LDC1000 working principle and circuit schematic diagram

For existing sensing technologies, whether it is a high-end sensitivity, high-precision ultrasonic sensor, or a low-end, low-cost switching sensor, the LDC1000 can handle these tasks.

How LDC1000 works

The detection principle of LDC1000 inductor is based on the principle of electromagnetic induction. Adding an alternating current to the coil will generate an alternating magnetic field around the coil. At this time, if a metal object (as shown in Figure 3-1) enters this magnetic field, eddy currents will be generated on the surface of the metal object. Eddy currents run in the opposite direction to the coil current. The induced electromagnetic field generated by the eddy current is in the opposite direction to the electromagnetic field of the coil. Eddy currents are related to parameters such as the magnetic permeability and electrical conductivity of the metal body, the geometric shape and size of the coil, and the distance from the head coil to the surface of the metal conductor.

The reverse magnetic field generated by the eddy current couples with the coil, as if there is another secondary coil. In this way, the coil of LDC1000 acts as a secondary coil to form a transformer. As shown in Figure 3-2, due to the mutual inductance of the transformer, the parameters of the secondary coil can be detected on the side of the primary coil.

Let Ls be the inductance value of the primary coil and Rs be the parasitic resistance of the primary coil. L(d) is the mutual inductance, R(d) is the parasitic resistance of the mutual inductance resistance, where d is a function of distance.

If alternating current is only applied to the inductor (primary coil), it will generate an alternating magnetic field and consume a lot of energy. At this time, a capacitor is connected in parallel to the inductor. Due to the parallel resonance of LC, the energy loss is greatly reduced and will only be lost on Rs and R(d). It can be seen that detecting the loss of R(d) can indirectly detect d.

It can be seen from the above that LCD1000 does not directly detect series resistance, but detects equivalent parallel resistance.

Key performance advantages of LDC1000:

Another type of sensor in the industry, the inductive sensor is also widely used in the industrial field. The inductive sensor has a series of advantages such as simple structure, reliable operation, high measurement accuracy, stable zero point, and large output power. Its main disadvantages are sensitivity, linearity and The measurement ranges are mutually restricted. However, the sensor itself has low frequency response and is not suitable for fast dynamic measurements. However, this is not the most fatal shortcoming of inductive sensors, but that it must go through a conversion circuit before it can output electricity. Therefore, for most engineers, the difficult-to-adjust conversion circuit is a stumbling block that hinders the popularization of inductive sensors. The inductance-to-digital converter launched by TI does not require a complex conversion circuit, and the LDC1000 directly outputs a detectable digital signal.

• Higher resolution: Sub-micron resolution can be achieved in position sensing applications through 16-bit resonant impedance and 24-bit inductance values;

• Higher reliability: Provides non-contact sensing technology to avoid the influence of non-conductive pollutants such as oil and dust, which can extend the service life of equipment;

• Higher flexibility: allows sensors to be placed away from electronic products and in locations where PCBs cannot be placed;

• Lower system cost: uses low-cost sensors and conductive targets, no magnets required;

• Endless Possibilities: Supports compressed metal foil or conductive ink targets, opening up endless possibilities for creative and innovative system designs;

• Lower system power consumption: less than 8.5mW in standard operation and less than 1.25mW in standby mode.

"Inductance-to-digital converter is a new way of sensing current operating position and motion. It can provide better performance, higher reliability, higher flexibility, low cost and low power consumption. Very low," Baldwin said.

Specific applications include detecting the speed and position of all magnetic objects, gear position, rotation speed, angle, etc. Target applications include industrial, automotive, consumer, medical, computing and mobile devices, and communications fields. Applications range from simple buttons, knobs and switches to high-resolution heart rate monitors, turbine flow meters and high-speed motor/gear controllers.

Packaging and availability

The LDC1000 is available now in a 16-pin, 4 mm × 5 mm SON package and can be ordered immediately. Automotive-quality versions will be available in the first half of 2014.