In addition to the various methods of reducing power in active mode, the ARM7 core supports various power reduction modes including Idle, Sleep, and Power Down. In Idle mode, the core is stopped but the peripherals remain in operation. In Sleep mode, the MCU receives no internal clocks whatsoever but the processor state is retained with the registers, logic levels, and RAM content.The Flash and RTC remain as well, unless disabled. With the internal RC (IRC) oscillator, the MCU can come out of Sleep mode in only four clock cycles. Finally, Power Down mode is very similar to Sleep mode except that the Flash and RTC are both turned off. With an IRC, the MCU can wake up in 60 μs + 4 clock cycles.