This slide illustrates all of the sources for system reset including a brownout reset BOR, a power on reset POR, and a power up clear PUC. Different events trigger these reset signals and different initial conditions exist depending on which source triggered the reset. Similar to the F5xx Flash family, the FR59xx features seven operating modes for standby operation ranging from LPM0 to LPM4.5. The modes are selected based on the need for clock frequency, power requirements and the type of peripheral that needs to be enabled while in standby. This slide also shows the various system power consumption numbers when the device is in modes LPM0, LPM3, LPM4, LPM3.5 and LPM4.5. Selecting the right mode is easy: LPM0 is an ideal choice for applications using a high frequency timer to trigger an interrupt allowing the CPU to be turned off while still providing for a fast wakeup. LPM3 is the preferred mode for low frequency peripherals. It allows the operation of the RTC crystal while consuming less than 700 nA. In LPM4 all the system clocks are turned off and a device wakeup is possible only from an external interrupt such as a switch triggering a port pin. LPM3.5 and LPM4.5 are more specialized modes that allow the digital core to be turned off while retaining minimal functionality allowing the device to hibernate. LPM3.5 is the lowest standby power mode in which the device can maintain a real time clock, wake up on clock or alarm events, or from a switch interrupt. The wake up time from this mode is longer than the typical LPMs because the core regulator that was switched off on entry needs to be powered back on. LPM4.5 is also known as deep-shelf mode, an example application where this mode is used – is to store battery powered products that are stored in warehouses before shipping to an end-user, the products are required to consume extremely low power while maintaining the ability to wake up from a switch interrupt. Both LPM3.5 and LPM4.5 are ideal for applications that have low duty cycle and slow response time events. In such applications maximizing time in LPMx.5 can reduce power consumption significantly.