LDC3114-Q1: EMC and ESD protection

Hello Johannes,

Thanks for posting to the Sensing forum! We do have a document that covers some guidelines, the document does not cover LDC3114 but the same ideas can be applied. You can read this document by following this link: https://www.ti.com/lit/an/snoa962/snoa962.pdf

If the external inductor is not on the same PCB it is less likely for it to have an effect on the device but if they are sharing power lines then might be possible the other board could couple EM noise through these lines.

As far as any ESD, there device already provides some internal ESD protection: 

I am not sure if this is enough protection for your application or if you require more. There are external ESD protection ICs that can be added for further protection, but the ESD protection that comes built in on the devices this is typically enough protection to protect from damage during the manufacturing process. Unless if you think your device will be susceptible to more ESD then it might be necessary to include additional circuitry to protect against these scenarios such as exposing the circuit and being touched by people.

As far the DC path to the inductor are you referring to the inductor on the other board or the sensor coil?

Best,

Isaac

Dear Isaac,

thank you for your fast answer, the explanations and the link to the document.

To your question about the DC path: If we place the inductor on another PCB than the LDC3114, do we need a DC path from the IC-PCB, through the cable to the inductor-PCB, through the inductor and then back through the cable to the IC-PCB? Usually, due to ESD reasons, we use a combination of a series capacitor to block the DC and a varactor to prevent spikes. If we need a DC path through the inductor, as it is in the evaluation board, we have to leave out the series capacitor on the IC-PCB.

Thank you!

Regards,
Johannes

Hello Johannes,

Our LDC experts are out today but should be back on Monday.  I will send this question to them when they return.

Regards,

Mekre

Hello Justin,

thank you for this illustration and the link to the document. The shielding is required for EMI protection, not ESD.

In case of ESD pulses, what kind of protection is possible? +/-2 kV as written in the datasheet of the LDC3114 is not enough for our customer, +/-5 kV is required. Therefore, we need an additional ESD protection. My question was: Is it possible to include a series capacitor in between the external inductor and the LDC3114? Thank you!

Regards,
Johannes