Increasing System Safety using the A1365 Linear Sensor - yaboAPP亚博,yabo亚博网站,亚博电竞官网客户端

使用带自检诊断模式的A1365可编程线性霍尔效应传感器IC提高系统安全性

作者：Wade Bussing，应亚博尊贵会员用工程师，
Allegro MicroSystems, LLC

摘要

This application note provides guidelines for implementing the Self-Test Diagnostic mode on theA1365型从Alle亚博棋牌游戏gro MicroSystems，以验证应用程序中的系统功能和安全性。要从Allegro MicroSystems了解更多关于A1365的信息，请参阅位于的设备数据表www.wangzuanquan.com。

介绍

The advent of Automotive Safety Levels has spurred an increase in safety requirements, making IC and sensor safety features as important as the target performance specifications in some applications. As safety goals multiply throughout the system design process, customers demand smart sensors that can be used to diagnose abnormalities in a system. The built-in Self-Test mode of the A1365 grants users such insight into their systems.

A1365上的自检模式从模拟输出覆盖整个信号路径（V._出去)以及过错output pins up to the connections to the Hall transducer. Refer to the block diagram of the A1365 in Figure 1 which highlights the injection point of the on-chip test voltage in green.

A1365的自检模式允许用户在任何时候验证模拟信号路径的连接，在静态输出电压中漂移，以及通过现场故障信号路径的连接性和功能。通过比较自测试模式期间测量的电压和各种定时，用户还可以评估任何外部设备的完整性，包括系统ADC和过电流故障控制设备。自检故障特征简化了A1365外部的过电流故障电路的线路核实，而不会注入大全尺寸
currents.

自检模式旨在揭示霍尔路径中的严重单点故障，但不测试霍尔传感器本身的灵敏度。

启用自检模式

A1365 IC的所有销售版本都禁用了自检功能。然而，测试模式很容易启用使用Allegro A1365样本程序员和ASEK评估板。A1365示例程序员可在Allegro的软件门户网站https://registration.allegromicro.com。Contact your sales representative for information on acquiring an ASEK evaluation kit.

To enable the Self-Test mode on the A1365, power-on the device by pressing the “Power On” button[1]在A1365示例上，程序员如图2所示。确认设备正常工作
通过验证V_CC，我_CC, and Output values are reading as expected using the “Update” button[2].

**如图ure 2: Power Panel from the A1365 Samples Programmer**

编程器上的“内存”面板显示A1365设备上的所有可用寄存器，以及每个寄存器功能的简要说明[3]. Refer to Figure 3 for more information.

如图ure 3: Memory Panel from the A1365 Samples Programmer — 如图ure 3: Memory Panel from the
A1365型Samples Programmer

选择“全选”按钮[4],接着是“读取选定内容”按钮[5],它将读回设备的内存内容，并用返回的数据填充代码和值列。在对设备内存进行任何更改之前，最佳做法是保存EEPROM内容的本地副本以恢复到。选择“保存”按钮[6]生成.csv或.txt文件以进行安全保管。

要启用自检模式，请参阅图4.向下滚动到字段“st_dis”（自检禁用）[7],choose the “Deselect All” button [8], then select only the “ST_DIS” field using the checkbox. Set the “ST_DIS” code column to “0” by typing “0” into the cell, or choosing the “Zero Selected” button[9]on the GUI. When ready, press the “Write Selected” button[10]to write the new value to \ EEPROM. It is best practice to read back the same register to verify the change. Choose “Read Selected”[11]to confirm the “ST_DIS” bit has been cleared. The Self-Test mode is now enabled.

