The TLV493D-A1B6, a new magnetic sensor from Infineon Technologies, offers accurate three-dimensional sensing with extremely low power consumption in a small 6-pin package.
With its magnetic field detection in x, y, and z axes, the sensor reliably measures linear and rotational movements for applications such as joysticks, control elements (white goods, multifunction knobs) or electric meters (anti tampering).
While conventional linear Hall sensors, Hall switches and angle sensors only detect magnetic field components which are oriented perpendicular to the surface of the chip (GMR angle sensors detect only the planar oriented field component), the TLV493D-A1B6 enables the simultaneous detection of x, y and z coordinates. This three dimensional sensing is possible by integrating both vertical and horizontal Hall plates on the sensor chip. Vertical Hall plates are sensitive to the planar oriented field components in the x and y planes, while the horizontal plate is sensitive to the perpendicular oriented field component (z plane).
The sensor provides a digital output via 2-wire standard I²C interface, which enables bidirectional communication between it and a microcontroller. The sensing unit also contains a temperature sensor. For 3D magnetic sensing the TLV493D-A1B6 provides 12-bit data resolution for each measurement direction. This allows a high data resolution of 0,098 mT per bit (LSB).
Linear magnetic field (B) measurements of the Bx, By and Bz components are possible for the wide linear field range of ±150 mT, supporting measurement over a long magnet movement. The large operation scale also makes the magnet circuit design easy, robust and flexible.
Targeting industrial and consumer applications, the TLV493D-A1B6 can be operated on supply voltages between 2,3 V and 3,5 V and in a temperature range from -40°C to +125°C. Five different power modes pave the way for low current consumption – power down mode consumes just 7 nA while maximum operation peaks at 3,7 mA.
Application: tampering protection of e-meters
Traditional electricity meters have no ability to detect or deal with tampering because they only measure energy based on the voltage and current flowing between the in and out terminals. In such meters, tampering has become very easy and detection difficult. However, electronic meters deployed today have the capability to detect tampering and take appropriate action.
Magnetic interference is probably the most common and easiest way to tamper with a meter. Magnetic current sensors such as a current transformer (CT) are most susceptible to this interference. A powerful permanent magnet, when placed on the case close to the CT, produces a strong magnetic field that quickly saturates the core, thereby rendering the current sensor useless. In the event of the CT being useless, the current reading would be zero and would also make the energy reading zero.
The conventional approach to implement the magnetic sensing for tampering protection is based on two Hall sensors (one soldered on the related PCB and another one vertical to it on a separate small PCB – see Figure 1. This approach comes with some disadvantages like difficult mechanical construction, calibration and tuning. In addition, power consumption and costs are high.
With Infineon’s new 3D sensor there is no extra PCB necessary and system complexity is reduced, which leads to higher reliability. In addition, the TLV493D-A1B6 fulfils all the other demands for this kind of application like large field range, high resolution, temperature measurement, very low power consumption, digital output, no additional components, small package and low costs.
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