Electronic – Question Regarding Capacitive Sensor IC

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I have this Capacitive Sensor IC

I am trying to understand and analyze how to use this IC.

In the datasheet, on page 13 – Function description, it is mentioned as "There are four selectable non-harmonic sensor frequencies for generating the sensor driver output
signal: 45.45 kHz, 71.43 kHz, 100 kHz and 125 kHz. This can be set in FREQ register (see 7.2.7)"

I am not able to understand the purpose of this frequency in the IC? For what purpose is the frequency?

Like, is this the frequency for the IC internal working derived from the CLK input from the Host or does this frequency available on any other pin of the which (like, can this frequency be measured external to the IC?)

My questions :

  1. What does the frequency setting serve as? What is its purpose? From which section in the block diagram is this frequency generated from?

  2. I couldn't find the "Sensor driver output" block on the block diagram? What is the sensor driver output and what does it do?

Best Answer

What does the frequency setting serve as? What is its purpose? From which section in the block diagram is this frequency generated from?

Capacitive sensors work by sending a waveform (in this case a sine wave) through a capacitor (might be air) and then sensing the change in voltage, and calculating a change in impedance. The frequency setting changes the frequency of the sine wave that the TX DAC outputs.

I couldn't find the "Sensor driver output" block on the block diagram? What is the sensor driver output and what does it do?

The sensor driver output is the 10 pins SEN[0:9] (sen 0 through 9) and this is what the impedance of what the chip is trying to measure is attached to. enter image description here Source: https://www.mouser.in/datasheet/2/588/AMS_AS8579_Datasheet_V2_00-1853724.pdf