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LDC1612: Which is best solution? (and other questions.)

ACGUY
Guru 11170 points
Part Number: LDC1612
Other Parts Discussed in Thread: LDC1101, LDC1101EVM, LDC1312EVM

Hello E2E,

I catched up new customer that designing the sensor coil product.
Please your advice for them.

Target : carbon steel, W=50mm / H=50mm / d=4mm.
Sensor coil size : D=7mm(max).
Measuring distance : 1mm(max).
Resolution : 1um(max).

Q1 : LDC16xx, LDC13xx or LDC1101, which is your recommended device?
Q2 : I tried Webench. Why does not elected LDC1101?

They bought and tested LDC1000-EVM already.
When the distance between A and B is too close, EVM outputs data are all "0" or all "1".

Q3 : Is it cause because saturation for resonance frequency?

Distance from target to coil, 1mm -> 100um -> 1mm -> 100um, repetition...

The data sampled by them differ slightly for each sampling.
Q4 : Why data different?

Regards,
ACGUY

  • 0
    TI__Genius 13335 points

    Hello,

    Allow me to address your questions below:

    ACGUY said:
    Q1 : LDC16xx, LDC13xx or LDC1101, which is your recommended device?

    Depending on the speed, accuracy, voltage supply, interface, and other requirements the device recommendation will vary. Please review the following application note for more information:

    LDC Device Selection Guide [SNOA954]: www.ti.com/.../SNOA954

    ACGUY said:
    Q2 : I tried Webench. Why does not elected LDC1101?

    The Webench tool has not been updated to include the LDC1101, however the coil design will be similar regardless of the device. There is currently no plan to update the Webench tool.

    ACGUY said:
    They bought and tested LDC1000-EVM already.
    When the distance between A and B is too close, EVM outputs data are all "0" or all "1".

    Q3 : Is it cause because saturation for resonance frequency?

    It is not clear whether this is referring to the comparator output of the LDC1000 or the Proximity data. It's likely that the RP_MIN and RP_MAX values are not set properly, or that there are some other settings in the device not configured correctly. If using the LDC1000, please refer to the datasheet for specific guidance on its use. 

    ACGUY said:
    Distance from target to coil, 1mm -> 100um -> 1mm -> 100um, repetition...

    The data sampled by them differ slightly for each sampling. 

    Q4 : Why data different?

    I would recommend testing the same experiment with either a LDC1101EVM, LDC1312EVM, or LDC612EVM which have improved measurement repeatability and accuracy.

    Regards,

    Luke