Quality Standards and Environmental Certifications

ACS758电流传感器IC常见问题

The differences are the output sensitivities (in mV/A) of each version and their operating temperature ranges. Operating temperatures are also related to maximum current ranges.
Externally, the packages are identical and have the same footprint. Internally, the CB package leadframe has greater cross-sectional area where the conductor passes the Hall-effect device. As a result, the CB package conductor has a resistance of only 100 µΩ, versus 130 µΩ for the CA package. In addition, the CB core is made of laminated steel and has a much higher saturation point (at higher temperature) than the ferrite core inside of the CA package.
是的。ACS758系列使用霍尔效应技术，能够感测具有DC和AC部件的电流。作为数据表状态，ACS758的带宽为120 kHz典型。对于具有大于120kHz的频率内容的AC电流，可以存在阶段滞后和幅度衰减。对于瞬态电流信号，响应时间为≈4μs。
不,在传感范围的最大电流e ACS758 is an absolute current of 200 A. The magnetic circuit within the ACS758 package will not provide a linear output above field levels generated by 200 A.
This feature is particularly valuable when using the ACS758 with an analog-to-digital converter. A/D converters typically derive their LSB from a reference voltage input. If the reference voltage varies, the LSB will vary proportionally. The ratiometric feature of the ACS758 means its gain and offsets are proportional to its supply voltage, VCC. If the reference voltage and the supply voltage for the ACS758 are derived from the same source, the ACS758 and the A/D converter will both track those variations, and such variations will not be a source of error in the analog-to-digital conversion of the ACS758 output. Figure 1 is a plot of primary current, IP, versus output voltage, VOUT, of the ACS758-100A when varying VCC. The offset and sensitivity levels shift proportionally with VCC. For example, when VCC = 5.5 V, the 0 A output is 5.5 / 2 = 2.75 V nominal, and the sensitivity is 22 mV/A nominal.
figure 1


图1. ACS758-100A VOUT与IP各种VCC
Allegro建议在VCC引脚和GND引脚之间使用0.1μF旁路电容。电容器应与ACS758封装体一样靠近。
No, the ACS758 sensitivity and 0-ampere (quiescent) voltage level are programmed at the factory.

The current resolution of the ACS758 family of current sensor ICs is limited by the noise floor of the device output signal. For example, the ACS758-050 version can resolve a change in current level of about 250 mA, at 25°C, through its primary conductor leads. The 200 A version can resolve approximately 380 mA. At these levels, the amount of magnetic field coupled into the linear Hall-effect IC is just above its noise floor. Resolution can be improved significantly by filtering the output of the ACS758 for applications requiring lower bandwidth. Table 1 lists the noise levels, and hence current resolutions, at various bandwidths. Filtering was accomplished with a simple, first order RC filter. Note the related graphs, figures 2 through 5, which provide a better understanding of the device output resolution that can be achieved through filtering.

Table 1. ACS758 Noise Level and Current Resolution versus Bandwidth
Device Bandwidth -3 dB
(kHz)		 Noise
(mVp-p)		 当前的解决方案
（嘛） (% of full scale)
ACS758-200B 120. 3.84 384. 0.。192
10. 0.。92 92 0.。0.46
1 0.。55 55 0.。0.28
0.。2 0.。15. 15. 0.。0.0.8.
ACS758-150B 120. 4.36 328 0.。219
10. 1。0.8. 8.1 0.。0.46
1 0.。52 39. 0.。0.26.
0.。2 0.。16 12. 0.。0.0.8.
ACS758-100B. 120. 5.69 285 0.。285
10. 1。49 75 0.。0.75
1 0.。67 34. 0.。0.34.
0.。2 0.。22 11. 0.。0.11
ACS758-50B 120. 10.03 251. 0.。502
10. 2.95 74 0.。148
1 1。0.5 26. 0.。0.53
0.。2 0.。43 11. 0.。0.22

图2A
图2A

图2B.
图2B.


图3A
Figure 3A


图3B.
Figure 3B


图4A
Figure 4A


图4B.
Figure 4B


figure 5a
Figure 5A


figure 5b
Figure 5B

Typical ESD tolerance is 6 kV human body model, 600 V machine model.
为了安全地进行200个电流，ACS758中的电源引线已经构造成具有相对较重的规格。由于这种重型计，终端引线不是很柔韧。如果ACS758被表面安装，少量的电路板弯曲或随着热膨胀时间和收缩时间的动作可能会使电路板断开IC。Allegro不建议该设备的表面安装组件。
To ensure a robust joint to the board, Allegro recommends adding a ring of through-holes in the solder pad area around each of the two broad primary conductor leads that carry the current being sensed. These holes are shown in figure 6. General soldering recommendations for the CA and CB packages have been added to the application note "Soldering Methods for Allegro's Products (SMD and Through-Hole)“。
Allegro recommends a tin-fusing welding technique. This method is described in our application note "Guidelines for Designing Subassemblies Using Hall-Effect Devices“。
Yes, figure 6 shows the recommended footprint for the –PFF leadform configuration. The portion (A), specifically the three small through-holes for the signal pins, also applies to the –PSF configuration (which has straight primary conductor leads).
figure 6
Figure 6. ACS758 PFF configuration recommended PCB layout
是的，下载：Allegro_ca_cb_evalboard.(ZIP).
Yes, an AutoCAD 2004 .DXF file can be downloaded from:Allegro_ca_cb_evalboarddxf.(ZIP).
The copper areas are defined as "regions" in these files.
The evaluation board uses 4–oz. copper.
The temperature of the primary current path terminals can be used to estimate the temperature of the die inside the package. As can be seen from figure 7, the temperature on the sides of the primary current path terminals, close to the package case, will be at almost the same temperature as the primary current path bridge inside the package. The die inside the package will be approximately 1°C below this temperature. In order to measure the temperature inside the package, solder a thermocouple in either of the locations shown in figure 8. Then, subtracting 1°C gives a very good estimate of the die temperature. The die temperature should be kept within the range specified in the datasheet for the version of the ACS758 that is being used.
热剖面
Figure 7. Temperature profile of primary current path


