User's Manual

GSM/GPRS/GNSS Module Series
MC60 Hardware Design
MC60_Hardware_Design Confidential / Released 32 / 99
3.3.4. Monitor Power Supply
The command AT+CBC can be used to monitor the supply voltage of the GSM part. The unit of the
displayed voltage is mV.
For details, please refer to document [1].
3.3.5. Backup Domain of GNSS
The RTC (Real Time Clock) function of GSM part and backup mode of GNSS part are supported. In
GNSS’s backup mode, the backup domain which contains all the necessary GNSS information for quick
start-up and a small amount of user configuration variables is alive. Due to the backed-up memory, EASY
technology is available.
3.3.5.1. Use VBAT as the Backup Power Source of GNSS
In either all-in-one or stand-alone solution, GNSS’s backup mode will be active as long as the main power
supply (VBAT) is remained, even when the module is turned off and GNSS_VCC is powered off; as the
GNSS’s backup domain is powered by VBAT. In this case, the VRTC pin can be kept floating.
When powered by VBAT, the reference internal circuit design in all-in-one and stand-alone solutions is
shown below.
Figure 11: Internal GNSS’s Backup Domain Power Construction
3.3.5.2. Use VRTC as Backup Power of GNSS
In either all-in-one or stand-alone solution, when the main power supply (VBAT) is removed after the
module is turned off, and GNSS_VCC is also powered off, a backup supply such as a coin-cell battery
(rechargeable or non-chargeable) or a super capacitor can be used to power the VRTC pin to keep GNSS