SNVSB66A July 2018 – October 2021 TPS3431
The CWD pin provides the user the functionality of both high-precision, factory-programmed watchdog timing options and user-programmable watchdog timing. The TPS3431 features three options for setting the watchdog timer: connecting a capacitor to the CWD pin, connecting a pull-up resistor to VDD, and leaving the CWD pin unconnected. The configuration of the CWD pin is evaluated by the device every time VDD rises above VDD (min). The pin evaluation is controlled by an internal state machine that determines which option is connected to the CWD pin. The sequence of events typically takes 381 μs (tINIT) to determine if the CWD pin is left unconnected, pulled-up through a resistor, or connected to a capacitor. If the CWD pin is being pulled up to VDD, a 10-kΩ resistor is required.