ep2sgx30c Altera Corporation, ep2sgx30c Datasheet - Page 27

• Manufacturer Part Number: ep2sgx30c
• Description: Stratix Ii Gx Device Data Sheet
• Manufacturer: Altera Corporation

Altera Corporation
October 2007
The CRU has a built-in switchover circuit to select whether the PLL VCO
is aligned by the reference clock or the data. The optional port
rx_freqlocked monitors when the CRU is in locked-to-data mode.
In the automatic mode, the CRU PLL must be within the prescribed PPM
frequency threshold setting of the CRU reference clock for the CRU to
switch from locked-to-reference to locked-to-data mode.
The automatic switchover circuit can be overridden by using the optional
ports rx_locktorefclk and rx_locktodata.
possible combinations of these two signals.
If the rx_locktorefclk and rx_locktodata ports are not used, the
default is auto mode.
Deserializer (Serial-to-Parallel Converter)
The deserializer converts a serial bitstream into 8, 10, 16, or 20 bits of
parallel data. The deserializer receives the LSB first.
the deserializer.
Table 2–6. Receiver Lock Combinations
rx_locktodata
0
0
1
rx_locktorefclk
0
1
x
Stratix II GX Device Handbook, Volume 1
Stratix II GX Architecture
VCO (Lock to Mode)
Table 2–6
Reference clock
Figure 2–17
Auto
Data
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