提高Allegro下一代高功率密度CB封装电流传感器的性能和特征
提高Allegro下一代高功率密度CB封装电流传感器的性能和特征
By Maxwell McNally
Allegro MicroSystems, LLC
抽象的
T.his 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.
Introduction
T.heACS772.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具有200 kHz的带宽增加，约80 kHz大于其前身的ACS770。ACS772不仅响应电流瞬变，而且通过专有补偿技术，它还具有更高的精度和最小漂移。该装置的相同引脚和操作允许将ACS772的替换为ACS770和ACS758插座。
CB封装和隔离
Internal to the CB package is a ferromagnetic concentrator that directs field from the current-carrying trace into the sensitive plane of the Hall element. Figure 1 indicates the different components that come together to form the CB package. Current travelling through the leadframe creates a magnetic field directed by the concentrator into the IC. The signal pins exit the overmolded package for connections to external circuitry.
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。要考虑ACS772的最小寿命漂移，设计了一种指定总输出误差漂移的新方法。ACS772指定一个T.otal Output
Error Including Lifetime Drift，消除了将漂移值添加到标称误差规范上。
ACS772在室温下的总输出误差减少0.9％，并且寿命约为2％小于ACS770。下表1比较了ACS772的总输出错误寿命值
those of the ACS770. It is important to note that the ACS770 is not specified in this way in the datasheet; a conversion has been made to the newer specification for easier comparison.
T.able 1: Total Error Specifications for ACS770 and ACS772
| T.otal Output Error | T.otal Output Error 包括寿命漂移 |
||||||
| T.emperature | DUT | Min. | 典型。 | 最大限度。 | Min. | T.yp. | 最大限度. |
| 25°C至 150°C |
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℃ |
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% | |
T.emperature Ratings
Allegro current sensor ICs have a maximum junction temperature (Tj（max）) of 165°C and all ACS772 devices are tested at the ambient temperature (TA）150°C。由于不违反最大结温度规范，因此设备可以在最大环境温度下安全运行。T.A对于持续的高电流应用中的器件降低值，因为预期电阻加热将内部温度更接近最大结温。亚博尊贵会员如表2中所述，这些温度代码直接出现在零件名称中
设备号码：ACS772LCB-050B-PFF-T。
T.able 2: Allegro Temperature Codes
| CB T.emperature Code |
额定Ta. (°C) |
当前的 感应 Range (A) |
Production Test T.emperature (°C) |
| L | –40 to 150 | ±100 | 150 |
| K | –40 to 125 | ±150 | 150 |
| E | –40 to 85 | ±200. | 150 |
Supply Voltage Levels
ACS772在Allegro上进行优化，并在生产中编程以在5V的电源电压下操作。ACS773以相同的方式优化3.3 V电源轨道。有关更多信息，请参考位于Allegro网站上的设备数据表。
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）。如果设备未正确供电，则输出将保持在地面。另外，如果电源电压降至另一个阈值以下（vUVLOL) for long enough (tUVLOE), 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具有电源复位（POR）。这在很大程度上以相同的方式，除了在低于低阈值时没有计时器。该装置立即关闭并进入高阻抗状态。
比例
T.he 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
T.he 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
| 规格 | 上升时间（μs） | 传播 延迟（μs） |
Response 时间（μs） |
| ACS772. | 2.4 | 1.2 | 2.5 |
| ACS770 | 4.1 | 2.4 | 4.6 |
| ACS758 | 3.0 | 1.0 | 4.0 |
噪音性能
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） |
rms.Noise （MARС） |
| ACS772. | 160 | 200 | 90. |
| 120[1] | 70 | ||
| ACS770 | 190 | 120 | 83. |
| ACS758 | 90. | 120 | 37 |
[1] Filtered to compare with lower bandwidth ACS770 and ACS758 devices.
T.he 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
CB封装中的Allegro下一代ACS772和ACS773器件提供更快的响应时间，并在整个寿命范围内更高的精度提高。这些传感器非常适用于需要这些下一变化改进的应用，并且提供亚博尊贵会员各种电流范围和电源电压，以满足任何应用需求。相同的封装和操作允许ACS772和ACS773成为Allegro ACS758，ACS759和ACS770器件的替代品。