8.2.1.2.2 Calculating Sensor Capacitor

Sensor frequency depends on various factors in the application. In this example, use Equation 8 to calculate the sensor frequency to achieve an output data rate of 28 KSPS per the design parameter.

Equation 8.

With an LDC1001 RESPONSE_TIME setting of 384 and an output data rate specification of 28 KSPS, the sensor frequency calculated in Equation 8 is 3.6 MHz.

Using Equation 9, the sensor capacitor is 108 pF with the sensor inductance of 18 µH. A 100-pF sensor capacitor will slightly increase the sensor frequency to 3.75 MHz and provide a sample rate of 29.3 KSPS.

Equation 9.

As the target interacts with the sensor inductance, the apparent inductance will decrease. When the target is at the 1-mm minimum distance for this application, the maximum interaction will occur, and the sensor frequency will increase to 3.95 MHz.