10.6 Battery Back-up
This application note describes how to back-up the RTC and the SRAM of the GPS
receiver module. The basics of the first example addresses providing a back-up
power supply by using a separate battery or a “Supercap”.
While the “Supercap” is charged through the module during normal operation, the
battery (primary cell) is decoupled thru a diode!
Figure 18: Application note: Module back-up
An alternative to this solution is to switch the supply voltage from the Vcc pin to the
Vbat pin. Care needs to be taken that there is no voltage outage during the switch-
over phase!
The Vbak pin draws 20 µA typically.
V1.5 – Dec-09
User’s Manual
Page 32 of 37
