Smart Module Series
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1. When the module is powered on for the first time, its timing of turning on may be different from that
shown above.
2. Make sure that VBAT is stable before pulling down PWRKEY. It is recommended to wait until VBAT to
be stable at 3.8 V for at least 30 ms before pulling down PWRKEY. Additionally, PWRKEY cannot be
kept pulled down all the time.
3.5.2. Turn off the Module
Drive the PWRKEY pin low for at least 1 s, and then choose to turn off the module when the prompt
window comes up.
You can also force the module to power off by driving PWRKEY low for at least 8 s. The forced
power-down scenario is illustrated in the following figure.
VBAT
PWRKEY
Others
> 8 s
Power down
Figure 8: Timing of Turning off the 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 VBAT. The external power source can be a
rechargeable battery (such as a coin cell) according to application demands. A reference circuit design is
shown below.
NOTES