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Nations Technologies Inc.
Tel
:
+86-755-86309900
:
Address: Nations Tower, #109 Baoshen Road, Hi-tech Park North.
Nanshan District, Shenzhen, 518057, P.R.China
into a deep sleep state. When SW1 switches the power supply system to VBAT, it indicates that VDD has
been powered down at this time.
When reset, SW1 will switch the power supply system to the VDD power supply area. In STOP2, STANDBY
and VBAT modes, the internal voltage regulator BKR will power the digital backup area.
During the VDD rising phase or when PDR is detected, the switch between VBAT and VDD remains
connected to the VBAT area.
During startup, if VDD is settling quickly and VDD > VBAT + 0.6V, current can be injected to VBAT
through the internal diode connection. If the power supply connected to VBAT or the battery does not
support this injection of current. It is strongly recommended to add a low voltage diode between this supply
and the VBAT pin.
If there is no external battery in the application. It is recommended to connect the VBAT pin to VDD with a
100nF ceramic capacitor. In RUN, SLEEP, STOP0 mode, the backup area is powered by VDD (SW1 is
connected to VDD), the following functions are available:
PC14 and PC15 can be used for common IO ports or LSE pins
PC13 can be used for common IO port, TAMPER pin, RTC check clock pin, RTC alarm and periodic wake-
up output
Notice:
Due to the fact that the current flowing through SW1 and SW2 is limited to a maximum of 3mA. Therefore, the
IO output modes of PA0_WAKUP, PC13 to PC15 are limited. When a 30PF capacitor is attached, the maximum
output speed is 2MHz. In addition, these IOs cannot be driven by current, for example, they cannot drive LEDs.
The current of SW2 will be maintained at 3mA or lower, because GPIO, and EXTI work together to consume
current.
When VBAT supplies power to the backup area, the following functions can be used at this time:
PC14 and PC15 can only be used for LSE pins.
PC13 is used for TAMPER pin, RTC alarm or periodic wake-up output