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LDC1001: LDC1001: What is the use of the LDC amplitude setting?

Part Number: LDC1001

Hello TI, as in the question, what is the use of the amplitude and amplitude settings in the LDC settings (1V/2V/4V)?

1. I tried Rp stability (sample data for a long time)

2. Influence of temperature drift during cold start

3. The stability of sensor Rp in high and low temperature environment (-40℃ or +80℃).

The above experiments were all tried and found no advantage or improvement. Does this setting matter? There is no explanation in the pdf, but 4V debugging is recommended.

  • Daohai,

    The different amplitude settings help make the device operation & behavior more robust over different configurations and conditions.

    These devices are basically specialized data converters.
    Instead of quantizing voltage levels, they count axis crossings of the LC oscillator signal (FCOUNT) and compare it to the count of a reference clock (RESPONSE_TIME).
    And just like the traditional A/D converters, signal-to-noise ratio (SNR) matters.

    In low loss designs with low noise, a minimum amplitude may result in the SNR that gives the desired performance.
    For a lossy design and/or a higher noise environment a higher amplitude may be needed to give the SNR and the desired performance. 

    You may be able to use a lower amplitude if your target is close to your sensor, or if you don't need to detect very small target movements.
    In contrast, you may need a higher amplitude if you  need a lot of sensitivity, like when you are trying to detect a very small movement of a target, or you are trying to detect a target that is further away than half of the diameter of the sensor.

    The conditions mentioned depend on the system requirements, the sensor design, and the surrounding environments, 
    Our Excel-based Inductive Sensing Design Calculator Tool can help with some of these concerns, although it does not directly address SNR.