Current Sensor FAQ

霍尔效应是当外部，垂直磁场施加到电流承载导体时的电压存在。导体或霍尔元件以恒定电流偏置。随着磁场的变化，霍尔元件两端的电压的变化发生。然后可以放大该电压并调节以提供与磁场有关的输出。使用该原理，可以使用集成包装，铁磁芯或无芯母线垂直于霍尔元件集中磁场。霍尔效应电流传感器具有固有隔离，低功耗和跨温稳定性的优点，同时提供可以由微控制器监控的模拟输出电压。

Parts can be ratiometric or non-ratiometric. Ratiometric indicates that the device sensitivity is proportional to the device supply voltage, VCC. In addition, the device output at 0 A, also called V_IOUT.（Q), is nominally equal tovcc / 2。Non-ratiometric devices will have VIOUT(Q) and sensitivity values stable over V_{科科斯群岛}在规定的输入电压范围内的变化。当传感器的输入电压与ADC参考电压在同一条线上时，比率测量法非常有用。非比例元件在传感器输入电压有噪声或不稳定的应用中非常有用。不稳定V亚博尊贵会员_{科科斯群岛}will produce a noisy output if the part is ratiometric.

当前传感器中的三种主要类型的错误被定义为：

灵敏度误差:E_SENS= (((Measured Sensitivity) / Sens) -1) × 100(%)

偏移错误：五_OE.=测量QVO–QVO

总输出错误：E_tot= ((V_OUT–五_理想)) / (Sens_理想的× I_P))× 100(%)

这application note更深入地讨论错误的来源和定义。

在Allegro Current Sensor device主页上，导航至“零件号规格和可用性”。在所需增益选项上选择“查看数据”。MSL评级包含在“材料申报报告”中。

虽然MSL评级专门用于表面贴装部件，但是Allegro确实有资格，并为非表面安装部件提供直接与标准MSL额定值相关的通孔等效（THD）。

One of the key benefits of Hall Effect current sensors is their inherent galvanic isolation. Because there is no electrical connection between the primary current path and the signal circuitry, much higher working voltages are available. There are several isolation parameters or tests included in the current sensor device datasheets such as:

电介质浪涌强度- The amount of voltage that can be handled of a pulse of known rise time, width, and amplitude.

介电强度- 发生在电击之前可以在电击前的电压和时间的量。这是在测量漏电流的同时测试一定的时间（通常为60秒），以确保未发生故障。

工作电压- 可以连续应用于设备的最大电压。它通常具有DC，峰值与峰值和RMS电压的指定值。

隔离特性是特定于设备的包装。以下是概述了Allegro提供的各种包装类型及其隔离特征以及其他重要的包信息表。

包描述符	SOICW-16. LA.	SOICW-16. 嘛	SOICW-16. 马克	SOIC-8 LC1.	SOIC-8 LC2.	QFN-12. EXB.	7针PSOF LR.	5针 断路器
Picture
Dimension	10.3x10.3mm	10.3x10.3mm	11.3x13毫米	4.9x6mm.	4.9x6mm.	3x3mm	6.4x6.4mm.	14x22mm
Conductor Resistance	0.85 mΩ	0.85 mΩ	0.27mΩ.	1.2mΩ.	0.65米Ω	0.6mΩ.	0.2米Ω	0.1 mΩ
介电强度	rms.3600 V.	rms.5000 V.	rms.5000 V.	rms.2400 V	rms.2400 V	NA.	NA.	rms.4800 V.
工作电压	直流870 V. rms.616 V.	直流1550V. rms.1097 V	直流1618 V rms.1144 V.	直流420 V rms.297 V.	直流420 V rms.297 V.	直流100 V rms.70伏	直流100 V rms.70伏	直流1358 V. rms.700 V.

