电流电流能力和电流传感器IC的熔丝特性，具有50至200个测量功能
电流电流能力和电流传感器IC的熔丝特性，具有50至200个测量功能
由Evan Shorman，Caleb Mattson和Shaun Milano，Allegro M亚博棋牌游戏icrosystems
Introduction
亚博棋牌游戏Allegro Microsystems提供广泛的电流传感器IC解决方案，该解决方案分为两个主要类别：IC，具有集成的电流承载导体和设计用于外部磁芯的IC。在具有集成电流承载导体的电流传感器IC中，有两个包可用于测量50到200 A的电流[1]: the LR and the CB. Because of the integrated current-carrying conductor, these ICs are placed in series with the current to be measured. To reduce power dissipation on the integrated conductors, the resistance is very low (200 μΩ for the LR package and 100 μΩ for the CB package). It is still important to know the thermal performance of these ICs when they are subjected to DC currents, short circuits, inrush currents, or any other fault condition. In this way, designers can design PCB layouts and protection features to optimize current sensor performance and to understand the boundary conditions in the application.
背景
Both the CB (Figure 1) and LR (Figure 2) packages are evaluated in this application note. Several devices are offered in these packages, as shown in Table 1 and found on the Allegro website (click device numbers below for more information).
表1：设备和包装产品
测试执行
Thermal performance of Allegro current sensor ICs is subjected to two types of tests: high-current transient pulse tests and DC constant-current tests. In the first tests, the package is subjected to a current pulse of a set magnitude and the time is measured for two boundary conditions: the time for the die temperature to go above the maximum junction temperature (165°C), and the time to fuse the current conductor open. In the second tests, the package is subjected to a constant DC current and the steady-state die temperature increase is recorded.
注意这些测试取决于印刷电路板设计。对于在本应用笔记中执行的所有测试，将设备焊接到标准Allegro评估板[2]（图3和图4）。电路板的散热特性将根据PCB布局以及其他附近设备的影响而变化。对于小于150 A的电流尤其如此。这些测试的目的是提供测试的散热性能的总指导。每个包装的热性能应在要使用的特定应用中验证。通过以下几个基本布局指南，可以轻松实现Allegro演示板热性能。
热性能布局指南
When laying out a PCB for an Allegro current sensor IC, there are a few key elements that will help with thermal performance. These include: dense thermal vias surrounding the solder pad locations, multiple layers of metal directly under the current path to help spread the heat, and locating any heat sinking elements as
尽可能靠近设备（参见图5）。所用的评估板是典型的2盎司铜的每个8层板。通常，只要PCB的布局进行小心并考虑热性能，就不需要大于2盎司的铜层。
High-Current Pulse Testing
LR和CB封装的高电流脉冲测试在多峰电流水平下进行。所有数据均为25°C环境温度。只有LR封装的结果如图6所示，因为实验室设备的最大电流能力仅为700a，这是不足以导致CB封装的任何熔断器。
参考图6，绿色区域是安全操作区域（这意味着不超过最大结温）。橙色区域表示超过了最大结温的区域，但电流导体尚未融合。LR封装上的高电流脉冲测试的结果显示，在300A时，最大结温需要超过2秒的时间。在675A处，熔丝点和最大结温的点在几乎同时发生在约100ms。
直流电流能力
DC current capability tests were performed on both the LR and the CB package. The results are shown in Figure 7. The results from both packages show an impressive current capacity. The CB package shows more capacity than the LR package; however, the LR package is much smaller and has double the resistance through the current-carrying conductor, so this is to be expected.
对于LR封装，在50 ADC中，仅增加20°C。通过CB封装，在100 ADC，仅增加20°C。该数据在25°C环境温度下拍摄，但可用于在任何工作温度下缩小传感器。
结论
该应用说明的测试结果显示了LR和CB包装的令人印象深刻的热特性。LR封装可以处理大量的电流，特别是考虑其小占地面积仅为6.4 mm×6.4 mm×1.5 mm。CB包装，一个更大的包装，具有令人印象深刻的电流能力 -
able to handle 200 ADC with only ~85°C temperature increase. The data contained within this application note can be used as a guide when designing-in Allegro current sensor ICs and to derate the continuous current for applications over the application operating temperature range. Visit the Allegro电流传感器着陆
页。
1对于需要亚博尊贵会员<50 a的应用程序，请参阅//www.wangzuanquan.com/en/insights-and-innovations/technical-documents/hall-yefcect- sensor-publications/dc-and-transient-current-capability-fuse-characteristics.想要查询更多的信息。