Vrtc Interface - Quectel SC600Y-EM Series Hardware Design

VBAT
PWRKEY
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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
rechargeable battery (such as coil cells) according to application demands. The following reference circuit
design when an external battery is utilized for powering RTC.
If RTC is ineffective, it can be synchronized through network after the module is powered on.
⚫ 2.0V~3.25V input voltage range and 3.0V typical value for VRTC, when VBAT is disconnected.
⚫ When powered by VBAT, the RTC error is 50ppm. When powered by VRTC, the RTC error is about
200ppm.
⚫ If the rechargeable battery is used, the ESR of battery should be less than 2K, and it is
recommended to use the MS621FE FL11E of SEIKO.
SC600Y&SC600T_Hardware_Design
Figure 9: Timing of Turning off Module
Coin Cell
Figure 10: RTC Powered by Coin Cell
SC600Y&SC600T Hardware Design
> 8s
Power down
VRTC
Module
Smart LTE Module Series
RTC
Core
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