Allegro also offerscore and coreless field sensors。这些设备可以感测电流> 1000A并实现> 5000VRM的介电强度隔离。

The part output will continue to increase or decrease until it reaches a high (current > IPR) or low (current < I_PR.）饱和点，在哪里_PR.是该部件的电流传感范围。电压输出高/低（v_哦/ V._ol.), sometimes referred to as Output Saturation Voltage (V_{坐（H / L）}), is defined as the voltage that sensor output, V_IOUT.，不会导致结果增加/降低电流。这可以在下图中看到。请注意，更改灵敏度不会改变饱和电压。

The functional range for the linear performance of V_IOUT.及其相关的数据表参数，来自-i有效_PR.to +I_PR.。输出可以报告超出全尺度测量的电压，直到饱和点，但不保证超出满量程测量的参数。

每个Allegro电流传感器都有数据表中规定的通电时间，例如以下示例：

上电时间，t_宝, is defined as the time interval between a) the power supply has reached its minimum specified operating voltage (V_{科科斯群岛（min)}）和B）当传感器输出在施加的磁场下稳定在其稳态值的±10％内。在下面的范围捕获中可以看到输出和电源电压的一个例子：

The磁铁、集中器和磁屏蔽供应商page on the Allegro website provides a vendor list and overview of recommended magnets. This list includes information on core/concentrator and shielding suppliers.

Allegro current sensors come in two range variants, bidirectional and unidirectional, which are identified with the part suffix B and U respectively. Bidirectional parts can sense positive and negative currents while unidirectional parts only sense in one direction. The output of a bidirectional parts will be at a minimum when current is full scale in the negative direction and at a maximum when current is full scale in the positive direction. The output of a unidirectional part will be at a minimum if current is less than or equal to zero and at a maximum when current is at full scale in the positive direction. Bidirectional parts are useful in detecting negative undershoot or beneficial to systems where current flows in both directions. Unidirectional devices can be used to increase sensitivity when there is no need to sense current in the negative direction.

每个Allegro电流传感器都包括用于V的引脚_{科科斯群岛}，地面（GND），V_出去，and a path for the primary current being sensed, if it is an integrated sensor. Some parts include additional pins for enhanced features. A list of these pins includes:

vref / vzcr-提供零电流输出电压（V._IOUT.（Q))连接到参考销。这允许差分测量和用户知道输出通道V的零电流电压_IOUT.. (ACS37002,ACS730)

FAULT /Over Current Fault (OCF)- open drain output that will pull low when a current threshold has been met. The fault output may be latched or unlatched in operation (ACS37002,ACS71240,ACS720型,ACS732,ACS733,A1365)

五_OC.- 某些部件可以使用外部电压选择过电流故障阈值。这是通过连接到V的电阻梯完成_{科科斯群岛}别针。（ACS37002,ACS720型,ACS732,ACS733)

获得选择- 某些部件可以根据应用于增益选择引脚的逻辑改变增益，用于查找高或低输入（ACS37002）。

过滤器- 通过连接外部电容，V_OUT滤波器位置可以设置（ACS720型,ACS724型/5)

噪音

噪音（input referred [mA_rms.] or output referred [mV_rms.])是在指定带宽下计算的输出噪声的均方根值。

噪音密度

噪音密度（input referred [(µA_rms.)/√Hz] or output referred [(µV_rms.）/√Hz]）是噪声作为频率的函数。大致从噪声密度转换为噪声，乘以噪声密度√（带宽*π/ 2）（请注意，在较低频率下，约<1kHz，闪烁噪声或1 / f噪声，起到一个因素，并将影响整体噪音performance, i.e. not all noise is removed with a DC input).

The resolution of the device is equivalent to the noise input referred [mA_rms.]在所需的带宽处。如果使用噪声密度指定设备，则通过乘以噪声密度来转换为噪声√(bandwidth*π/2)。如果设备被指定为引用的输出，则通过敏感性除以引用的输入。

Another factor to consider when calculating resolution is the capability of the ADC in which the current sensor output is connected. The ADC resolution of the sensor output in amps is equal to:

（ADC Range [mV] ) / ( Device Sens [mV/A] * 2^{ADC ENOB [bits]-1})

例如，计算分辨率ACS732KLATR-20AB-T在1MHz带宽下，使用有效位数为11.5的5V ADC。ACS732规定噪声密度为55(µA_rms.)/√Hz.

