Smart Wi-Fi Module Series
SC20-WL Hardware Design
SC20-WL_Hardware_Design
34 / 81
VBAT
PWRKEY
Others
>8s
Power down
Figure 9: Timing of Turning off Module
3.6. VRTC Interface
The RTC (Real Time Clock) can be powered by an external power source through VRTC when the
module is powered down and there is no power supply for the VBAT. The external power source can be
capacitor or rechargeable battery (such as coil cells) according to application demands. The following are
some reference circuit designs when an external battery or capacitor is utilized for powering RTC.
Module
RTC
Core
VRTC
Coin Cell
Figure 10: RTC Powered by Coin Cell
Large
Capacitance
Capacitor
Module
RTC
Core
VRTC
C
Figure 11: RTC Powered by Capacitor