Table 5-24 CapTIvate Signal-to-Noise Ratio Characteristicsover operating free-air temperature range from –40°C to 105°C ambient (TA), unless otherwise noted
||TA = 25°C, Ct > 0.5 pF, Cp < 20 pF, >2.5% change in capacitance(2)
|TA = 0°C, Ct > 0.5 pF, Cp < 20 pF, >2.5% change in capacitance(2)
|TA = –40°C, Ct > 0.5 pF, Cp < 20 pF, >2.5% change in capacitance(2)
SNR is defined as the ratio of the measured change in electrode capacitance due to a touch compared with the measured change in capacitance due to the device noise floor. For additional detail on SNR in capacitive sensing applications and how to measure it in your system, see Sensitivity, SNR, and Design Margin in Capacitive Touch Applications
(2) Ct represents the increase or decrease in electrode capacitance due to a touch. Cp represents the inherent parasitic capacitance of the sensing electrode that is present when no touch is applied. Therefore, the touch signal is defined as Ct/Cp, expressed as a percent change in capacitance. Increasing Ct or decreasing Cp increases signal.