Multiply this value by √(1MHz * π/2) to get a noise of 69 mA_rms.，它给出了传感器输出的分辨率。

接下来，计算分辨率=的ADC分辨率（5000 mV）/（（100 mV）/ a *（2^11.5-1)）。

这导致ADC分辨率为34.5 mA。在计算系统的总分辨率时，取出这两个计算的最大值，或在这种情况下，69 mA。

Low pass filtering of the Allegro current sensor output will decrease the noise but at the cost of device bandwidth. If a specific noise level or resolution is desired, solve for bandwidth (BW) in the following equation:desired noise = noise density * √(BW*π/2)。

接下来，选择生成所需带宽的R和C值。RC滤波器的带宽等于1 / (2*π*R*C). 使用足够低的R值以不影响ADC读数是很重要的。因为ADC通常具有高输入阻抗，所以通常可以接受约1欧姆或更小的值。

• 验证数据表中的噪声如何。例如，噪声可能取决于V上的电容器_OUT，如下面的规格。

• 增加V的电容_OUT。数据表将包括可以连接到v的最大输出电容的值_OUT，如下面的规格。

• 如果更改电容无法解决问题，则应检查布局。如果是V._OUTsignal has a long trace to the ADC or measurement instrument, there may be other signals interacting with the output signal. Attach an oscilloscope as close as possible to the output of the current sensor and monitor the noise directly at the part output.
• 另一个潜在问题是传感器的不稳定输入电压。比率部件将对器件输出信号转移噪声输入电压。监控V._{科科斯群岛}电流传感器的引脚检查输入不稳定输入。确保正在使用正确的旁路电容值，并尽可能地放置在PCB上的部分。
• Another source of noise could be from stray magnetic fields.请参阅设计支持的问题1yabo亚博网站section了解缓解杂散领域。

Listed in the datasheet for each device is a Selection Guide, typically located on page 2 or 3. While there is some variation from device to device in what is included in the device selection guide, some primary attributes of the selection guide are the part number, sensitivity (Sens), optimized current range (only applicable to integrated conductor sensors), operating temperature (T_A), package type, and supply voltage (if the device has 5 V and 3.3 V variants). This table can be used as a guide when selection the current sensor for an application.

Examples:

基于核心（ACS70310)设备数据表中的选择指南：

有两个基本的allegro电流传感器命名方案，一个用于集成（ACS71240，ACS724，ACS37002等），一个用于基于核心的传感器（ACS70310，A1365等）。

Common naming components to integrated and core-based sensors: Allegro current sensors begin with ACS (with the exception of legacy A1363/5/6/7), followed by a three to five digit part number. The part number is followed by a letter to indicate the operating temperature range of the sensor. The temperature range designation is followed by the package designator, which can be two/three digits. Following the package designation, integrated sensors then have a two letter designation for available packaging/shipping options and core-based sensors will have a two letter designation for the leadform option. Next, integrated sensors have a two/three digit current range value and the core-based sensors have the trimmed sensitivity value. This is then followed by the sensor’s directionality, bidirectional (B) or unidirectional (U). Next is the device’s nominal supply voltage level. Included at the end of the part name are custom features (custom fault level, set polarity, customer programmable, etc.). See the device specific datasheet for more information about the device’s part number. Note that legacy devices, like the ACS722/ACS723, ACS724/ACS725, and ACS732/ACS733, do not have a bidirectional or unidirectional designation in the name nor do they have a designation for nominal supply voltage. Different part numbers were made for 3.3 V and 5 V variants (i.e., the ACS724 is a 5 V device while the ACS725 is a 3.3 V device but these parts have identical functionality).

Examples of Naming Schemes:

基于核心（ACS70310）：

融合的 （ACS71240）：

遗产集成（ACS724型vs.ACS725型，请注意选择指南中没有电源电压指示）：

A min/max limit guarantees that no devices will be above or below the min/max value when leaving the Allegro factory. Typical values are mean ± 3 sigma. This means that 99.7% of devices will fall within the typical values and none will fall outside the min/max limits within the specified operating temperature range, input voltage, or any other test conditions.

