Clocking Scheme - Nokia 6720 Service Manual

RM-424; RM-564
System Module

Clocking scheme

In BB5.44, two main clocks are provided to the system: 38.4MHz RF clock produced by VCTCXO in the RF section
and 32.768kHz sleep clock produced by EM ASIC N2200 with an external crystal.
32 k Sleep Clock is always powered on after startup. Sleep clock is used by RAPU for low-power operation.
SMPS Clk is 3.2MHz clock line from RAPU to EM ASIC N2200. In deep sleep mode, when VCTCXO is off, this signal
is set to '0'-state.
CLK600. The clock source is an internal RC oscillator in EM ASIC N2200 (during the power-up sequence) or
RAPU SMPS Clk.
Bluetooth has a separate 38.4MHz TCXO clock oscillator.
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