The pushbutton function implemented through the TSMR pin has three main functions. First, it serves as a means to wake the device from ultra-low power modes like ship mode. Second, it serves as a short button press detector, sending an interrupt to the host when the button driving the TSMR pin has been pressed for Wake1, Wake2, or long press durations. This allows the implementation of different functions in the end application such as menu selection and control. Finally it serves as a means to get the device into ship mode or reset the system by performing a power cycle/ hardware reset (shut down SYS and automatically powering it back on) after detecting a long button press. The timing for the short and long button press duration is programmable through I²C for added flexibility and allows system designers to customize the end user experience of a specific application. Note that if a specific timer duration is changed through I²C while that timer is active and has not expired, the new programmed value will be ignored until the timer expires and/or is reset by new push button action. In battery only mode the device will automatically pulse the TSMR current source ON for t_{TS_DUTY_ON} duration and turn it OFF for t_{TS_DUTY_OFF} duration to check if a button is pressed. If a button press is registered, the device will begin counting against Wake1, Wake2 or long press durations. This button press detection routine in battery only mode is run as long as it is enabled by the EN_PUSH bit. When a valid adapter is present, the TSMR current source is always ON to monitor charging.