DS90UR124Q_14 Datasheet, PDF (18/36 Pages) Texas Instruments – MHz DC-Balanced 24-Bit FPD-Link II Serializer and Deserializer Chipset

DS90UR124Q, DS90UR241Q
SNLS231N – SEPTEMBER 2006 – REVISED MARCH 2013
www.ti.com
Functional Description
The DS90UR241 Serializer and DS90UR124 Deserializer chipset is an easy-to-use transmitter and receiver pair
that sends 24-bits of parallel LVCMOS data over a single serial LVDS link from 120 Mbps to 1.03 Gbps
throughput. The DS90UR241 transforms a 24-bit wide parallel LVCMOS data into a single high speed LVDS
serial data stream with embedded clock and scrambles / DC Balances the data to enhance signal quality to
support AC coupling. The DS90UR124 receives the LVDS serial data stream and converts it back into a 24-bit
wide parallel data and recovered clock. The 24-bit Serializer/Deserializer chipset is designed to transmit data up
to 10 meters over shielded twisted pair (STP) at clock speeds from 5 MHz to 43MHz.
The Deserializer can attain lock to a data stream without the use of a separate reference clock source; greatly
simplifying system complexity and overall cost. The Deserializer synchronizes to the Serializer regardless of data
pattern, delivering true automatic “plug and lock” performance. It will lock to the incoming serial stream without
the need of special training patterns or sync characters. The Deserializer recovers the clock and data by
extracting the embedded clock information and validating data integrity from the incoming data stream and then
deserializes the data. The Deserializer monitors the incoming clock information, determines lock status, and
asserts the LOCK output high when lock occurs.
In addition the Deserializer also supports an optional @SPEED BIST (Built In Self Test) mode, BIST error flag,
and LOCK status reporting pin. Signal quality on the wide parallel output is controlled by the SLEW control and
bank slew (PTOSEL) inputs to help reduce noise and system EMI. Each device has a power down control to
enable efficient operation in various applications.
INITIALIZATION AND LOCKING MECHANISM
Initialization of the DS90UR241 and DS90UR124 must be established before each device sends or receives
data. Initialization refers to synchronizing the Serializer’s and Deserializer’s PLL’s together. After the Serializers
locks to the input clock source, the Deserializer synchronizes to the Serializers as the second and final
initialization step.
Step 1: When V_DD is applied to both Serializer and/or Deserializer, the respective outputs are held in TRI-STATE
and internal circuitry is disabled by on-chip power-on circuitry. When V_DD reaches V_DD OK (~2.2V) the PLL in
Serializer begins locking to a clock input. For the Serializer, the local clock is the transmit clock, TCLK. The
Serializer outputs are held in TRI-STATE while the PLL locks to the TCLK. After locking to TCLK, the Serializer
block is now ready to send data patterns. The Deserializer output will remain in TRI-STATE while its PLL locks to
the embedded clock information in serial data stream. Also, the Deserializer LOCK output will remain low until its
PLL locks to incoming data and sync-pattern on the RIN± pins.
Step 2: The Deserializer PLL acquires lock to a data stream without requiring the Serializer to send special
patterns. The Serializer that is generating the stream to the Deserializer will automatically send random (non-
repetitive) data patterns during this step of the Initialization State. The Deserializer will lock onto embedded clock
within the specified amount of time. An embedded clock and data recovery (CDR) circuit locks to the incoming bit
stream to recover the high-speed receive bit clock and re-time incoming data. The CDR circuit expects a coded
input bit stream. In order for the Deserializer to lock to a random data stream from the Serializer, it performs a
series of operations to identify the rising clock edge and validates data integrity, then locks to it. Because this
locking procedure is independent on the data pattern, total random locking duration may vary. At the point when
the Deserializer’s CDR locks to the embedded clock, the LOCK pin goes high and valid RCLK/data appears on
the outputs. Note that the LOCK signal is synchronous to valid data appearing on the outputs. The Deserializer’s
LOCK pin is a convenient way to ensure data integrity is achieved on receiver side.
DATA TRANSFER
After Serializer lock is established, the inputs DIN0–DIN23 are used to input data to the Serializer. Data is
clocked into the Serializer by the TCLK input. The edge of TCLK used to strobe the data is selectable via the
TRFB pin. TRFB high selects the rising edge for clocking data and low selects the falling edge. The Serializer
outputs (DOUT±) are intended to drive point-to-point connections.
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