It is also important to note that Sensitivity Error (ESENS) and Total Error (ETOT) are specified at a given current (typically the full-scale current, or half-scale current). Error results may vary with different applied currents. The main example of this is Total Output Error at lower currents. For example, if the full-scale range of a part is 20A and there is a 5% maximum Sensitivity Error and 1A maximum Offset Error, maximum Total Output Error = 20 A * (5% / 100) + 1 A = 2 A or 10% of the full-scale applied current of 20 A. At 5 A applied with the same sensitivity error and offset, Total Output Error = 5*(5% / 100) + 1 A = 1.25 A or 25% of the full-scale applied current.

以下 application noteprovides characterization data for the Allegro current sensor packages. This application note includes data taken on Allegro demo boards. This document is useful when deciding the correct Allegro current sensor package for a given application and current requirement.

可以流过包装的绝对最大电流量与设备可以感测的电流范围不同。最大允许电流取决于封装和PCB布局，是环境温度的函数。参考常见问题解答热部分的问题1有关确定Allegro电流传感器最大允许电流的信息。当流过电流大于优化电流传感范围时，设备的输出将饱和。参考Question 7 of the General Section of the FAQ有关输出饱和度的进一步解释。

A– Allegro
S– Sensor
E–评估
K- 成套工具

导航到Allegro Micro亚博棋牌游戏systems主页. Allegro电流传感器演示板以“ASEK”名称开始。例如，如果需要ASEK37800KMAC‐015B5‐SPI演示板来评估ACS37800KMACTR-015B5-SPI，请在Allegro主页右上角的“Check Stock”搜索栏中搜索ASEK37800。

搜索“ASEK37800”将为所有可用的ASEK37800演示板提供结果。点击购物车图标被路由到Digikey网站以进行购买。

在“设备主页”上，单击“设计支持工具”的链接，如下图所示：yabo亚博网站

如果演示板有一个用户指南，它将在设计支持工具中提供可下载链路，如下所示：yabo亚博网站

演示板上的所有组件将在测试的电流传感器的最大温度额定值处额定值或高于测试。演示板的当前额定值取决于电流传感器和环境温度的包装。以下application note提供各种环境温度的Allegro演示板上的电流传感器包的特征数据。

在每个Allegro电流传感器的设备主页上都有一个设计支持部分，位于网页底部附近。这里有一个zip文件，其中包含设备的yabo亚博网站ASEK演示板的Gerber文件。Gerber文件是包含PCB设计的每个板层信息的文件。

解压缩Gerber文件文件夹后，将有一个Fab文件。该FAB文件包含有关演示板布局的信息以及关于铜厚度，PCB层计数的信息，包括演示板属性。

在每个设备数据表中，有一个PCB布局和热应用部分，特定于该设备和包。

相关申请说明：

1. Managing External Magnetic Field Interference When Using ACS71x Current Sensor ICs
2. 使用Allegro电流传感器IC时最小化共模场干扰的技术（ACS724和ACS780）
3. Common Mode Field Rejection in Coreless Hall-Effect Current Sensor ICs

参考Question 1 of the Design Support FAQ section了解缓解杂散领域。

在特定的Allegro当前传感器设备主页上，导航到“部件号规范和可用性”。在所需的增益选项上选择“查看数据”。包重量包含在“材料申报报告”中。

在位于网页底部附近的所需Allegro电流传感器的设备主页上，是一种包装部分。在包装部分中，通常存在包装的封装图像（如果设备在多个包中提供），则设备被容纳在（多于一个）。可以在此处找到设备包的步骤文件。

如果步骤文件未位于设备主页上，请参阅包装主页on the Allegro website.

获取UL认证表明Allegro当前传感器已被测试到适用标准;UL在全球范围内得到认可，他们能够为行业的制作提供认证。Allegro当前传感器，位于MA，LC，MC，LA和CB封装中，已被认证到相关的UL标准60950-1，第2版和62368-1，第1版（仅限MA）。

位于device homepage of Allegro Current sensors housed in the MA, LC, MC, LA, and CB packages are the UL Certificates of Compliance and UL CB Test Certificates.

