Agilent HP AN 372-1 Application Note free download

File name HP AN 372-1 Application Note.pdf

Agilent AN 372-1 Power Supply Testing Application Note An electronic load offers a broad range of operating modes, providing versatile loading configurations needed for characterizing and verifying DC power supply design specifications. Introduction As regulated-power supply technology evolves, they are relatively inefficient when compared to testing methods for design verification and product switching power supplies, and tend to be large function require more sophisticated electronic equip- and heavy due to the heat sinks required to contin- ment. The different power supply architectures uously dissipate power from the series transistors and output combinations also dictate the need for and due to the magnetics used in this design. Typi- versatile test instruments that can accommodate a cally, linear power supplies provide a most effec- broad range of specifications. As a result, one test- tive solution in lower power applications, and are ing requirement that has been growing in impor- often used as subassemblies in various products. tance is the method of loading the power supply under test. The need for a higher degree of load Switching power supplies address the disadvan- control due to test sophistication, such as the need tages of linear power supplies (namely the low effi- for computer programmability, has increased the ciency and relatively large size and weight), and demand for electronic load instruments. The follow- are therefore a more effective and less costly solu- ing examination of the most common power supply tion for high power applications. The relative dis- architectures or topologies clearly illustrates the advantages occur in three areas when compared to growing need for higher performance and versatility linear power supplies: slower transient recovery in electronic loads and power supply test equipment. time, higher PARD, and lower reliability. Switching power supplies are used in a wide variety of indus- An Overview of Power Supply Topologies tries and environments, and are commonly found Of all the possible power supply topologies, linear as subassemblies in products such as computers, and switching regulation techniques are the most computer peripherals, and copiers. Recent power common design implementations. Linear power supply designs combine the best features of switch- supplies are typically used in R&D environments ing and linear topologies. Below, Table 1 compares and in production test systems because they pro- the typical specifications for linear and switching vide high performance, low PARD (ripple and noise), topologies. excellent line a