Susie Maestre

user Electronics Engineer

city Innovuze Solutions Inc.

  • Open Loop Magnetic Field Sensing Evaluation Module

  • Created: Feb 14, 2016

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A magnetic field sensor is an electromechanical device that is used for detecting and measuring magnetic fields. This device is designed for single-axis magnetic field-sensing applications. It enables electrically isolated, high-sensitivity, and precise DC and AC field measurements. The fluxgate sensors offer significantly higher sensitivity, lower drift, lower noise, and high linearity and enables up to 1000-times better accuracy of the measurement. This device provides an integrated fluxgate sensor (IFG) with an internal compensation coil to support a high-accuracy sensing range of ±2mT with a measurement bandwidth of up to 47kHz. The low offset, offset drift, and noise of the sensor, combined with the precise gain, low gain drift, and very low nonlinearity provided by the internal compensation coil, result in unrivalled magnetic field measurement precision. The output of the DRV425 is an analog signal proportional to the sensed magnetic field.

This reference design is a DRV425EVM Board that is used to evaluate the DRV425 integrated circuit. This device can be powered by a 3.0V-5.5V DC supply. The supply voltage is applied to J1 pin4 (VDD) referenced to pin 3 (GND). It has an internal reference source, which is enabled automatically when the appropriate power source is applied to the device. There are three options for the reference voltage, which depend on the state of two reference selection pins RSEL1 and RSEL0. The resistors R3, R5, and R8 configure as pull-up resistors for RSEL0, RSEL1, and BSEL respectively. The resistors R2 and R9 are 10-kΩ pull-up resistors on the Over Range (/OR) and Error (/ERROR) flag output pins respectively.

The magnetic sensors are used in a broad range of applications such as position, indirect AC and DC current, or torque measurement. On the other hand, hall-effect sensors are most common in magnetic field sensing, but their offset, noise, gain variation, and nonlinearity limit the achievable resolution and accuracy of the system. This particular design is useful in the applications such as linear position sensing, current sensing in busbars, over-the-trace current sensing, and general-purpose magnetic-field sensors.