符合性证书验证设备已由UL按照UL标准60950-1和UL标准62368-1（仅限MA）进行测试。CB测试证书提供了UL认证的基本和加强绝缘数的工作电压以及最大额定隔离电压。

参考“Soldering Methods for Allegro Products”关于Allegro网站的应用笔记和下载了这里。

• LA具有最接近导体的霍尔元件的最高敏感性
  • 填充芯片位于最接近引线框架的模具顶部
• MA具有高内部隔离
  • 2层聚酰亚胺绝缘和3层绝缘粘合剂
• 马克has the lowest internal conductor resistance
  • 更长的爬电以更好的工作电压

另请参阅一般问题部分的问题6of the FAQ for more package information.

There are several ways to begin the product selection flow. The first would be based off the required isolation or package size. The following table provides an overview of the available packages (not including field sensors).

包描述符	SOICW-16. LA.	SOICW-16. 嘛	SOICW-16. 马克	SOIC-8 LC1.	SOIC-8 LC2.	QFN-12. EXB.	7针PSOF LR.	5针 断路器
Picture
Dimension	10.3x10.3mm	10.3x10.3mm	11.3x13毫米	4.9x6mm.	4.9x6mm.	3x3mm	6.4x6.4mm.	14x22mm
Conductor Resistance	0.85 mΩ	0.85 mΩ	0.27mΩ.	1.2mΩ.	0.65米Ω	0.6mΩ.	0.2米Ω	0.1 mΩ
介电强度	rms.3600 V.	rms.5000 V.	rms.5000 V.	rms.2400 V	rms.2400 V	NA.	NA.	rms.4800 V.
工作电压	直流870 V. rms.616 V.	直流1550V. rms.1097 V	直流1618 V rms.1144 V.	直流420 V rms.297 V.	直流420 V rms.297 V.	直流100 V rms.70伏	直流100 V rms.70伏	直流1358 V. rms.700 V.

其他产品选择流可以从所需的电流传感电平开始。Allegro为各种电流传感级别的登陆页，包括：

• 0-50A传感器
• 0-400A电流传感器
• 0 to >1000A Field Sensors

The目前的传感器创新还强调了不同产品系列的好处。

调试杂散磁场时，检查传感器是否是单个或双霍尔技术，通过检查设备特定数据表的功能框图。

单堂和流浪领域：

Because Allegro current sensors use the Hall Effect to measure current, any additional magnetic field seen at the hall element outside of the current being measured will affect the output of the sensor. These additional magnetic fields are generally called stray or common magnetic fields. The most common cause for stray magnetic fields is the presence of a high current trace or wire near the current sensor. To approximate error caused by a current carrying wire, model the magnetic field of the trace as an infinite wire whereB=µ* (一/（2）π×d） （）。

Bis the magnetic field in Gauss (G),µ是g等于自由空间的渗透性4π* 0.001,Iis the current in amps, andd是米的距离的线从一个点吗on the wire to the hall element perpendicular to the wire. Once the magnetic field is known, multiply by the magnetic coupling factor [G/A] (provided in most datasheets) which will result in an absolute error in amps. Once error is estimated, testing can be performed by removing the stray field generating wire or trace and retesting the sensor output. Another solution if the trace or wire cannot be removed is to pull the sensor off the board and wire the part off the PCB away from the suspected current carrying wire. Lastly, shielding can be utilized by placing a ferrous material around the sensor to block the stray field.

这application notedescribes in more detail the effects of magnetic field interference and shielding.

双厅和杂散场：

Allegro还提供带有双霍尔元件的传感器，以减轻杂散场误差。两个霍尔元件被区别地使用，并放置在电流回路的相对侧。这样可以消除公共磁场，使输出电压显著不受公共磁场的影响。虽然双霍尔元件可以减小杂散场误差，但并不能完全消除杂散场引起的误差。在调试双霍尔传感器时，也可以使用上一段中相同的测试/缓解技术。

这application noteexplains in more detail how to estimate and mitigate common magnetic field when using sensors with dual hall elements.

