Reference design for a distance and weight measurements system using inductive sensing to incorporate weight and distance measurements into mechanical systems.
Distance and weight measurements are crucial in various industrial and end-equipment systems, where precise and accurate measurements are required for optimal performance. Texas Instruments (TI) has introduced a reference design for distance and weight measurements using inductive sensing to reduce system costs. The reference design is a sub-system design that converts distance measurements into weight measurements using springs with well-known characteristics. The system is designed for building automation and weight scale applications. This design provides a cost-effective solution for incorporating weight and distance measurements into mechanical systems without expensive magnets or other sensing materials. The design suits various applications such as building automation, elevator systems, weight sensors, and load sensors.
The reference design is based on the ultra-low-power microcontroller unit (MCU) MSP430F5232, chosen based on memory, processor power and peripheral module requirements. The design includes the LDC1041, an Inductance-to-Digital Converter that can simultaneously measure both the impedance and resonant frequency of an LC (inductor-capacitor) resonator. It achieves this by maintaining the oscillation amplitude at a constant level through a closed-loop configuration while monitoring the energy dissipated by the resonator. In the reference design, achieving the desired distance measurement performance depends critically on the design of the sensor coil used with the LDC1041. To generate the appropriate sensor coil, based on the sub-system mechanical characteristics, the WEBENCH Inductive Sensing Designer was used. For temperature calibration and power management in the design, the TMP103 digital temperature sensor and the TPS7A4101 low-dropout (LDO) regulator devices are used. To safeguard the JTAG programming interface, the design incorporates the TPD1E10B06 Single-Channel Electrostatic Discharge (ESD) Protection Device.
The distance and weight measurement system can measure distance and weight without using expensive rare-earth magnets or materials. The reference design features calibrated sensor output from the microcontroller and low power consumption of 37.8mW. The design operates at a power supply range of 7Vdc to 40Vdc. The system’s operating temperature ranges from –40°C to 125°C. The inductance-to-digital converter incorporated in the design provides system designers with a cost-effective way to achieve high performance and reliability by using a coil or spring as a sensor. The reference design employs a compact mechanical arrangement to transform linear distance into weight, and the desired information is the weight applied to the mechanical setup.
This reference design has been tested by TI. It comes with BOM, schematics, Gerber file, Printed circuit board (PCB) layout, computer-aided design/ computer-aided engineering (CAD/CAE) symbols, Assembly drawing, Schematic, etc. You can find additional data about the reference design on the company’s website. To read more about this reference design, click here.
