What capacitance range can KE17Z support

[linxianti]

Hello team

    If there any specification of supported capacitance range for KE17Z, using mutual-capacitance mode.

    And is it possible for application software to get the capacitance value for KE17Z? For example, if there is register indicate the acquired result for capacitance sensor.

Best Regards.

Xianti 

[linxianti]

Hello Celeste

    Thanks for your reply.

    Actually we have a preliminary capacitance sensor design, the measured capacitance value is more than 200 pF. 

    I think we measured it via mutual-capacitance mode.

    And we are searching more cost-competitive solution. 
    So do you mean the capacitance range depend on the sensor design, and KE17Z can measure all the capacitance changing of the sensor?

Thanks. & Regards.

Xianti LIN

[Celeste_Liu]

Hello @linxianti ,

Yes, on KE17Z the measurable range isn’t a fixed spec. It depends on your sensor design (electrode geometry, overlay/dielectric, PCB routing). The TSI adapts via tuning (function clock, charge/discharge timing, reference counts, sensitivity boost, shielding).

KE17Z can detect capacitance changes over a wide range if the TSI parameters are tuned to avoid saturation (too large node capacitance) or noise floor (too small coupling). For mutual mode, the TX–RX coupling is typically a few–tens of pF, a measured >200 pF is usually the node-to-ground parasitic, which may require slower scan (lower clock, longer timing) to keep counts in range.

BR

Celeste

[linxianti]

Hello Celeste

    So for a capacitance signal which is more than 200 pF, it may be measured via self-capacitance mode. Is my understanding right?

BR.

Xianti

[Celeste_Liu]

Hello @linxianti ,

No. A sensor node having more than 200 pF does not necessarily mean it must be measured by self‑capacitance mode. Mutual‑cap mode can still be used if parameters are adjusted properly.

BR

Celeste

[Celeste_Liu · Accepted solution]

Hello @linxianti ,

Thanks for your post. Please refer to KE17Z Dual Touch Sensing Interface (TSI) User Guide.

We only provide typical design reference value and there is no officially defined minimum or maximum supported capacitance.
The actual supported range depends on electrode pattern design, thickness/dielectric of
overlay and PCB routing.

Celeste_Liu_0-1768206699878.png

Application software can read the raw mutual-cap sensing result from TSIx_DATA[TSICNT], but this value is not a direct capacitance (pF) reading.

Celeste_Liu_1-1768207072467.png

Celeste_Liu_2-1768207894408.png

Please refer to section "3.3 Mutual-cap sensing mode" for more details.

BR

Celeste

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