solder points
图8. ACS758包装顶视图，带热电偶位置
应注意尽量减少要测量的电流路径的电感。此外，应注意最小化主要路径中任何连接的接触/连接电阻。
Typical measured inductances versus test signal frequency are:
  • 在10 kHz的32 nh
  • 24 nH at 100 kHz
  • 200 kHz 21 nh
No, the ACS758 family is lead (Pb) free. All of the signal pins and terminals are plated with 100% matte tin, and there is no Pb inside the package.
The heavy gauge leadframe is made of oxygen-free copper.
ACS758包含一个集中器核心，该核心不仅作为IP产生的磁通线的集中器，而且作为保护霍尔电路IC免受环境共模字段的屏蔽（典型的共模字段为-41 dB）。结果如图7所示，比较非屏蔽线性霍尔效应传感器IC的输出电压Vout和ACS758的输出电压Vout。该装置具有相同的增益，并且暴露于相同的磁场，通过包装的顶部施加在空气芯中。
figure 7a
Figure 7. ACS758 performance in stray magnetic fields
ACS758系列已通过承销商实验室认证，以以下标准：
  • IEC 60950-1：2001，第一版
一世n addition, the ACS758 family has been certified by TÜV America to the following standards:
  • UL 60950-1：2003
  • EN 60950-1:2001
  • CAN/CSA C22.2 No. 60950-1:2003
The mold compound is UL recognized to UL94V-0.
The typical output behavior of the ACS758xCB-050 during a 500 ms ramp-up of VCC is shown for both 0 A and 50 A in figure 8:

figure 8a
Figure 8A. ACS758 power-on performance. VCC ramp-up with IP = 0 A
5 V / 500 ms转换速率;C1：VCC = 2 V / div。，C2：Vout = 2 V / div。，时间= 50.0 ms / div。


figure 8b
Figure 8B. ACS758 power-on performance. VCC ramp-up with IP = 50 A
5 V / 500 ms转换速率;C1：VCC = 2 V / div。，C2：Vout = 2 V / div。，时间= 50.0 ms / div。
The typical time to valid output is given in table 2 and figure 9. However, we recommend a 3x to 5x safety margin to account for power-on time variation over process and temperature ranges.

Table 2. ACS758 Time to Valid Output
(Measured at VCC.= 5 V)
一世P.（一种） 0. 50
上电时间（μs） 8. 10.

figure 9a

Figure 9A. Startup of ACS758-50A with 0 A applied, then a VCC step from 0 to 5 V
5 V / 500 ms转换速率;C1: VCC = 2 V / div。C2:输出电压= 2 V/div., time = 10 µs/div.


figure 9b
图9B。ACS758-50A的启动有50 A应用，然后VCC步骤从0到5 V
5 V / 500 ms转换速率;C1: VCC = 2 V / div。C2:输出电压= 2 V/div., time = 10 µs/div.
传感器IC的输出可以振荡。
The sensor IC may not produce an output, as its output driver will not be able to supply sufficient current.
由于其低，100μΩ的内阻，ACS758传感器IC的CB封装的过电流能力高度依赖于安装在其上的汇流条或印刷电路板的特性。在PCB安装，迹线宽度和厚度的情况下，层数，接地和/或电源平面的缺失，以及携带电流的电缆的仪表的尺寸是所有重要因素。它还取决于应用程序的最大工作温度以及过流事件期间的持续时间，占空比和当前脉冲的数量。举例来说，我们在Allegro ACS758评估板上表现了ACS758器件，连接到带有2个AWG电缆的电流源。这款带4盎司的2层板。铜。
The results are provided in Table 3.

Table 3. Tested Maximum ACS758 Overcurrent Levels and Durations
(Applicable to devices on Allegro ASEK 758 evaluation boards connected with 2 AWG cables)
Ambient Temperature
(°C)		 Maximum Current
（一种）
10 S，10％占空比，100脉冲施加
25. 350.
8.5 350.
15.0. 260.
3 s, 3% duty cycle, 100 pulses applied
25. 450
8.5 425
15.0. 375.
1s, 1% duty cycle, 100 pulses applied
25. 120.0.
8.5 900
15.0. 600
The lead frame noise rejection test is conducted by injecting a high-frequency sinusoidal frequency onto the high-current leads. The signal coupling onto the output of the Hall-effect device is then measured. The ACS758 family devices exhibit a high level of leadframe noise rejection as table 4 reveals. In addition, the figure 10 charts performance as a function of frequency.

Table 4. Typical Capacitive Coupling of a 20 V Peak-to-Peak Signal on the Current Path
f (MHz) 1。0. 2.0 3.0 4.0 5.0 7.5 8.。5 10.0 15.。0. 18.0 20.0
V.OUT(p-p)(mV) 15.。0. 50.0 10.0.。0. 200.0 250.0 700.0 750.0 1000.0 1020.0 1050.0 600.0
Noise Rejection (dB) -62.5 -52.0 -46.0 -40.0 -38.1. -29.1 -28.5 -26.0 -25.8 -25.6 -30.5.

流浪磁性
Figure 10. ACS758-50A Noise Rejection versus Frequency

是的，下载：CA/CB Package .stp model