Quality Standards and Environmental Certifications

ACS709电流传感器IC常见问题

The ACS709 current sensor family has the following advantages:
  • 用户可调过电流故障电平
  • 高速过电流故障响应（<2µs）
  • Wide bandwidth of 120 kHz
  • Low noise, hence better current resolution
  • Small footprint surface mount QSOP24 package
  • High isolation voltage allows high working voltage
  • Wide ambient temperature range for automotive applications
“优化精度范围”，IPOA，是目前的范围内，修剪的ACS709是在工厂进行。ACS709在整个线性传感范围（IR）内几乎同样精确。
Yes. Just connect the FAULT_EN pin to the /FAULT output pin (shown as A in figure 1), to achieve automatic Fault reset. This configuration makes the circuit function as a current comparator. (See the oscilloscope plot in figure 2 for the input and output signal waveforms.) A capacitor, COC, is recommended to avoid any possible glitches at the /FAULT pin. It should be of appropriate value, usually greater than 1 nF, dependent on the noise environment and the Fault response time required.

图1。在A点的连接可实现过电流故障的自动复位。
输入输出波形
图2。ACS709的输入（IP-）和输出（故障）信号波形
配置如图1所示，COC=100 nF。
Yes. The ACS709 family uses Hall-effect technology, which is capable of sensing electrical currents having both DC and AC components. As the datasheet states, the bandwidth of the ACS709 is 120 kHz typical. There may be phase lag and amplitude attenuation of the output for AC currents with frequency content greater than 120 kHz. For transient current signals, the response time is ≈ 4 µs.
这个特性是使用t时特别有价值he ACS709 with an analog-to-digital converter. A-to-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 ACS709 means its gain and offsets are proportional to its supply voltage, VCC. If the reference voltage and the supply voltage for the ACS709 are derived from the same source, the ACS709 and the A-to-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 ACS709 output. Figure 3 is a plot of primary current, IP, vs output voltage, VOUT, of the ACS709-35BB 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 30.8 mV/A nominal.
输入与输出
图3。ACS709-35BB输出电压对一次电压
感应电流，在不同的电源电压水平。
Allegro recommends the use of a 0.1 µF bypass capacitor between the VCC pin and the GND pin. The capacitor should be located as close as practicable to the ACS709 package body. Use of other external components depends on the application; please refer to Typical Application section of the datasheet.
No, the ACS709 sensitivity and 0-ampere quiescent voltage level are programmed at the factory.
The current resolution of the ACS709 family of sensor ICs is limited by the noise floor of the device output signal. For example, the ACS709-20BB version can resolve a change in current level of about 160 mA, at 25°C, at full bandwidth. The ACS709-35BB version can resolve approximately 210 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 ACS709 for applications requiring lower bandwidth. The noise level will, to the first order, scale proportionally with the square of the frequency. This means that the noise at lower bandwidths for the ACS709-20BB, can be approximated to be:
C级urrent resolution equation
Using the equation given above, table 1 gives resolution values for different filter capacitor values, CF, which forms a first order RC filter with the internal resistor RF(INT) (typical value 1.7 kΩ).

Table 1. ACS709-20BB Noise Level and Current Resolution
对滤波电容和产生的带宽

C级F级
（纳法）

体重
(kHz)

五RMS噪声
(µV)

五P-P公司噪声
(µV)

当前分辨率
（毫安）

0

120

1500

9000

161

1

94

1327

7966

143

2.2

43

898

5387

96

4.7

20

612

3674

66

10

9

411

2465

44

22

4

274

1643

30
典型的ESD耐受性为6kV人体模型和600V机器模型。
ACS709载流导体和传感器接地之间的电容约为2 pF。
不，ACS709系列是无铅的。所有引脚都镀有100%亚光锡，封装内没有铅。
有，下载地址：ACS709 Gerber Files（ZIP）。
Yes, a layout drawing PDF file can be downloaded from: ACS709 Layout Drawing (PDF).
Assumptions:
A. The current carrying conductor is on the same plane as the Hall element, and
B. The conductor has an infinite length
基于上述假设的结果将是最坏情况下的结果，即载流导体产生的杂散场对霍尔元件的影响。
The magnetic field generated in the direction perpendicular to the plane in which the conductor and the Hall element lie, at the distance l to the conductor will be:
Β = µ × I ⁄ (2π × L) (tesla)
在哪里？
µ=µ0=4π×10-7（H/m）=400π（nH/m），假设周围没有芯材，
I的单位是安培，即在导体中流动的电流，和
L is in meters, the distance between the point under consideration and the conductor.
分析的依据是ACS709系列的磁耦合系数通常为9.5高斯每安培（0.95mt/A）。
图4中的图表显示了与霍尔元件位于同一平面的载流导体在不同距离处引起的绝对电流误差。相对于全量程的百分比误差可计算为：
Err = (absolute current error ⁄ IP) × 100 (%)
绝对电流误差
F级igure 4. The absolute current error versus separation distance for various current values.
ACS709系列已通过UL认证，符合以下标准：UL1577。

