LG -C300 Service Manual page 29

3. TECHNICAL BRIEF
3.2.8 Sysclock Switching
The PMU controls the rf_sysclk_en signal of the DCXO in the RF macro. During startup the PMU enables
the DCXO. After the system is running the DCXO is controlled by the SCU of the baseband by using the
vcxo_enable signal. This is handled by a dedicated logic in the PMU, see Figure 21. As long as
rf_sysclk_en_pmu, the output of the PMU state-machine is high, vcxo_enable controls the rf_sysclk_en
signal to the RF. If rf_sysclk_en_pmu is low, the DXCO is switched off, independent from vcxo_enable.
LGE Internal Use Only
Figure 3.2.4 PMU, CGU and External Reset
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3. TECHNICAL BRIEF
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