LDC0851: Output always HIGH, not detecting metal

Part Number: LDC0851

Tool/software:

Hello,

I would like some help to verify if there is any issue with how the LDC0851 circuit is designed. I have uploaded the schematic and gerber files.

We have assembled the board and components. The output is always high (3.3V) even when a metal is directly touching the coil

We placed the Lsense coil on the bottom layer and inner 2 layer (layer just above bottom layer) since we will be mounting the board on a flat surface. 

The LREF coil is on the top layer and inner 1 layer (layer just below the top layer).

I followed the coil design webbench and used a coil generator plugin for Kicad. 

16mm outer diameter, 15 turns, 0.178mm trace width and 0.178mm trace spacing

1oz copper and the resulting inductance should be 9.075uH

Top and Bottom Layer have counter clockwise coil direction

Inner Layers have clockwise coil direction.

 Inductive_Sensor_LDC0851.pdf

LDC0851_GERBER_update.zip

Thanks,

Deniel

  • Hello,

    Just a follow-up

    We have assembled 4 boards. These are all hand soldered.

    Only 1 out of the 4 is working. 

    2 out of the 4 has the output always High at 3.3V

    The other 1 has 0V output.

    aside from looking at the design files that I provided, could the issue be attributed with the hand soldering process?

    Or is there anything in the design that might suggest a marginal failure

    Thanks,

    Deniel