LDC1000, when inductor Rp is too small, what is the measures.

Shinichi Inoue

Guru 21646 points

Dear Specialists,

My customer is considering lDC1000.

He has a question, could you please advise?

---question---

LDC1000 could sense Rp from 798ohm to 3.93Mohm.

If the inductance Rp is very small, less than Rp min, what is the measures ?

In case of 0.4uH inductance, it should be added external resistance?

Best regards,

Shinichi

over 9 years ago

0 Luke LaPointe over 9 years ago

TI__Genius 13335 points

Hello Shinichi,
We cannot recommend operating the LDC1000 below the minimum Rp value. Adding series resistance decreases Rp further which is not recommended. You need to add more inductance or more capacitance to increase the Rp value into the appropriate range. You can also measure the Rp value in your system with an impedance analyzer or a signal generator with oscilloscope. Please refer to the following application note: www.ti.com/.../snoa936.pdf
Regards,
Luke

0 Shinichi Inoue over 9 years ago in reply to Luke LaPointe

Guru 21646 points

Dear Luke

Thank you for your reply.

I'll feedback the customer low inductance is not recommended.

And I suggest to change the inductance or capacitance.

I appreciate your great help.

Best regards,

Shinichi

0 Luke LaPointe over 9 years ago in reply to Shinichi Inoue

TI__Genius 13335 points

Hello Shinichi-san,

I should also note that increasing the capacitance also decrease Rp which is not recommended. You can add a coil in series to increase the inductance. The downside is that the signal will be diluted by the inductance ratio. You will need to determine if you still have a enough signal with the added inductance.

Regards
Luke

0 Shinichi Inoue over 9 years ago in reply to Luke LaPointe

Guru 21646 points

Dear Luke

Thank you for your reply.

I'll send the customer your additional advise.

I appreciate your great help.

Best regards,

Shinichi

Sensors

Sensors forum

LDC1000, when inductor Rp is too small, what is the measures.