SCAN25100TYA/NOPB National Semiconductor, SCAN25100TYA/NOPB Datasheet - Page 18

• Manufacturer Part Number: SCAN25100TYA/NOPB
• Description: IC SERIAL/DESERIAL CPRI 100-TQFP
• Manufacturer: National Semiconductor
• Series: SCANr

Specifications of SCAN25100TYA/NOPB

• Function: Serializer/Deserializer
• Data Rate: 2.5Gbps
• Input Type: LVTTL/LVCMOS
• Output Type: LVTTL, LVCMOS
• Number Of Inputs: 10
• Number Of Outputs: 10
• Voltage - Supply: 1.7 V ~ 1.9 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 100-TQFP Exposed Pad, 100-eTQFP, 100-HTQFP, 100-VQFP
• Operating Temperature (min): -40C
• Operating Temperature Classification: Industrial
• Operating Temperature (max): 85C
• Package Type: TQFP EP
• Rad Hardened: No
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: SCAN25100TYA

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WRITE MODE (RXCLKMODE = 0)
In write mode, RXCLK is the recovered clock output. The pins
ROUT[9:0], CDET, LOCKB, and LOS are synchronous to
RXCLK.
READ MODE (RXCLKMODE = 1)
In read mode, RXCLK is an input and the pins ROUT[9:0],
CDET, LOCKB, and LOS are latched by the RXCLK input
SYSCLK AND RE REMOTE RADIO HEAD
SYNCHRONIZATION
The SCAN25100 has independent transmit and receive PLLs
as well as an internal ~30.72 MHz oscillator for seamless RE
synchronization. Once the SCAN25100 locks to incoming
CPRI data, SysCLK becomes phase locked to the recovered
clock, automatically synchronizing the RE to the REC. This
phase lock transition occurs gracefully through analog circuit-
ry to allow downstream components to track the slight fre-
FIGURE 5. Write Mode and Read Mode Diagram
18
strobe. Note that for read mode, RXCLK must be syn-
chronous to the incoming serial data stream to avoid receiver
FIFO over- and underflow. Read mode is recommended for
1228.8 and 614.4 Mbps rates only.
quency change from external clock to recovered clock. During
RE synchronization, TxCLK (and RxCLK if in read mode)
should be held static high or low to prevent FIFO over- or un-
der- flow
Unlike most SerDes, the SCAN25100 deserializer does not
depend on RefCLK . RefCLK can therefore be switched from
a local clock source (crystal oscillator) to the recovered clock
without the deserializer losing lock.
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