Power Saving Mode - SIM Tech SIMCom SIM800C Hardware Design

Note: Autobauding is default. It cannot enter sleep mode in the absence of synchronous serial port baud rate
after module power on.

4.4. Power Saving Mode

Current input for RTC when the VBAT is not supplied for the system. Current output for backup battery when
the VBAT power supply is in present and the backup battery is in low voltage state. 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
Large-capacitance
Capacitor

Non-chargeable battery backup
Non-chargeable
Backup Battery

Rechargeable battery backup
Rechargeable
Backup Battery
SIM800C_Hardware_Design_V1.00
Figure 15: RTC supply from capacitor
Figure 16: RTC supply from non-chargeable battery
VRTC
Figure 17: RTC supply from rechargeable battery
Module
VRTC
2.2K
Module
VRTC
2.2K
Module
2.2K
24
Smart Machine Smart Decision
RTC
Core
RTC
Core
RTC
Core
2014-10-30