The SENSE input can vary from 0V to 6.0V, regardless of the device supply voltage used. The SENSE pin is used to monitor a critical voltage rail or push-button input. If the voltage on this pin drops below V_IT-, then RESET/RESET is asserted after the sense delay time set by CTS. When the voltage on the SENSE pin rises above the positive threshold voltage V_IT- + V_HYS, RESET/RESET deasserts after the reset delay time set by CTR. The internal comparator has built-in hysteresis to make sure well-defined RESET/RESET assertions and deassertions even when there are small changes on the voltage rail being monitored.

The TPS3899 device is relatively immune to short transients on the SENSE pin. Glitch immunity (t_{GI_VIT-SENSE}), found in Section 5.6, is dependent on threshold overdrive, as illustrated in Figure 5-7. Although not required in most cases, for noisy applications, good analog design practice is to place a 10nF to 100nF bypass capacitor at the SENSE input to reduce sensitivity to transient voltages on the monitored signal.