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SIM548C Hardware Design
SIM548C_HD_V1.01
09.05.2008
67
Figure 34: Turn on the GPS module
4.5 The theory of the GPS RTC circuit
The RTC is very important for the GPS module, because the data kept in the SRAM is depended
on the VRTC. Please keep the VRTC on if you want to use the function of hotstart, warmstart, or
Push-To-Fix mode. There is a RTC LDO in our SIM548C module; it can provide 1.5V voltage to
the SRAM. The theory of RTC circuit is shown in the following figure: