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Smart Module Series
SC200R Series Hardware Design
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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.
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.
Figure 9: RTC Powered by Coin Cell
If RTC is ineffective, it can be synchronized through the network after the module is powered on. The
recommended input voltage range for VRTC is 2.0–3.25 V and the recommended typical value is 3.0 V.