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
亚历克斯·莱瑟姆和斯科特•米尔恩
亚博棋牌游戏
介绍
亚博棋牌游戏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。亚博尊贵会员对于高达亚博尊贵会员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:传感器C Comparison
Testing Performed and Limitations of Results
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。
| 包裹 | Conductor | 产品 |
| SOIC-8 | LC1：1.2MΩ | ACS711KLC |
| ACS712 | ||
| ACS713 | ||
| ACS714 | ||
| ACS715 | ||
| ACS724LLC. | ||
| ACS725LLC. | ||
| ACS730KLC. | ||
| ACS71240 | ||
| LC2: 0.65 mΩ | ACS7225LC. | |
| 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 |
Each package was subjected to the following tests:
| 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 | |
| DC Current Capability | 芯片温度与直流电流和环境温度 |
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。散热特性，特别是在中等电流（<150A）处，根据用于电流传感器IC附近的高电流迹线的PCB布局而变化。其他因素，例如PCBA是否用保形涂层封装（即，如果是“盆栽”）和PCBA被放置到的外壳会影响系统的热特性。本研究的目的是比较和对比上面列出的各种产品系列的相对性能，并概述当前每个包的电流水平和持续时间能够承受。应在将使用的特定应用条件下验证这些部件的高电流承载能力。
测试结果
高电流脉冲行为（保险丝特性）
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：
- The die can be damaged due to heat exposure, which can occur if the die is subjected to temperatures above165°C。
- The primary conductor will act as a fuse and open.
Figure 2 shows 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：LC1（SOIC-8）封装类型的保险丝和过温时间与电流
除了故障点，传感器IC保险丝的故障行为也很重要。通常，当集成导体保险丝时，导体的最薄部分分解，并且包装可能破裂。在所有测试中执行的所有测试中，当设备在过热之前融合时，故障不会导致设备的初级和次级之间的任何短路。但是，如果包装已损坏，则设备的隔离额定值将受到损害。
图3：安全操作面积 - 模具温度达到165°C或保险丝的时间（首先以其为准）。
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.
Figure 4: Time to Fuse - Time required for primary conductor to fuse open for vs. current.
DC Current Capability
Similar to the differences in response to high current pulses of various magnitudes and durations, the same physical characteristics of the IC, PCB layout, and application assembly will impact the device’s ability to handle continuous currents and maintain die temperatures below 165°C. The other factor that will impact the part’s ability to safely carry large continuous currents is the ambient temperature. Figure 5 shows the temperature rise of the die vs. DC current for each of the packages tested. This can be added to the ambient temperature in order to determine the absolute die temperature, allowing one to determine the maximum allowable current for a given ambient temperature before the die goes beyond the absolute maximum of 165°C. For example, if the ambient temperature is 45°C and the continuous current through an ACS723LLC (LC2 package) is 50 A, the estimated die temperature inside the package would reach a steady state value of 115°C (45°C ambient temp + 70°C temperature rise).
Figure 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
1对于需要亚博尊贵会员> 50a的应用，请参阅Fifty to Four Hundred Amp Integrated Conductor Sensor ICs想要查询更多的信息。
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。