Allegro provides LTSpice models for most Allegro current sensors. The following我inkwill download a zip folder with the entire library of spice models for Allegro current sensors. Read “ALLEGRO_ACS_LT_Guide.pdf” included within the zip folder for a detailed walk through on how to get started and how to use Allegro parts in LTSpice.

这note提供使用母线设计的概述，指导和仿真结果。

Allegro还提供online interactive modeling too我to help design bus bars for coreless solutions.

这noteprovides an overview and guidelines for designing a core/concentrator to pair with Allegro field sensors.

以下is a check list to follow to verify the proper output of an Allegro current sensor:

• 输入电压高于最小和低于数据表中指定的最大值吗？调整输入电压以匹配数据表中的典型VCC值。
• Does the input current match the typical on the datasheet? If the current is lower than expected, there may be an open circuit between the input supply and the sensor. If current is higher than expected, there may be something else on the input sinking current and preventing the device from biasing properly. Verify the supply hookup to the part.
• When the device is biased on correctly, but no current is applied, what is the output of the device? Ensure that when in this state, the device output matches the zero-current output voltage (V_IOUT.（Q)）在数据表中指定的）。如果这不匹配，请测量从输出到地面的电阻，并确保没有任何拉动输出低。另外尝试将传感器转发或用另一部分替换，以查看问题是否仍然存在。这将验证问题是否是零班或应用程序。
• 如果V._IOUT.（Q)is normal, is the sensitivity of the device within the datasheet specification? To quickly test sensitivity, apply 0 A and measure V_IOUT.，然后应用已知的电流和remeasure v_IOUT.。这两点的斜率是MV / A中的灵敏度。要解决灵敏度的问题，请确保所感测的电流路径的电阻是通过用欧姆计测量来预期的。焊接故障或杂散迹线可能通过测量和引入误差的导体降低电阻。

其他潜在问题包括噪音（请参阅常见问题解答的“噪音”部分）和杂散磁场（请参阅常见问题解答的设计支yabo亚博网站持部分）。

基本上，每个分路解决方案都可以用集成霍尔效应传感器代替，只需将电流轨迹通过集成电流传感器，而不是通过外部分路即可。为数不多的分流解决方案可能不适用于集成霍尔效应传感器，包括超低电流分辨率（在uA中）或超高速（>1Mhz）。

从分流器解决方案到集成霍尔效应解决方案的关键优势是增加的隔离，降低的布局大小，并且设计复杂性降低。在不使用需要外部隔离电路的隔离放大器的情况下，大多数分流器解决方案不能超过100多V共模电压。将其与霍尔效应电流传感器进行比较，从而从电流路径到信号引脚的固有隔离。切换到霍尔效应传感器还消除了外部分流器和输入滤波的需要。这降低了布局空间以及设计复杂性。

有很多方法可以测量系统中的电流，但下表突出显示并比较了主电流传感解决方案：

位于Allegro客户门户是程序员GUI / DLL，适用于Allegro客户可编程传感器。除了用于客户可编程设备的编程软件外，Allegro客户网站还有有用的设计工具，包括用户指南和交互式设计工具。

TheASEK20is a device used to program and evaluate customer programable Allegro current sensors (the ASEK20 can be used for angle position, linear position, and digital position sensors). The ASEK20 is used in combination with the device specific daughterboard (which are available separately from the ASEK20). The ASEK20 is a benchtop validation and programming tool useful in characterizing and understanding the performance of Allegro current sensors. The ASEK20 is also useful in calibrating Allegro current sensors in the field. Device specific software applications can be found onAllegro’s Software Portal。

Customer Programable Allegro Current Sensors that can be used with the ASEK20:

1. ACS70310
2. ACS70311
3. ACS71020
4. ACS37800.
5. A1363
6. A1365
7. A1367

请参阅“'rohs'是什么意思？”发现在质量与环境常见问题。

请参考质量与环境常见问题。

导航to the质量标准和环境认证Allegro网站主页。在标题为“政策和宣言”，有一个标题的声明和陈述部分。在这里，可以找到RoHS合规声明。