ZHCSKK3B December 2019 – February 2022 TPS6594-Q1
PRODUCTION DATA
The watchdog in the TPS6594-Q1 device has a Watchdog Disable function to prevent an unwanted MCU reset in case the MCU is un-programmed or needs to be reprogrammed. In order to activate this Watchdog Disable function for an un-programmed MCU, DISABLE_WDOG pin must be asserted to a logic-high level for a time-interval longer than tWD_DIS prior to the moment the device releases the nRSTOUT pin. If the Watchdog Disable function is activated in this way, the device sets bit WD_PWRHOLD to keep the watchdog in the Long Window. The watchdog stays in the Long Window until the MCU clears the WD_PWRHOLD bit.
In case the MCU needs to be reprogrammed while the watchdog monitors the correct operation of the MCU, the MCU can set bit WD_RETURN_LONGWIN to put the watchdog back in the Long Window. When the MCU set this bit, the watchdog returns to the Long Window after the current Watchdog Sequence completes. In order to make the watchdog stay in the Long Window as long as needed the MCU can either re-configure the Long Window (tLONG_WINDOW) time interval, or set the WD_PWRHOLD bit. Once the MCU starts the first watchdog sequence (as described in Section 8.3.11.3), the MCU must clear bit WD_RETURN_LONGWIN before the end of the first watchdog sequence in order to continue the watchdog sequence operation.