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Response time vs. Proximity data noise

Minkyun Noh
Prodigy 170 points

Hello,

I am wondering the relation between the response time value (0x04[2:0]) and the proximity data noise. What I have observed is that the longer response time the lower noise level. Does LDC1000 has a low pass filter whose cutoff frequency is a function of the response time (0x04[2:0]) setting? Thanks!

Best regards,

Minkyun 

  • 0
    TI__Genius 13650 points

    Hello Minkyun,
    The response time represents the number of sensor oscillation cycles used to measure the sensor frequency. A longer response time allows the LDC more time to take a measurement, which results in a lower noise floor.
    Response time is a trade-off between noise level and sampling rate.

  • 0 in reply to Ben Kasemsadeh
    Prodigy 170 points

    Thanks!
    One more question; I also observed that the longer response time helps reduce the noise level even if I don't provide an external clock. Does LDC1000 has an internal clock built in? Then what's the clock frequency?

    Best regards,
    Minkyun

  • 0 in reply to Minkyun Noh
    TI__Genius 13650 points
    Hi Minkyun
    Apologies for the confusion. There was a typo in my previous response; it should have read "The response time represents the number of *sensor oscillation cycles* used to measure the sensor frequency."
    This is also the reason why you see improved noise floor without reference clock.