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White PaperTest & Measurement

Ensure Protected, Reliable Operation for a DC Power Supply in Any Load Circuit


Connecting a DC power supply to a load appears to be a simple, straightforward task. In many situations, this is true; however, other situations can prove challenging. While manufacturers of DC power supplies design their supplies to be stable when powering any type of load, that does not mean the power supply is impervious to certain load characteristics that can cause problems. An inductive or a capacitive load can apply energy to the power supply, which can damage the power supply’s output stage. The output stage is designed to deliver power, not absorb it. Similarly, active loads, such as batteries, can deliver damaging power to a supply.

As well as delivering energy to the power supply, some capacitive loads, inductive loads and loads that generate substantial rapid changes in load current, can create conditions that lead to oscillation. Both the power supply and the load are susceptible to damage. Furthermore, testing is interrupted since the load is not getting a stable DC voltage for proper operation. Another factor that can cause conditions for oscillation is the wiring between the power supply and the load. Noise can couple into sensitive remote sense lines and interfere with the voltage control circuit.

This white paper will describe various types of loads that can be potentially hazardous to DC power supplies. Also, the following paragraphs will describe the types of loads in a power supply-load circuit as well as wiring conditions that can result in oscillation. For each type of load and circuit condition, we will offer solutions to these challenges. Our recommendations will ensure reliable power supply operation and load protection.

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