FDC2112: which chip to perform detection using a big size coplanar sensor

Marc Friedheim

Part Number: FDC2112
Other Parts Discussed in Thread: FDC1004, , FDC2212

Hello,

I'm actually needing your advise for product/part number(s).
We're setting up an application with big size conductive sensor to measure small/low profile objects with a coplanar configuration. We think we need a capacitive to voltage detection chip.

We did try the FDC1004 before, but it has a small offset limiting the possibility of large conductors as sensor.

I'm checking the FDC2112 as an option, but perhaps you recommand other options as well?

Question2:
As for the FDC 1004 resp. FDC2112, what kind of excitation signal is outputted? Is it a sine? Square? Please define.

Question3:
As for the FDC2112, it possible to change the input frequency. Should this be a sine or square wave signal?

Thanks

over 1 year ago

0 Justin Beigel over 1 year ago

TI__Genius 17690 points

Hello,

If you are considering the FDC2112, the FDC2212 is a higher resolution version that you can consider.

In regards to question 2, the FDC1004 has a square wave exciter inside the chip that works on the switch-cap architecture. The FDC2112 uses an LC tank on the sensor channel and senses the capacitance based on a resonant architecture. More information on the two approaches can be found here: https://e2e.ti.com/blogs_/b/analogwire/archive/2015/10/20/capacitive-sensing-which-architecture-should-you-choose.

For question 3, the FDC2112 operating frequency is determined by the LC tank on the sensor channel. It will be a sine wave that changes frequency as the capacitance on the sensor changes.

Best Regards,

Justin Beigel

Sensors

Sensors forum

FDC2112: which chip to perform detection using a big size coplanar sensor