DRV425 Datasheet, PDF (18/37 Pages) Texas Instruments – DRV425 Fluxgate Magnetic-Field Sensor

DRV425
SBOS729 – OCTOBER 2015
www.ti.com
7.3 Feature Description
7.3.1 Fluxgate Sensor Front-End
The following sections describe the functional blocks and features of the integrated fluxgate sensor front-end.
7.3.1.1 Fluxgate Sensor
The fluxgate sensor of the DRV425 is uniquely suited for high-performance magnetic-field sensors because of
the high sensitivity, low noise, and low offset of the sensor. The fluxgate principle relies on repeatedly driving the
sensor in and out of saturation; therefore, the sensor is free of any significant magnetic hysteresis. The feedback
loop accurately drives a compensation current through the integrated compensation coil and drives the magnetic
field at the sensor back to zero. This approach supports excellent gain stability and high linearity of the
measurement.
The DRV425 package is free of any ferromagnetic materials in order to prevent magnetization by external fields
and to obtain accurate and hysteresis-free operation. Select non-magnetizable materials for the printed circuit
board (PCB) and passive components in the direct vicinity of the DRV425; see the Layout Guidelines section for
more details.
The orientation and the sensitivity axis of the fluxgate sensor is indicated by a dashed line on the top of the
package, as shown in Figure 61. Figure 61 also shows the location of the sensor inside the package.
Sensitivity Axis Indication
(Top View)
Sensor Location
(Top View)
Sensor Location
(Side View)
>
DRV425
TI Date
Code
Top
Bottom
0.4 mm ± 0.025 mm
Figure 61. Magnetic Sensitivity Direction of the Integrated Fluxgate Sensor
The sensitivity of the fluxgate sensor is a vector function of its sensitivity axis and the magnetic field orientation.
Figure 62 shows the output of the DRV425 in dependency of the orientation of the device to a constant magnetic
field.
2.65
2.6
2.55
2.5
2.45
2.4
2.35
0
30 60 90 120 150 180 210 240 270 300 330 360
Angle (G)
D063
Figure 62. DRV425 Output vs Magnetic Field Orientation
18
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