The INH pin is a high voltage output pin that provides voltage from the VSUP minus a diode drop to enable an external high voltage regulator. These regulators are usually used to support the microprocessor and VIO pin. The INH function is on in all modes except for sleep mode. In sleep mode the INH pin is turned off, going into a high Z state. This allows the node to be placed into the lowest power state while in sleep mode. If this function is not required it can be disabled by setting register 8'h1A = 1b using the SPI interface. If this function is not required, TCAN1144-Q1 and TCAN1146-Q1 can configure this pin as a LIMP home pin by setting register 8'h1A = 1b. When configured as the LIMP pin it is connected to external circuitry for a limp home mode. If the Watchdog times out, the device by default turns on the LIMP home function. To turn off LIMP three consecutive (default) correct watchdog input triggers must take place. The number of correct watchdog input triggers can be changed to one using LIMP_SEL_RESET, register 8'h1A[3:2] = 01b. If fail-safe mode is enabled, any event that causes the device to enter this mode causes the LIMP pin to turn on if LIMP is enabled. Writing a 1b to 8'h1A, LIMP_RESET, can be used to turn off the LIMP pin.
This terminal should be considered a "high voltage logic" terminal, not a power output; thus it should be used to drive the EN terminal of the system’s power management device and not used as a switch for power management supply itself. This terminal is not reverse battery protected and thus should not be connected outside of the system module.