Butnicu Dan
Basics of Electronics, Telecommunications and Information Technology Faculty, Technical University "Ghe.Asachi" of Iasi, 700050 Iasi, Romania.
Micromachines (Basel). 2023 Jan 15;14(1):221. doi: 10.3390/mi14010221.
Many recent studies have revealed that PoL (Point of Load) converters' output capacitors are a paramount component from a reliability point of view. To receive the maximum degree of reliability in many applications, designers are often advised to derate this capacitor-as such, a careful comprehending of it is required to determine the converter's overall parameters. PoL converters are commonly found in many electronic systems. Their most important requirements are a stable output voltage with load current variation, good temperature stability, low output ripple voltage, and high efficiency and reliability. If the electronic system in question must be portable, a small footprint and volume are also important considerations-both of which have recently been well accomplished in eGaN transistor technologies. This paper provides details on how derating an output capacitor-specifically, a conductive tantalum polymer surface-mount chip, as this type of capacitor represented a step forward in miniaturization and reliability over previously existing wet electrolytic capacitors-used within a discrete eGaN-FET-based PoL buck converter determines the best performance and the highest MTBF. A setup based on an EPC eGaN FET transistor enclosed in a 9059/30 V evaluation board with a 12 V input voltage/1.2 V output voltage was tested in order to achieve the study's main scope. Typical electrical performance and reliability data are often provided for customers by manufacturers through technical papers; this kind of public data is often selected to show the capacitors in a favorable light-still, they provide much useful information. In this paper, the capacitor derating process was presented to give a basic overview of the reliability performance characteristics of tantalum polymer capacitor when used within a DC-DC buck converter's output filter. Performing calculations of the capacitor's failure rate based on taking a thermal scan of the capacitor's capsule surface temperature, the behavior of the PoL converter was evaluated.
最近的许多研究表明，从可靠性的角度来看，负载点（PoL）转换器的输出电容是一个至关重要的组件。为了在许多应用中获得最高程度的可靠性，通常建议设计人员对该电容进行降额使用——因此，需要仔细了解它，以确定转换器的整体参数。PoL转换器在许多电子系统中都很常见。它们最重要的要求是在负载电流变化时输出电压稳定、良好的温度稳定性、低输出纹波电压以及高效率和可靠性。如果所讨论的电子系统必须是便携式的，那么小尺寸和小体积也是重要的考虑因素——最近在氮化镓（eGaN）晶体管技术中，这两个方面都得到了很好的实现。本文详细介绍了如何对输出电容进行降额，具体来说，是对一种导电钽聚合物表面贴装芯片电容进行降额，因为这种类型的电容在小型化和可靠性方面比以前的湿式电解电容有了进步，它被用于基于分立eGaN场效应晶体管（FET）的PoL降压转换器中，以确定最佳性能和最高平均无故障时间（MTBF）。为了实现该研究的主要目标，对一个基于EPC eGaN FET晶体管的装置进行了测试，该晶体管封装在一个9059/30 V评估板中，输入电压为12 V，输出电压为1.2 V。制造商通常会通过技术论文向客户提供典型的电气性能和可靠性数据；这类公开数据往往是经过挑选的，以便以有利的方式展示这些电容——不过，它们仍然提供了许多有用的信息。在本文中，介绍了电容降额过程，以对钽聚合物电容在DC-DC降压转换器输出滤波器中使用时的可靠性性能特征进行基本概述。通过对电容外壳表面温度进行热扫描来计算电容的失效率，从而评估PoL转换器的性能。
