LDC2112: Ferrite sheet

Alex Wu2

Intellectual 260 points

Part Number: LDC2112

Hi Kristin

If LED is placed on the surface of the LED FPC and the target metal is paste behind. ITB FPC is a coil

I refer to the specification sona957a, and put ferrite on the back of ITB FPC.

There is no hole in the target metal. Will the target inductance be reduced? Are there any risks with this design?

Thank you

URL:e2e.ti.com/.../inductive-sensing-how-to-shield-from-metal-interference

over 4 years ago

0 Kristin Jones93 over 4 years ago

TI__Genius 17440 points

Hi Alex,

This looks like a better solution than the options you previously shared with cutouts in the target metal. I have two comments:

1. What is the gray layer in between the ITB FPC and the ferrite? In this stack-up, the metal FPC stiffener would act as the target for the sensor coil on the ITB FPC. If there is another layer of metal directly below the ITB FPC, then the sensor coil will likely not be able to detect the metal FPC stiffener. The ferrite needs to be positioned in between the sensor coil and the interfering metal in order to be effective.

2. The LEDs may impact the mechanical response of the button, but I've not seen this type of design before so I can't advise what kind of problems could occur. It may not cause any problems, or it may cause significant problems.

Best Regards,