Tcxo - Nokia 1265 Description And Troubleshooting

Nokia Customer Care

TCXO

The MSM device integrates a phase-locked loop from the TCXO clock input.
The PM optimizes TCXO operation that enables and disables appropriate circuits in
the proper sequence.
When the selected transition occurs at TCXO_EN, the controller quickly enables the
TCXO regulator and the input buffer, and begins counting SLEEP_CLK pulses.
Within an initial power on period, the TCXO will be stabilized to its own calibrated
frequency. This initial period, in units of 32.768 kHz clock pulses, is programmed into
a timer within the controller. When the timer expires, the output buffer is enabled. It
synchronizes with the TCXO input such that the TCXO_OUT signal is glitch free,
only valid TCXO pulses are output.
The input buffer (TCXO_IN) accepts sinusoidal or square wave signals at or near
19.2 MHz. The input buffer (TCXO_IN) is powered from the TCXO regulator while
the output buffer is powered by VREG_MSMP.
The regulator of TCXO is turned off after the TCXO_EN signal is removed. Upon
power-up, the PM defaults to this SBI-controlled mode with the TCXO defaulted on.
This assures the MSM will always have a clock available immediately at power-up
even if TCXO_EN is low.
TCXO waveform (19.2MHz +/-2ppm)
Issue 1 04/2007
The controller is enabled by the signal from the MSM.
Figure 5: TCXO Enable Timing Diagram
© 2007 Nokia Corporation
Baseband Description and Troubleshooting
Company Confidential
1265 (RH-103)
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