In a proposed product, the inductance of a spring is to be measured. The spring resides in a fuel tank which makes it difficult to site the LDC and the associated LC tank components in close proximity. From reading this forum there appears to be a need to place a fixed inductor (arbitrarily selected as 3.9uH) in series with the spring to raise the minimum inductance from 1.7 uH to 5.5uH, in an attempt to improve the resolution. The maximum inductance would be 6.3uH. This inductor, and the tank capacitor (2200pF for the LDC1000, or 3300pF for the LDC1612) must be placed about 700 mm from the spring, and connected with a twisted pair.
The minimum usable measurement resolution should be 5%. 1% would be better.
1. What problems are likely to arise with this scheme?
2. How can the actual resolution be determined in the design?
The LDC1612 is preferred because of it's ability to use a lower Rp (hence fsensor and higher resolution), and that it only requires a 3.3V supply, the same as the MSP430 that would be talking to it. However, I am unable to find availability details for this part.
3. When will samples be available?
4. When will it be stocked by distributors?
regards, Errol
