Rtc Backup - SimCom SIM5300E Hardware Design


Receive a voice or data call from network.

Receive a SMS from network.
Note: The first byte of the user's data will not be recognized.
4.5

RTC BACKUP

When VBAT is not supplied to the system, the current is supplied to RTC as input. When VBAT power supply
is in present and the backup battery is in low voltage state, the current is supplied to backup battery as
output. The RTC power supply of module can be provided by an external capacitor or a battery
(non-chargeable or rechargeable) through the VRTC. The following figures show various reference circuits for
RTC back up.

External capacitor backup

Non-chargeable battery backup

Rechargeable battery backup
SIM5300E_Hardware_Design_V1.02
Large-capacitance
Capacitor
Figure 17: RTC supply from capacitor
Non-chargeable
Backup Battery
Figure 18: RTC supply from non-chargeable battery
Rechargeable
Backup Battery
Figure 19: RTC supply from rechargeable battery
MODULE
VRTC 1.5K
RTC
Core
MODULE
VRTC 1.5K
RTC
Core
MODULE
1.5K
VRTC
RTC
Core
24