SBAS495 – JUNE 2010
DIR: Auto Source Selector for Main Output and AUX Output
The AUTO source selector is an automatic system that selects the DIR or ADC output based on specific DIR
conditions set by Register 26h. The AUTO source selector is integrated in both the Main Port and the AUX
The typical behavior for the AUTO source selector is shown in
setting for Register 26h. In this case, only Register 26h/AUNLOCK is selected.
XTI (ADC) Source
Figure 30. Typical Behavior for AUTO Source Selector
When the DIR is unlocked, the ADC output is automatically routed to the Main Output Port.
Polarity of the CLKST signal is configured by Register 22h/CLKSTP. The default is active low, which means that
clock source either changes from DIR to ADC, or from ADC to DIR.
If the DIR is locked, then the DIR output is routed to the Main Output Port automatically after t
period, the output port is muted. t
providing that an XTI clock of 24.576 MHz is applied.
If the DIR loses its lock a subsequent time, the ADC output is routed to the Main Output Port automatically after
. Once again, the output port is muted during this time. t
The auto source selector can be triggered by the following changes in the DIR (Register 26h is used to select
which variable to use as the trigger):
DIR error (discussed earlier in
DIR: Errors and
Out-of-range sampling frequency
When the Validity flag in the S/PDIF stream is '1'
When the PLL is unlocked (default)
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30. This example is the default register
can be configured using Register 23h/ERRWT[1:0]. t
can be configured using Register
Interrupts; configured by Register 25h)
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XTI (ADC) Source
. During that
is 50 ms,
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