The LDC0851 is an inductance comparator with push/pull output. It utilizes a sensing coil and a reference coil to determine the relative inductance in a system. The push/pull output (OUT) switches low when the sense inductance drops below the reference and returns high when the reference inductance is higher than the sense inductance. Matching the sense and reference coils is important to maintain a consistent switching distance over temperature and to compensate for other environmental factors. The LDC0851 features internal hysteresis to prevent false switching due to noise or mechanical vibration at the switching threshold. The switching threshold is set by the sensor characteristics and proximity to conductive objects, which is considered Basic Operation Mode described further in section Basic Operation Mode. The LDC0851 also features a Threshold Adjust Mode where an offset is subtracted from the reference inductance to change the effective switching point as described in section Threshold Adjust Mode.

The sensing coil is connected across the LSENSE and LCOM pins and the reference coil is connected across the LREF and LCOM pins. A sensor capacitor is connected from LCOM to GND to set the sensor oscillation frequency. The sensor capacitor is common to both LSENSE and LREF making the inductance measurement differential.