DC和瞬态电流能力/表面安装电流传感器IC的熔丝特性
DC和瞬态电流能力/表面安装电流传感器IC的熔丝特性
By Alex Latham and Scott Milne,
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Introduction
雷竞技竞猜下载Allegro MicroSystems提供具有集成导线的广泛产品系列电流传感器IC解决方案。这些产品可用于测量各种应用中的电流，包括电机控制，逆变器，负载检测和管理以及过流故障检测。雷竞技最新网址对于高达雷竞技最新网址80a的正常操作电流的应用，Allegro在许多标准表面安装封装中提供电流传感器IC，例如SOIC-8，SOICW-16，QSOP-24和QFN [1]。由于其集成导体，这些传感器IC与它们测量的电流串联放置。根据包装，集成导体尤其是低电阻（1.2MΩ至低于0.3mΩ），因此它们在正常操作条件下产生很小的热量。然而，与当前路径中的所有组件一样，重要的是要了解由于短路，浪涌电流或其他瞬态条件的额定标称能力高于其额定标称能力的电流。
图1: Sensor IC Comparison
测试执行和结果的限制
本研究的重点是SOIC-8，SOICW-16和基于QFN的电流传感器ICSLEXGRO提供。值得注意的是，即使它们使用相同的通用SOIC-8或SOICW-16占地面积，这些封装的内部结构也可能因产品而异。具体地，测试的包装和相关产品如表1所示。
| 包 | Conductor | 产品 |
| SOIC-8 | LC1：1.2MΩ | ACS711KLC. |
| ACS712. | ||
| ACS713 | ||
| ACS714 | ||
| ACS715 | ||
| ACS724LLC | ||
| ACS725LLC | ||
| ACS730KLC | ||
| ACS71240 | ||
| LC2：0.65mΩ | ACS722LLC | |
| ACS723LLC. | ||
| SOICW-16 | 洛杉矶：1MΩ | ACS710 |
| ACS716. | ||
| ACS720 | ||
| ACS732KLA | ||
| ACS733KLA | ||
| 马：0.85mΩ | ACS717. | |
| ACS718 | ||
| ACS722KMA | ||
| ACS723KMA | ||
| ACS724KMA | ||
| ACS725KMA | ||
| ACS732KMA |
||
| ACS733KMA |
||
| ACS71020 | ||
| MC: 0.265 mΩ | ACS724 |
每包都经过以下测试：
| High Current Pulse Behavior （保险丝特性） |
Time to reach 165°C die temperature vs. current |
| 是熔化当前导体的时间打开电流 | |
| 直流电流能力 | Die temperature vs. DC current and ambient temperature |
除非另有说明，否则此处提出的所有数据都在室温下收集到焊接到Allegro开发的产品专用示范板的产品2. The heat dissipation characteristics, particularly at moderate currents (<150 A), will vary depending on the PCB layout used for the high current traces near the current sensor IC. Other factors, such as whether or not the PCBA is encapsulated with a conformal coating (i.e., if it is “potted”) and the enclosure that the PCBA is placed into can impact the thermal characteristics of the system. The purpose of this study is to compare and contrast the relative performance of the various product families listed above and give a general idea of what levels and durations of current each package is capable of withstanding. The high current carrying capability of these parts should be verified in the specific application conditions they will be used in.
试验结果
High Current Pulse Behavior (Fuse Characteristics)
当Allegro的集成导体电流传感器IC暴露于高电流时，存在两种不同的故障模式。根据流过导体的电流的幅度和持续时间，可能发生以下任一或两种故障模式：
- 由于热曝光，模具可能被损坏，如果模具经受上述温度，则可能发生这种情况165°C.
- 主要导体将作为保险丝和开放。
图2shows the time vs. current curves of these failure modes for the LC1 package (ACS712/3/4/5 and ACS724/5 devices). The blue curve represents the time until the conductor fuses open, and the black curve represents the time until the die reaches 165°C. At moderate currents (<150 A), these sensor ICs tend to overheat before fusing, which means that the PCB layout and application assembly can have a significant impact on the time to failure at these current levels, as they can help or hinder the flow of heat away from the sensor IC. For higher current transients (>150 A), the sensor ICs tend to fuse open before overheating the die. The time to fuse for these events is mainly dependent on the size and shape of the integrated conductor and will vary less from application to application. Ultimately, one should stay within the Safe Operating Area, below both the fusing and overheating curves, and Figure 3 shows the safe operating region for each of the packages tested.
图2: Fuse and Over-temperature Time vs. Current for the LC1 (SOIC-8) Package Type
wh除了失败的时候,失败的行为en the sensor IC fuses is also important. In general, when the integrated conductor fuses, the thinnest part of the conductor disintegrates, and the package may crack. In all of the testing performed, when the device fused before overheating, the failure did not result in any shorting between the primary and secondary of the device. However, the isolation rating of the device will be compromised if the package has been damaged.
图3.: Safe Operating Area - Time for die temperature to reach 165°C or fuse (whichever occurs first) vs. current.
It is also critical to note that if the package is overheated before fusing, the fusing event will be much more energetic. These types of failures occur in the light grey region of Figure 2 (beyond the Safe Operating Area), as that is where one overheats the package before fusing. In those scenarios, significant heat is present, and the response to any overcurrent event in these conditions will be more energetic. Figure 4 shows the time to fuse for each of the packages tested for reference. However, it is important to point out that the part should only be operated in the Safe Operating Region shown in Figures 2 and 3.
图4.: Time to Fuse - Time required for primary conductor to fuse open for vs. current.
直流电流能力
类似于响应各种大小和持续时间的高电流脉冲的差异，IC，PCB布局和应用程序组件的相同物理特性将影响器件处理连续电流的能力，并将管芯温度保持在165°C以下。将影响部分安全携带大的连续电流的另一个因素是环境温度。图5显示了测试的每个封装的管芯与DC电流的温度升高。这可以将其添加到环境温度中以便确定绝对模具温度，允许允许在模具超出到165°C的绝对最大值之前确定给定的环境温度的最大允许电流。例如，如果环境温度为45°C，并且通过ACS723LLC（LC2封装）的连续电流为50A，则封装内部的估计模具温度将达到115°C的稳态值（45°C环境温度+70°C的温度升高）。
图5.: Increase in Die Temperature vs. Current for Each Package Type
图6：每个包装类型的连续电流与环境温度
1For applications that require >50 A, refer toFifty to Four Hundred Amp Integrated Conductor Sensor ICs欲获得更多信息。
2演示板Gerber文件可在线提供，频率询问每个传感器的问题部分。