Allegro下一代高功率密度CB封装电流传感器的性能和功能得到了改进
Allegro下一代高功率密度CB封装电流传感器的性能和功能得到了改进
By Maxwell McNally
Allegro MicroSystems, LLC
摘要
This application note will describe the use of the new high-current ACS772 Hall-effect current sensor integrated circuit (IC) from Allegro MicroSystems and will give an overview of its features and improvements from previous Allegro high-current sensors.
介绍
TheACS772型is the newest in a long line of high-current measuring devices produced by Allegro MicroSystems. Housed in the Allegro proprietary CB package, the ACS772 offers ultrahigh power density, high inrush current capacity, and has factory-programmed options for sensing current in the range of 50 to 250 A. The CB package may be through-hole soldered directly onto the printed circuit board (PCB) which, along with the high isolation of the device, eliminates the need for expensive isolation techniques like optocouplers.
ACS772的带宽增加了200kHz，比其前身ACS770的带宽增加了约80kHz。ACS772不仅对电流瞬变响应更快，而且通过专有的补偿技术，它还具有更高的精度和最小的寿命漂移。该设备的相同引脚和操作允许将ACS772插入ACS770和ACS758插座。
CB封装和隔离
CB封装的内部是一种铁磁聚光器，其将场从承载迹线引导到霍尔元件的敏感平面中。图1表示将组成CB封装的不同组件。通过引线框架的电流产生由聚光器指向IC的磁场。信号销退出超模包以连接到外部电路。
总输出误差和Lifetime Drift
Calibration within application, when possible, can be costly and limited to a customer’s end-of-line production system. To this end, Allegro has designed the ACS772 to have the lowest lifetime
迄今为止任何CB电流传感器的漂移。为解决ACS772的最小寿命漂移问题，设计了一种新的总输出误差漂移确定方法。ACS772指定Total Output
包括寿命漂移在内的误差，无需在标称误差规格上添加漂移值。
ACS772在室温下的总输出误差比ACS770小0.9%，在使用寿命内的漂移比ACS770小约2%。下表1将ACS772的总输出错误生存期值与
ACS770的那些。值得注意的是，数据表中并未以这种方式指定ACS770；为便于比较，已将其转换为较新的规范。
表1：ACS770和ACS772的总误差规范
| 总输出误差 | 总输出误差 包括寿命漂移 |
||||||
| 温度 | DUT. | Min. | 类型。 | 最大值。 | Min. | Typ. | 马克斯. |
| 25摄氏度to 150℃ |
770 | –2.40% | ±1.5% | 2.40% | -4.30% | ±2.1% | 4.30% |
| 772 | –1.50% | ±0.9% | 1.50% | –2.10% | ±1.7% | 2.10% | |
| –40°C to 25摄氏度 |
770 | –3.50% | ±2% | 3.50% | –5.40% | ±2.6% | 5.40% |
| 772 | –3.50% | ±1.7% | 3.50% | –3.50% | ±2.6% | 3.50% | |
温度额定值
Allegro current sensor ICs have a maximum junction temperature (TJ（最大值）) of 165°C and all ACS772 devices are tested at the ambient temperature (TA)只要不违反最高结温规范，设备可以在最高环境温度下安全运行。T型A在持续的大电流应用中，电阻加热会使内部温度接近最大结温，因此会降低器件的额定值。如表2所述，这些温度代码直接出现在雷竞技最新网址零件名称的后面
设备编号：ACS772LCB-050B-PFF-T。
Table 2: Allegro Temperature Codes
| CB 温度 Code |
额定TA （°C） |
当前 传感 Range (A) |
生产测试 温度 （°C） |
| L | –40 to 150 | ±100. | 150 |
| K | –40 to 125 | ±150 | 150 |
| E | –40 to 85 | ±200 | 150 |
Supply Voltage Levels
The ACS772 is optimized at Allegro and programmed in production to operate at a supply voltage of 5 V. The ACS773 is optimized in the same way for 3.3 V supply rails. Reference the device datasheets located on the Allegro website for more information.
Having a device optimized for both 5 V and 3.3 V supplies allows the ACS772 and ACS773 family to replace any legacy device from Allegro, including the ACS758, ACS759, and ACS770.
Undervoltage Lockout
Undervoltage lockout (UVLO) prevents the ACS772 from operating outside of its optimized voltage range; it also gives diagnostic ability to the system about supply voltage drop. In order for the ACS772 and ACS770 to power-on correctly, the voltage must exceed a lockout threshold (VUVLOH) and stay above this level for a predetermined time (tUVLOD). 如果设备未正确通电，输出将保持接地。此外，如果电源电压低于另一个阈值（VUVLOL)足够长的时间UVLOE), the output will pull to ground and the part must be repowered. An output voltage of 0 V is outside of the expected range of the device and may indicate the sensor is operating outside of the supply voltage specification. This is implemented on the 5 V device (the ACS772).
3.3 V ACS773有一个上电复位（POR）。这在很大程度上是以相同的方式进行的，只是在低于低阈值时没有计时器。设备立即关闭，进入高阻抗状态。
比率法
The ratiometric output of the ACS772/3 scales in accordance with changes in supply voltage. Applications with an ADC referenced to the same supply voltage as the current sensor IC have reduced measurement error due to changes in VCC. The entire highcurrent portfolio of the ACS758, ACS770, and ACS772 have ratiometric outputs that provide this improved performance.
Bandwidth and Response Time
The ACS772/3 have an increased bandwidth of 200 kHz compared to the 120 kHz bandwidth of its predecessors. This allows the device to respond faster to current transients, which is highlighted in Figure 2, while the exact values of response time parameters are compared in Table 3.
表3：响应时间比较
| 规范 | 上升时间（μs） | 传播 延迟（μs） |
响应 Time (μs) |
| ACS772型 | 2.4 | 1.2 | 2.5 |
| ACS770 | 4.1 | 2.4 | 4.6 |
| ACS758型 | 3 | 1 | 4.0 |
噪声性能
It could be expected that higher bandwidth entails higher noise, but the ACS772 not only has an increased bandwidth but maintains similar noise performance to the ACS770. Table 4 below compares typical noise values and calculates both 200 kHz and 120 kHz filtered operation of the ACS772.
表4：噪声比较
| Part Number | 噪声密度 (μA / √Hz) |
Bandwidth （千赫） |
有效值Noise （马尔姆斯） |
| ACS772型 | 160 | 200 | 90 |
| 120[1] | 70 | ||
| ACS770 | 190 | 120 | 83 |
| ACS758型 | 90 | 120 | 37 |
[1]过滤以与下带宽ACS770和ACS758设备进行比较。
The noise of each device is best shown in Figure 3, where the noise densities are compared. Each of these devices were rated for 150 A with an identical gain of 13.33 mV/A.
结论
Allegro的新一代ACS772和ACS773设备在CB封装中提供更快的响应时间和更高的精度，在其整个使用寿命内的广泛工作温度范围内。这些传感器是理想的应用，需要这些下一代的改进，并提供了各种电流范围和电源电压，以满足任何应用需要。相同的包装和操作使ACS772和ACS773成为Allegro ACS758、ACS759和ACS770设备的直接替代品。雷竞技最新网址