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LDC1101EVM: LDC1101: How does the measurement of the inductance work in detail ?

Johannes Meyer
Prodigy 10 points
Part Number: LDC1101EVM
Other Parts Discussed in Thread: LDC1101

Hello,

In an current prototype project I work with the ldc1101. I have to make some specifications about the measurement precision and the error propagation of the Sensor. For those specs I need a detailed description how a inaccuracy of the coil or the capacitance will propagate through the system.

  • 0
    TI__Genius 13650 points
    Hello Johannes,
    to measure the inductance, the LDC1101 compares the oscillation frequency of the sensor (sensor coil + sensor capacitor + sensor parasitics) to the reference clock. The time window of sensor oscillation cycles over which LDC1101 counts is set by the LHR_RCOUNT register.
    Equations 11 and 12 in the datasheet can be combined to calculate exactly how much of an effect (in codes) any undesired shift in oscillation frequency (eg. temperature drift of the sensor capacitor) or change in reference clock frequency (eg. clock jitter) has.