图4:A1365示例程序员的自检启用 — 如图ure 4: Self-Test Enable from the
A1365型Samples Programmer

启动自检模式

启用后，可以通过拉动A1365来启动自测试模式过错pin low. The device does not enter the Self-Test mode immediately; the过错引脚必须保持较低的时间段大于“自检开始时间”，才能进入自检诊断模式。自检开始时间可编程，并在编程字段“ST\ U Start\ U Time”中指定。有16个代码对应于12个离散的开始时间值。

表1列出了自检开始时间的可用代码及其相应的延时。

Self-Test Start Time is defined from when the过错引脚电压（V_过错)低于Self-Test Threshold Voltage (V_STTH) until the sensor enters the Self-Test Sense mode. The sensor enters Self-Test Sense mode by driving the analog output to Self- Test Low Voltage (V_STL). 如果在自检开始时间的任何时候，传感器检测到超过编程故障阈值的磁输入，自检定时器将复位。

The plot in Figure 5 shows the time for V_出去达到V_STLafter the过错pin is pulled low for all Self-Test Start Time codes on the A1365.

**如图ure 5: Self-Test Start Time for all Codes**

自检故障请求时间

Self-Test Fault Request mode allows the user to verify the userprogrammed fault thresholds on the A1365. The device will enter Self-Test Fault mode after the过错pin is released for a time longer than Self-Test Fault Request Time (ST_FR_TIME).

After the pin is released, but prior to Self-Test Fault Request time expires, the output is driven to Self-Test High Voltage (V_某事). 当设备进入自检故障请求模式时
驱动装置达到饱和（V_SAT(HIGH)).

表2中列出了自检故障请求时间（ST\u FR\u Time）及其相应延迟的可用代码。

In Self-Test Fault mode, the A1365 will drive V_出去into saturation, both V_SAT(H)和V._SAT(L). When V_出去crosses the user-programmed fault thresholds (FLT_THRESH), the sensor’s FAULT pin will assert to indicate a fault condition. Note that this mode temporarily disables the clamps if the clamps are enabled.

自检故障脉冲宽度时间

The A1365 will drive and hold V_出去to each test voltage for a period defined by Self-Test Fault Pulse Width Time (ST_FPW_TIME). The available codes for Self-Test Fault Pulse Width Time and their corresponding pulse width times are listed in Table 3.

Complete Self-Test Mode Sequence

The entire Self-Test mode sequence is shown in Figure 6. The applied magnetic field during the Self-Test Mode must be zero.

对于图6中的情况，ST\ U START\ U TIME=50 ms，ST\ U FR\ U TIME=10 ms，ST\ U FPW\ U TIME=10 ms。自检和磁故障设置如图7所示。

如图ure 7: Self-Test and Fault Settings for the Sequence in Figure 6 — 如图ure 7: Self-Test and Fault Settings
for the Sequence in Figure 6

自检顺序如下表所示。每个步骤对应于图7中绘图上的一个时间点。

A1365的过错引脚从外部拉低以启动自检模式。A1365此时仍能正确响应磁场。
The device enters Self-Test Sense mode after ST_START_ TIME and drives V_出去到V._STL.
V_出去保持在V_STL直到过错pin is released.
V_出去被驱动到V_某事对于自检故障请求时间的持续时间，ST\u FR\u Time。
设备进入自检故障请求模式，V_出去被驱动到V_SAT(H)在第一时间过错pin被断言。
V_出去被驱动到QVO进行ST\U FPW\U时间（10 ms）和过错pin重置。
V_出去被驱动到V_SAT(L)对于ST\ FPW\ U时间（10 ms）和过错pin被断言。
The Self-Test Sequence is complete and the device returns back to normal operation (mission mode).

应用案例

A1365上的自检模式可用于验证A1365设备上的严重异常和单点故障。此功能还可用于确认其他系统设备（包括adc和故障控制电路）的完整性和时序。

图8中的应用示意图示出了这样的系统。A1365安装在层叠芯的间隙中，并用于感测由导体中的电流流产生的磁场。模拟输出，VOUT连接到ADC过错pin is connected to a general purpose I/O pin on the microcontroller. Assume the I/O-connected过错引脚在发生过电流的情况下发出系统中断。该中断提示微控制器通过断开导体中的电流与电流的连接来将系统放置在安全状态。

**如图ure 8: Application Schematic with A1365, ADC, and Overcurrent Fault Control**