• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 31 subscribers
  • Views 301 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LDC1612: Sensor frequency expression

Matthias Meier1
Prodigy 180 points
Part Number: LDC1612

Dear TI Experts,

Would it be possible to share how you arrived at the expression for f_SENSOR shown in the LDC1612/1614 datasheet, section 8.1.2?  I'm curious because it differs from the solution for the resonant frequency of a lossy, parallel LCR-tank.

Thanks!

  • 0
    TI__Expert 6625 points
    Hi Matthias,
    You need to solve the resonant frequency of the LC tank. Here is a link that goes over the derivation is much detial: physics.info/.../.

    Best Regards,
    Bala Ravi
  • 0 in reply to Bala Ravi
    Prodigy 180 points

    Hi Bala,

    Your link points to the derivation of the expression for calculating the resonance frequency of an ideal LC-tank, which is NOT what I was asking about. Perhaps I should clarify...

    1. My question is NOT in regards to the simplified resonance equation for an ideal LC-tank which assumes a pure (non-lossy) inductor, i.e. f0 = 1/(2*pi*sqrt(L*C)).  The derivation of this equation is clear to me.

    2. My question is also NOT in regards to the resonance equation for an LCR-tank which assumes an impure (lossy) inductor, i.e. f0 = 1/(2*pi) * sqrt(1/(L*C) - (R/L)^2).  The derivation of this equation is also clear to me.

    3. What I'm actually asking is, how did you arrive at equation (1) in the datasheet, section 8.1.2 on pg. 35, i.e. f_SENSOR = 1/(2*pi*sqrt(L*C)) * sqrt(1 - 1/Q^2 - 5e-9/(Q*sqrt(L*C)))?

    Thanks,

    Matthias

  • 0 in reply to Matthias Meier1
    TI__Mastermind 23810 points
    Matthias,

    Unfortunately, we cannot help with that derivation. The point is that it simplifies to f_sensor=1/(2*pi*sqrt(L*C).