The mold compound is UL recognized to UL94V-0.
ACS709-20BB在VCC缓慢上升期间的典型输出行为如图5中的0 a和图6中的12.5 a所示。

Slow Vcc ramp at 0 A IP

图5。IP=0 A时VCC上升。
Slow Vcc ramp at 12.5 A IP
图6。IP=12.5 A时VCC上升。
The typical time to valid output is given in table 3 and in figure 7 (IP = 0 A, VCC = 5 V) and figure 8 (IP = 12.5 A, VCC = 5 V). However, we recommend a 3X to 5X safety margin to account for power-on time variation over process and temperature ranges.

Table 3. ACS709-20BB Input Current versus Power-On Time

我第
（一）

t型第O
（微秒）

0

14

12.5

16
在0 A IP启动
F级igure 7. Startup of ACS709-20BB with 0 A applied, then a VCC step from 0 to 5 V.
12.5 A IP启动
F级igure 8. Startup of ACS709-20BB with 12.5 A applied, then a VCC step from 0 to 5 V.
ACS709-35B从深度饱和开始的VIOUT响应时间的测量值小于9µs。有关详细信息，请参见图9中的示波器图。
从饱和状态输出
F级igure 9. Test conditions: for saturation, VCC = 5 V, TA = 25°C,
我第= 180 A; for linear VIOUT, Ip = 40 A.
图10中的图表显示了ACS709电流传感器IC电路的高电平频率响应模拟结果。上面的图是振幅响应，下面的图是相位响应。
频率response
F级igure 10. Frequency response of the ACS709.
The output of the sensor may oscillate.
The ACS709 may not produce an valid output, because the output driver will not be able to supply sufficient current.
The following overcurrent limit results are based on the Allegro ASEK709 evaluation board. The limits may be different on a different application board. For detailed information on the Allegro ASEK709 evaluation board, please see FAQ Can I get the Gerber files for your evaluation board?.
Table 4 presents results for continuous DC current, and table 5 presents results for pulsed current. Figure 11 shows the effects of various input current levels on die temperature.

Table 4. Continuous Current Overcurrent Limits
ASEK709评估板，在各种环境温度下

t型A
(°C)

我P（奥克林）
（一）

25

50

85

40

125

25

150

20


表5。脉冲电流过流限值
ASEK709评估板，室温下

我第
（一）

持续时间
（毫秒）

Duty Cycle
(%)

Quantity of
允许的脉冲

100

1000

NA

Single

100

300

30

20

150

200

NA

Single

150

100

10

20

200

50

NA

Single

200

20

10

20
模具温度
F级igure 11. ACS709 die temperature (°C) versus continuous DC IP current (A)
一组ACS709-20BB设备的分布数据（12A）灵敏度、（12B）非线性、（12C）对称性和（12D）总误差，请参见图12中的图表。
F级igure 12A. ACS709-20BB Sensitivity versus Ambient Temperature at IP = 37.5 A
图12B:IP=37.5 A时ACS709-20BB非线性与环境温度的关系
F级igure 12C. ACS709-20BB Symmetry versus Ambient Temperature at IP = 37.5 A
图12D:ACS709-20BB总误差与IP=37.5 A时的环境温度
图13中的图表显示了工作环境温度范围内的过电流故障电平误差分布。数据来自数量有限的设备，仅供参考。
F级igure 13. ACS709-20BB Overcurrent Fault Error versus Ambient Temperature
The leadframe 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 ACS709 family devices exhibit a high level of leadframe noise rejection as table 6 reveals. In addition, figure 14 indicates performance as a function of frequency.

表6。典型的电容耦合
20伏p-p公司Signal on the Sensed Current Path

频率
(MHz)

五OUT
(mVp-p公司)

噪声Rejection
（分贝）

5

5

−72

10

16

−62

15

40

−54

20

58

−51
电容耦合
图14。ACS709噪声抑制与噪声频率