Integrated fluxgate sensor provides closed-loop current sensing

June 02, 2015 // By Graham Prophet
With signal conditioning and compensation coil driver in a single package, this device from TI claims high accuracy, dynamic range and linearity, and simplified system design, from a high level of integration.

Texas Instruments says this is the first magnetic sensing integrated circuit with a fully integrated fluxgate sensor and compensation coil driver, along with all the required signal conditioning circuitry. Integration enables the DRV421 to provide best-available sensor accuracy and linearity, high dynamic range, and simplified system design compared to traditional closed-loop sensors. TI says that system designers will be able to more easily develop magnetic closed-loop current sensors for applications such as motor control, renewable energy, battery chargers and power monitoring.

The device allows precise control over motors and automation equipment with an overall sensor accuracy of less than 0.1%. It reduces coupling between the compensation coil and the fluxgate sensor, as well as emissions from fluxgate excitation, to provide high linearity. High dynamic range comes from the built-in closed-loop magnetic core degaussing procedure and offset calibration increase dynamic range up to six decades while supporting higher system-level accuracy, compared to traditional solutions. As the first fluxgate sensor supporting 3.3-V operation, the DRV421 simplifies the interface to integrated ADCs on low-power microcontrollers.

The DRV421 evaluation module ( DRV421EVM) enables designers to evaluate the IC, for $49. Sumida Corporation has introduced the SC2912, a magnetic module that system designers can place on top of the DRV421 as a printed circuit board (PCB) component.This allows engineers to design universal platform solutions targeting a wide range of current levels while choosing the appropriate magnetic module for their specific use case.

“The novel and intuitive approach of our DRV421 complementary module gives customers a new degree of freedom for a closed-loop sensor module,” said Mr. Seiji Shimizu, assistant manager of signal and power solutions for the Automotive and Industry Business Unit, Sumida. “The combination of our module technology and TI’s DRV421 gives customers an unprecedented level of accuracy, linearity, dynamic range, sensitivity and ease of use.”

The DRV421 comes in a 4 x 4-mm quad flat no-lead (QFN) package. Pre-production samples are available now.