Hall Effect Current Sensors and EMI Susceptibility Tests

24/11/2022


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Using Hall effect current sensors, users can obtain accurate, low-cost, and fast current sensing with a small size and high sensitivity. But the output voltage of the sensor can compromise the reliability of the IC and system if the output voltage is too high. This is because the output voltage must not be connected to a voltage greater than the IC's supply voltage.

However, the output voltage of the sensor can be altered to increase its usable range. This is done by widening the slot of the ferrite toroid. The effect of this change is that the core will not only reduce the flux coupling but also increase the effective linear current range. However, this has not yet been fully documented.

EMI susceptibility tests are conducted to understand the effects of conducted EMI on Hall affecting the current sense resistors . In these tests, conducted EMI is radiated from the device and measured using a Bulk Current Injection (BCI) method. In these tests, the radiated EMI is superimposed on the output terminal of the Hall effect current sensor. The magnitude of the induced offset voltage is measured from 500 kHz to 1 GHz. The results show that the induced offset voltage varies with the RF incident power. It is also noted that different signs of induced offset indicate different nonlinear mechanisms. In addition, the results show that the sensitivity of the device is conservative. This implies that users are advised to reconcile precise current sensing limits with the HEDs' specifications.

The results of the radiated EMI susceptibility tests show that the Hall effect current sensor is susceptible to conducted EMI. The output voltage of the sensor is distorted by the electromagnetic field distribution inside the TEM cell. These disturbances are then rejected by 100 nF filter capacitors placed at the main block and Hall sensor leads. The output voltage of the Hall effect current sensor is then processed by the detection block, which includes a hysteresis threshold comparator.

In the BCI experiments, several current sensing circuits were designed and tested. The RF magnetic field is parallel with the Hall sensor surface in Setup A and orthogonal to the device in Setup B. A high-powered RF magnetic field was used to generate an induced offset voltage in the range of 500 kHz to 1 GHz. EMI susceptibility tests were conducted for the same RF incident power, using different PCB surfaces and with the same Hall sensor distance.

In this study, the inclination of the Hall effect current sensor was also examined. The results show that the inclination increases with the same distance and RF incident power. The inclination was studied for the same PCB surface and at the same EMI susceptibility level. To get more on hall effect sensors, visit the hall effect current sense resistor manufacturer here.

As shown in Figure 2, the most significant filter capacitances are the encircle capacitances. In addition, the voltage drop across the R s e n s e is also processed by the detection block. In addition, the detection block contains a non-inverting gain stage. You can get more enlightened on this topic by reading here: Check out this related post to get more enlightened on the topic: https://www.huffpost.com/entry/7-space-technologies-that-changed-the-world_b_5a45682be4b0d86c803c75bd.


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