• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 2 answers
  • Subscribers 30 subscribers
  • Views 542 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: Coil Value changes with respect to temperature changes.

Dinesh Kumar2
Prodigy 120 points
Part Number: LDC1612

Need more info on temperature compensation in LDC1612. We are using the same design as in the data sheet.

8.2.6 Application Curves

Common Test Conditions (unless specified otherwise):

• Sensor inductor: 2 layer, 32 turns/layer, 14mm diameter, PCB inductor with L=19.4 μH, RP=5.7 kΩ at 2 MHz

• Sensor capacitor: 330 pF 1% COG/NP0

• Target: Aluminum, 1.5 mm thickness

• Channel = Channel 0 (continuous mode)

• ƒCLKIN = 40 MHz, FIN_DIVIDERx = 0x01, FREF_DIVIDERx = 0x001

• RCOUNT0 = 0xFFFF, SETTLECOUNT0 = 0x0100

• RP_OVERRIDE = 1, AUTO_AMP_DIS = 1, DRIVE_CURRENT0 = 0x9800

  • 0
    TI__Mastermind 23810 points
    Dinesh,

    There is no active temperature compensation on the LDC1612. The easiest way to accomplish compensation is to connect one channel to a reference coil with a stationary target. Both the reference and sense coils will experience the same environmental shifts, so the effects of temperature can be calculated out.

    As a rough rule of thumb, the effect of temperature on the inductance of PCB coils (with C0G capacitors) is about 30ppm/C.

    The oscillator can also drift with temperature, which impacts the measurement (note that this would also be compensated for if a reference coil was used). The internal oscillator has a temperature coefficient of -13ppm/C; however, an external oscillator can significantly lower the noise floor. If using an external oscillator, make sure that the temperature coefficient is low.
  • 0 in reply to Clancy Soehren
    Prodigy 120 points
    Thanks a lot for your response Clancy.
    We are using both the coils for target sensing purpose as our application requires such design.
    So to conclude is this the only reason for the coil value drift wrt temperature ?
  • 0 in reply to Dinesh Kumar2
    TI__Mastermind 23810 points
    It is important to use C0G capacitors with the coils as these have low temperature drift. Other types of capacitors can have significant temperature drift.