The device is powered-down in the OFF state, and a battery power supply may or may not be available for the device. If a valid power source is available, and if the WAKE pin is driven low, the only active circuit in the device is the WAKE input detection circuit to reduce device power consumption.

The device goes into the OFF state because of either a CLR_WAKE_LATCH command from the MCU or any global OFF-state condition as listed in Device Fail-Safe Controller State Diagram. All global OFF state conditions are latched in the analog wake-up detection circuit and serves two purposes. The first purpose is to preserve the root-cause information for an OFF state shutdown (or system shutdown). The information is latched in the Analog_Latch, and is passed on to the digital core during the next device power-up event. The system MCU can verify the information by reading bits in the OFF_STATE_L register and the corresponding status bits defined in Table 11-14. The second purpose is to prevent auto-restart when the device auto-start is disabled and the device enters the OFF state while the WAKE pin is still driven above its V_WAKE-ON threshold level. If the device was powered down because of a failure either in the device or in the system and the device auto-start is disabled, then the device can be enabled, only when a new rising edge is detected at the WAKE pin which is an indication of the user trying to restart the system. After each new power-up event, information in the Analog_Latch is copied to the respective SPI-mapped status registers in the digital core.

The device auto-start behavior can be configured through the AUTO_START_DIS latch. This latch is physically located in the analog wake-up detection circuit. The AUTO_START_DIS latch is cleared to 0b during the device NPOR event only if a NPOR event was preceded by loss of battery supply at the VIN, VINA, and VIN_SAFE pins. This bit is set to 1b by the system MCU through the SET_AUTO_START_DIS SPI command or when a valid VREG OV event is detected. If the AUTO_START_DIS latch is set to 1b and if the device goes into the OFF state because of one of the global OFF state conditions is detected and while the WAKE pin is still driven above its V_WAKE-ON threshold level, then the device does not restart until the WAKE pin is driven below its V_WAKE-ON threshold level and then driven above its V_WAKE-ON threshold level.

The analog wake-up circuit implements a filter to prevent false device power-up because of noise at the WAKE input. When a valid WAKE input is detected, the filtered signal is latched in the analog power latch (AN_WAKEUP_L) followed by a check of the supply voltage at the VIN pin while the device overtemperature check is performed after EEPROM download in the RESET state. The device can continue with the power-up sequence and goes into the INIT state only if the supply voltage is greater than the minimum required voltage level for the power-up and when there is no junction overtemperature condition (junction temperature is less than the warning threshold level). Otherwise, the device goes back to the OFF state and clears the AN_WAKEUP_L latch and latch failure conditions (VIN UV, over-temperature, or both) in the Analog_Latch.

When the device is in the OFF state, the NRES and ENDRV/nIRQ outputs are driven low even if the supply at the supply pins are less than the minimum required level for the device power-up.