Nokia 8208, Руководство по обслуживанию

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RM-384
System Module and User Interface
Page 5-26 Company Confidential Issue1
Copyright © 2009 Nokia. All rights reserved.
SLEEP Crystal Circuit for 32.768kHz
The MSM6800A device contains a sleep oscillator circuit used as a clock source when other clocks are disabled to
conserve power.
Bits 11:10 of MPM_CLK_SLEEPOSC control the gain of the internal inverter in the MSM6800A device’s sleep
oscillator circuit. Bits 11:10 are collectively called SLEEP_OSC_GAIN.
Table 33 Sleep oscillator Inverter relative gain settings
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Bit 9 of MPM_CLK_SLEEPOSC, called SLEEP_OSC_RF_BYPASS controls the feedback resistance between the input
and output of the internal inverter.
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Set (1) SLEEP_OSC_RF_BYPASS to disable the feedback path.
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Clear (0) SLEEP_OSC_RF_BYPASS to enable the feedback path.
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Bit 8 of MPM_CLK_SLEEPOSC, called SLEEP_OSC_RD_BYPASS controls the series resistance between
the output of the internal inverter, and the SLEEP_XTAL_OUT pin.
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Set (1) this bit to disable series resistance between the inverter’s output and the SLEEP_XTAL_OUT pin.
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Clear (0) this bit to enable that series resistance.
Figure 65 Sleep oscillator circuit with passive crystal