coil design for LDC 1614

Santosh Banisetty

Intellectual 440 points

Hello,

I am planning to design a prototype coil to evaluate LDC 1614. The requirements are as follows:

sensor frequency: 500 kHz

sensing distance: 1 inch

outer diameter of coil: 2 inch

inner diameter of coil: 2/3 inch

2 layer pcb 6 x 6 mils (trace and spacing)

capacitor : ?

number of turns: ?

and how can i design a footprint of a circular coil? does orcad have any tool to design one?

I appreciate if someone can suggest me cap value, number of turns, tool to design and any other parameter (if I forgot). I planning to design two or three different coils to evaluate performance. so, help me decide 3 different coil designs so that the distance vs inductance is as linear as possible.

over 10 years ago

0 Chris Oberhauser66 over 10 years ago

TI__Genius 14270 points

Hello Santosh,

I believe you already have the LDC tools spreadsheet. From the main page of the spreadsheet, select the "Spiral Inductor Designer".

Then on the table fill out your settings you already know - the outer diameter is 2inches, the number of layers is 2, the trace and space are 6mil/6mil. Then adjust the number of turns until you have the desired inner diameter (you won't get exactly 0.6667inches, but probably more like 0.656inches). Make sure you set the PCB thickness (a common thickness is 63mils).

Once you have set the geometries, you will have your inductance. Then go back to the main page, and use the quick calculator to find the capacitance that provides the desired sensor frequency.

Unfortunately, we do not have Orcad tools; although we can provide Altium scripts to design a sensor.

Regards,

ChrisO

0 Santosh Banisetty over 10 years ago in reply to Chris Oberhauser66

Intellectual 440 points

Thank you Chris,

Review my design below. Are all the numbers good? Do I need to worry about Q factor?

0 Natallia Holubeva1 over 10 years ago in reply to Santosh Banisetty

TI__Expert 6550 points

Hello Santosh,

The quality factor od 24 is very resonable. Other numbers look OK as well.

Best Regards,
Natallia Holubeva

0 Santosh Banisetty over 10 years ago in reply to Natallia Holubeva1

Intellectual 440 points

Will try with the above specifications.

Thank you

0 Natallia Holubeva1 over 10 years ago in reply to Santosh Banisetty

TI__Expert 6550 points

Snatosh,

Please let us know if there are any other questions.

Best Regards,
Natallia Holubeva

0 Chris Oberhauser66 over 10 years ago in reply to Santosh Banisetty

TI__Genius 14270 points

Hi Santosh,

Please take a look at webench.ti.com/wb5/LDC for a useful tool when designing custom coils.
Regards,
ChrisO

0 Santosh Banisetty over 10 years ago in reply to Chris Oberhauser66

Intellectual 440 points

Hello Chris,

Thank you, that is really a good tool. It certainly helps, But it does not have any graphs related to inductance vs distance. It would be nice if we can see the simulated response.

0 Chris Oberhauser66 over 10 years ago in reply to Santosh Banisetty

TI__Genius 14270 points

Thank you for the feedback. We are constantly improving the LDC support tools, and I will see if I can incorporate it.

Regards,

ChrisO

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coil design for LDC 1614