Determine which version of the TPS3704-Q1 best fits the monitored rail (V_MON) and window tolerances found on Table 9-3. The TPS3704-Q1 allows overvoltage and undervoltage monitoring for precise voltage supervision of common rails between 0.4 V and 5.5 V. This application calls for very tight monitoring of the rail with only ±5% of variation allowed on the 1.2-V_CORE rail. To make sure this requirement is met, the TPS37042-Q1 was chosen for its ±3% thresholds. The 3.3-V_I/O is more flexible and can operate up to 8% variance. Because the TPS3704-Q1 comes in various tolerance options, the ±6% thresholds can be chosen for this voltage rail. To calculate the worst case for V_IT+(OV) and V_IT-(UV), the accuracy must also be taken into account. The worst-case for V_IT+(OV) and V_IT-(UV) can be calculated shown in Equation 5 and Equation 6 respectively:

Hysteresis must also be taken into account when determining the OV and UV thresholds such that the release point after the fault is higher than the power-supply tolerance limits. See Figure 6-1 for more details.

When the outputs switch to a high impedance state, the rise time of the RESETx/RESETx pin depends on the pullup resistance and the capacitance on that node. Choose pullup resistors that satisfy both the downstream timing requirements and the sink current required to have a V_OL low enough for the application; 10-kΩ to 1-MΩ resistors are a good choice for low-capacitive loads.