CY7C924ADX-AC Cypress Semiconductor Corp, CY7C924ADX-AC Datasheet - Page 23

• Manufacturer Part Number: CY7C924ADX-AC
• Manufacturer: Cypress Semiconductor Corp

Specifications of CY7C924ADX-AC

• Number Of Transceivers: 1
• Data Rate: 622Mbps
• Operating Supply Voltage (typ): 5V
• Supply Current (max): 250mA
• Screening Level: Commercial
• Pin Count: 100
• Mounting: Surface Mount
• Package Type: TQFP
• Operating Supply Voltage (min): 4.5V
• Operating Supply Voltage (max): 5.5V
• Operating Temperature (min): 0C
• Operating Temperature (max): 70C
• Lead Free Status / RoHS Status: Not Compliant

Document #: 38-02008 Rev. *E
allows one or more sources to send data to multiple receivers
with the receivers connected in a ring or daisy-chain topology.
By prefacing cells containing data with an address field, it is
possible to have each receiver only process data specifically
directed to it.
Byte-Unpacker
The Byte-Unpacker is used to reassemble 10-bit characters
from a received stream of decoded 8-bit characters. This
reassembly process is designed to allow transmission of the
same embedded commands, serial addresses, and Start of
Cell markers that are used with 8-bit data characters. Because
of the change in time per received encoded character versus
delivered 10-bit data character, this unpacking process is only
possible with the Receive FIFO enabled.
The byte-unpacker reverses the character segmentation
shown in Figure 4. It takes five data characters and combines
them into four 10-bit characters. This five-state unpacking
process is re-started by the detection of any Special Character
code in the Decoder, including the C5.0 (K28.5) fill character.
Since usage of the Elasticity Buffer inserts and deletes C5.0
characters (as necessary) to handle the speed differences
between the receive and transmit character clocks, it is not
possible to send byte-packed data through the Elasticity
Buffer. To send 10-bit packed data from one source to multiple
destinations it is necessary to either use a star topology of
interconnect, or make use of the buffered and reclocked serial
input-to-output connections controlled by the Routing Matrix.
Receive Control State Machine
The Receive Control State Machine responds to multiple input
conditions to control the routing and handling of received
characters. It controls the staging of characters across various
registers and the Receive FIFO. It also interprets all
embedded Special Character codes, and converts the appro-
priate ones to specific bit combinations in the Receive FIFO.
It controls the various discard policies and error control within
the receiver, and operates in response to:
These signals and conditions are used by the Receive Control
State Machine to control the Receive Formatter, write access
to the Receive FIFO, write access to the Elasticity Buffer, the
Byte-Unpacker, the Receive Output register, and BIST. They
determine the content of the characters passed to each of
these destinations,
The Receive Control State Machine always operates
synchronous to the recovered character clock (bit-clock/10 or
bit-clock/12). When the Receive FIFO is bypassed, RXCLK
becomes an output that changes synchronous to the internal
character clock. RXCLK operates at the same frequency as
the internal character clock.
• the received character stream
• the detection and validation of serial addresses
• the room for additional data in the Receive FIFO
• the state of the receiver BIST enable (RXBISTEN*)
• the state of LOOPTX
• the state of FIFOBYP*.
Discard Policies
When the Receive FIFO is enabled, the Receive Control State
Machine has the ability to selectively discard specific
characters from the data stream that are determined by the
present configuration as being unnecessary. When discarding
is enabled, it reduces the host system overhead necessary to
keep the Receive FIFO from overflowing and losing data.
The discard policy is configured as part of the operating mode
and is set using the RXMODE[1:0] inputs. The four discard
policies are listed in
Table 7. Receiver Discard Policies
Policy 0 is the simplest and also applies for all conditions
where the Receive FIFO is bypassed. In this mode, every
character that is received is placed into the Receive FIFO
(when enabled) or into the Receive Output Register.
In discard policy 1, all Start Of Cell, extended command, and
serial address commands are processed as they are received.
The C5.0 character, which is automatically transmitted when
no data is present in the Transmit FIFO, is treated differently
here. In this mode, whenever two or more adjacent C5.0
characters are received, all of them are discarded except the
last one received before any other character type. This allows
these fill characters to be removed from the data stream, but
does not change the data flow for protocols (like Fibre
Channel) that use a single C5.0 character as a delimiter.
Policy 2 is identical to policy 1 except that all C5.0 characters
are removed from the data stream.
Policy 3 is a super-set of policy 2, where the serial address is
also discarded.
When the FIFOs are bypassed (FIFOBYP* LOW), no
characters are actually discarded, but the receiver discard
policy can be used to control external filtering of the data. The
RXEMPTY* FIFO flag is used to indicate if the character on
the output bus is valid or not. In discard policy 0, the
RXEMPTY* flag is always deasserted to indicate that valid
data is always present. In discard policy 1 when a series of
C5.0 characters are received, the RXEMPTY* flag indicates
an empty condition for all but the last C5.0 character before
any other character is presented. In discard policies 2 or 3, the
RXEMPTY* flag indicates an empty condition for all C5.0
characters. When any other character is present, this flag
indicates that valid or “interesting” Data or Special Characters
are present.
Receive FIFO
The Receive FIFO is used to buffer data captured from the
selected serial stream for later processing by the host system.
Policy # RXMODE[1:0] Policy Description
0
1
2
3
00
01
10
11
Table
7.
Keep all received characters
Process Commands, discard all
but the last C5.0 character
Process Commands, discard all
C5.0 characters
Process Commands, discard all
C5.0 characters, discard serial
addresses
CY7C924ADX
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