The TPS3851 features undervoltage detection for common rails between 1.8 V and 5 V. The voltage is monitored on the input rail of the device. If V_DD drops below V_ITN, then RESET is asserted (driven low). When V_DD is above V_ITN + V_HYST, RESET deasserts after t_RST, as shown in Figure 7-1. The internal comparator has built-in hysteresis that provides some noise immunity and ensures stable operation. Although not required in most cases, for noisy applications, good analog design practice is to place a 1-nF to 100-nF bypass capacitor close to the VDD pin to reduce sensitivity to transient voltages on the monitored signal.

Figure 7-1 Undervoltage Detection