-powered devices, because efficiency has a direct impact on the life of a device. The efficiency of the converter is the ratio between the output power and the input power.

Load Regulation Test

The load regulation test measures the ability of the DC-DC converter to sustain the specified voltage output when the load current (Iload) varies at constant input voltage. To execute this test, after powering up the product, slowly vary the output load between the specified minimum and maximum current values. The measured output voltage changes should be within the range specified in the product’s technical specification. For the test setup, use the same connection employed for the efficiency test.

Line Regulation Test

The line regulation test represents the ability of the DC-DC converter to sustain the specified output voltage while the input voltage is varied between a specified range of voltages. To carry out this test, set the input power source to a value within the input range of the product and power up the product. While monitoring the product output voltage, slowly vary the input voltage between the specified minimum and maximum values. The measured output voltage changes should be within the range specified in the product’s technical specification.

Ripple Test

The DC-DC converter has different internal topologies used at different internal switching frequencies that are reflected in the output ripple frequency. The ripple on the output voltage is measured as rejected input noise on the output voltage using an oscilloscope, with one channel on the input and one channel on the output of the converter.