Low-power modes

　　The STM32F103xC, STM32F103xD and STM32F103xE performance line supports three

　　low-power modes to achieve the best compromise between low power consumption, short

　　startup time and available wakeup sources:

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　　Sleep mode

　　In Sleep mode, only the CPU is stopped. All peripherals continue to operate and can

　　wake up the CPU when an interrupt/event occurs.

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　　Stop mode

　　Stop mode achieves the lowest power consumption while retaining the content of

　　SRAM and registers. All clocks in the 1.8 V domain are stopped, the PLL, the HSI RC

　　and the HSE crystal oscillators are disabled. The voltage regulator can also be put

　　either in normal or in low-power mode.

　　The device can be woken up from Stop mode by any of the EXTI line. The EXTI line

　　source can be one of the 16 external lines, the PVD output, the RTC alarm or the USB

　　wakeup.

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　　Standby mode

　　The Standby mode is used to achieve the lowest power consumption. The internal

　　voltage regulator is switched off so that the entire 1.8 V domain is powered off. The

　　PLL, the HSI RC and the HSE crystal oscillators are also switched off. After entering

　　Standby mode, SRAM and register contents are lost except for registers in the Backup

　　domain and Standby circuitry.

　　The device exits Standby mode when an external reset (NRST pin), an IWDG reset, a

　　rising edge on the WKUP pin, or an RTC alarm occurs.

　　Note:

　　The RTC, the IWDG, and the corresponding clock sources are not stopped by entering Stop

　　or Standby mode.