Texas Instruments have announced what is thought to be first inductance to digital converter chip. The principle use of the device is to measure (with sub-Micron precision) the movement or displacement of a conductive target. The LDC1000 excites a sensing coil (which can be conveniently printed on the PCB) and measures its coupling to a conductive target, the nearer the target the greater the coupling.


As well as measuring axial displacement, a tapered target pattern can move, at a fixed spacing, past the coil to give linear movement measurement. As the taper pattern passing the coil widens, coupling increases. A shallower taper allows the measurement of greater displacement. The tapered target concept can be shaped onto a circle to measure angular shaft displacement.


Measurement is non-contact so there are no issues of wear and tear on the sensing element and it is unaffected by the presence of dust, dirt, oil and moisture. The LDC1000 typically hooks up to a microcontroller using its standard slave SPI interface. It can be programmed to continually supply measurement data or to generate an interrupt or wake-up whenever measured values exceed programmed thresholds.