A simplified state diagram is shown on this slide. The LTC2956 can be configured to power up automatically in either RUN mode (with the wake-up timer running) or SHUTDOWN mode (with the wake-up timer stopped). If powered up in RUN mode, the LTC2956 cycles between the awake and sleep states. During the awake state, the EN pin is pulled high to turn the system on and the failsafe ONMAX timer is started. The awake state is exited only if the task is completed (and a microprocessor pulls the SLEEP input pin low) or if the ONMAX timer expires. During the sleep state, the EN pin is pulled low to turn the system off and the LTC2956 exits the sleep state only if the wake-up timer expires or if the system is forced on, either with a short pushbutton press or a microprocessor pulling SLEEP high. The LTC2956 will exit any state and enter SHUTDOWN mode if a long pushbutton press is detected. When powered up in SHUTDOWN mode, all system components, except for the LTC2956 which is in a very low power mode, are powered down to conserve energy. This mode is particularly useful for products that are shipped with their batteries installed, such as a smoke alarm. From this mode, a short pushbutton press is required to turn on the system and start the wake-up timer in RUN mode. Whenever the LTC2956 goes from SHUTDOWN to RUN mode, the ONALERT input pin is pulled low to notify a system to perform a power-up initialization routine. Similarly, whenever the LTC2956 goes from RUN to SHUTDOWN mode, the OFFALERT output pin is pulled low to alert the system before shutdown, or connected to an LED to provide visual indication of system on/off status.