Get More Usable Power with Autoranging Power Supply

An autoranging power supply is a good option if your devices need more power, less space and cost, and more safety. This guide will tell you what an auto-ranging power supply is, how it operates, and why it is useful. You will discover how to apply an auto-ranging power supply for devices and applications requiring different power levels. You will also get some advice and suggestions for selecting and using an auto-ranging power supply.

Introduction

Most power supplies provide a single range because it is the most straightforward, cost-effective design. A single-range power supply can deliver its maximum output power using one voltage and current value. However, a single-range solution may not provide a high enough current or voltage for your designs even if the power specification is sufficient. Traditional high-power supplies are not suitable for research and development (R&D) because they are bulky and loud. A power supply’s internal components include voltage tolerances, the maximum output power, and fans that dissipate heat coming from the components. Conventional power supplies can also cause problems for the device under test (DUT) because they generate more output noise. Programmable DC power sources are an essential tool in product development and production testing of a wide range of electronic devices and systems. In many instances, functional test requires submitting the device-under-test (DUT) to a wide range of operating conditions. In some cases, the DUT draws constant power under variable input conditions. Common examples are DC motor drives and regulated DC/DC supplies. In such circumstances, the ability of the programmable DC source to provide more current at reduced output voltage is valuable. We refer to this ability as “autoranging.” DC supplies without autoranging often require users to use multiple supplies to test the DUT under varying input voltage conditions.

What is an Autoranging Power Supply?

“Autoranging” describes the ability of a programmable DC source to maintain full power output across a wider range of output voltages and currents than traditional DC power supplies. In most applications, a DUT will not require a power supply’s full-scale voltage, meaning that the power supply is not fully used. As a result, in many cases, an engineer will have to specify a more expensive power supply that can supply the necessary output power at the required voltage.

Autoranging power supplies, on the other hand, are not as constrained; they automatically supply higher output current at lower voltages. When current outputs are modest, autoranging supplies can provide a higher output voltage than traditional supplies.

This feature gives autoranging power supplies extra range and more flexible performance than conventional supplies. When it appears on a voltage-current graph, an autoranging output characteristic looks like an infinite number of overlapping rectangular output characteristics capable of maximum power (Pmax). An autoranging power supply cannot output Vmax and Imax at the same time, but it can provide more voltage-current combinations than a dual-range power supply.

In the past, the solution for higher current was to use a more powerful single-range power supply. A larger power supply typically means higher output noise and more difficulty controlling smaller currents. But autoranging provides more current at higher voltages, resulting in more usable power.