CYPRESS CY7C9689A

CY7C9689A
TAXI™-compatible HOTLink Transceiver
The CY7C9689A HOTLink Transceiver is a point-to-point
communications building block allowing the transfer of data
over high-speed serial links (optical fiber, balanced, and unbalanced copper transmission lines) at speeds ranging between
50 and 200 MBaud. The transmit section accepts parallel data
of selectable widths and converts it to serial data, while the
receiver section accepts serial data and converts it to parallel
data of selectable widths. Figure 1 illustrates typical connections between two independent host systems and corresponding CY7C9689A parts. The CY7C9689A provides
enhanced technology, increased functionality, a higher level of
integration, higher data rates, and lower power dissipation
over the AMD AM7968/7969 TAXIchip products.
Framer
Deserializer
Decoder
4B/5B, 5B/6B
Control
HOTLink devices are ideal for a variety of applications where
parallel interfaces can be replaced with high-speed,
point-to-point serial links. Some applications include interconnecting workstations, backplanes, servers, mass storage, and
video transmission equipment.
Serial Link
Serializer
Data
Transmit
Encoder
4B/5B, 5B/6B
Status
Serial Link
Transmit
Data
Control
CY7C9689A
CY7C9689A
FIFO
Transmit
System Host
Data
Receive
FIFO
Receive
The transmit section of the CY7C9689A HOTLink can be
configured to accept either 8- or 10-bit data characters on each
clock cycle, and stores the parallel data into an internal
synchronous Transmit FIFO. Data is read from the Transmit
FIFO and is encoded using embedded 4B/5B or 5B/6B
The TTL parallel I/O interface may be configured as either a
FIFO (configurable for depth expansion through external
FIFOs) or as a pipeline register extender. The FIFO configurations are optimized for transport of time-independent
(asynchronous) 8- or 10-bit character-oriented data across a
link. A Built-In Self-Test (BIST) pattern generator and checker
allows for testing of the high-speed serial data paths in both
the transmit and receive sections, and across the interconnecting links.
Status
System Host
Functional Description
The integrated 4B/5B and 5B/6B encoder/decoder may be
bypassed (disabled) for systems that present externally
encoded or scrambled data at the parallel interface. With the
encoder bypassed, the pre-encoded parallel data stream is
converted to and from a serial NRZI stream. The embedded
FIFOs may also be bypassed (disabled) to create a
reference-locked serial transmission link. For those systems
requiring even greater FIFO storage capability, external FIFOs
may be directly coupled to the CY7C9689A through the
parallel interface without the need for additional glue-logic.
Transmit
FIFO
•
•
•
•
•
Receive
FIFO
•
Encoder
4B/5B, 5B/6B
•
•
The receive section of the CY7C9689A HOTLink accepts a
serial bit-stream from one of two PECL compatible differential
line receivers and, using a completely integrated PLL Clock
Synchronizer, recovers the timing information necessary for
data reconstruction. The recovered bit stream is converted
from NRZI to NRZ, deserialized, framed into characters,
4B/5B or 5B/6B decoded, and checked for transmission
errors. The recovered 8- or 10-bit decoded characters are then
written to an internal Receive FIFO, and presented to the
destination host system.
Decoder
4B/5B, 5B/6B
•
•
Second-generation HOTLink® technology
AMD™ AM7968/7969 TAXIchip™-compatible
8-bit 4B/5B or 10-bit 5B/6B NRZI encoded data transport
10-bit or 12-bit NRZI pre-encoded (bypass) data
transport
Synchronous TTL parallel interface
Embedded/bypassable 256-character Transmit and
Receive FIFOs
50- to 200-MBaud serial signaling rate
Internal phase-locked loops (PLLs) with no external
PLL components
Dual differential PECL-compatible serial inputs and
outputs
Compatible with fiber-optic modules and copper cables
Built-In Self-Test (BIST) for link testing
Link Quality Indicator
Single +5.0V ±10%supply
100-pin TQFP
Deserializer
Framer
•
•
•
•
encoders to improve its serial transmission characteristics.
These encoded characters are then serialized, converted to
NRZI, and output from two PECL-compatible differential transmission line drivers at a bit-rate of either 10 or 20 times the
input reference clock in 8-bit (or 10-bit bypass) mode, or 12 or
24 times the reference clock in 10-bit (or 12-bit bypass) mode.
Serializer
Features
Receive
Data
Figure 1. HOTLink System Connections
Cypress Semiconductor Corporation
Document #: 38-02020 Rev. *C
•
3901 North First Street
•
San Jose, CA 95134
•
408-943-2600
Revised November 7, 2002
CY7C9689A
TAXI HOTLink Transceiver Logic Block Diagram
TX
STATUS
TXDATA/TXCMD CONTROL
TXCLK
MODE
REFCLK
10
RX
STATUS
RXDATA/RXCMD
RXCLK
13
8
13
3
4
Mode
Control
Output Register
MUX
MUX
Output Register
Input Register
Flags
Mode
Receive
FIFO
Flags
Transmit
FIFO
CONTROL
CE
TXEN
RXEN
TXHALT
TXRST
RXRST
RFEN
TXBISTEN
RXBISTEN
RESET
Transmit
PLL Clock
Multiplier
MUX
Pipeline Register
MUX
Pipeline Register
Receive
Control
State
Machine
BIST LFSR
4B/5B, 5B/6B Encoder
Transmit
Control
State
Machine
MUX
Serial Shifter
Bit Clock
MODE
RANGESEL
SPDSEL
RXMODE[1:0]
FIFOBYP
EXTFIFO
ENCBYP
BYTE8/10
TEST
BIST LFSR
4B/5B, 5B/6B Decoder
Clock
Divider
Deserializer
Framer
Receive
Clock/Data
Recovery
Bit Clock
RXSTATUS
LFI
RXEMPTY
RXHALF
RXFULL
TX STATUS
TXEMPTY
TXHALF
TXFULL
Routing Matrix
Signal
Validation
DLB
Document #: 38-02020 Rev. *C
OUTA
INA
OUTB
CURSETB
CURSETA
INB
A/B
CARDET
Page 2 of 46
CY7C9689A
VSSA
RXBISTEN
CURSETB
VSSA
VDDA
OUTB+
OUTB–
VSSA
VSSA
INB–
INB+
VDDA
VDDA
OUTA+
OUTA–
VSSA
VSSA
INA–
INA+
VDDA
VDDA
CURSETA
VDDA
VSSA
CARDET
Pin Configuration
TEST
1
100 99 98 97 96 95 94 93 92 91 90 89 88 87 86 85 84 83 82 81 80 79 78 77 76
75
A/B
2
74
RANGESEL
LFI
3
73
RFEN
VSS
4
72
TXFULL
DLB
5
71
CE
VLTN
6
70
TXHALF
TXBISTEN
7
69
RXEN
RXCLK
8
68
TXCLK
TXHALT
9
67
RXRST
RXFULL
10
66
VSS
VSS
11
65
RXSC/D
REFCLK
12
64
VDD
VSS
13
63
VSS
VDD
14
62
VDD
VSS
15
61
RXDATA[0]
TXRST
16
60
TXEMPTY
VDD
17
59
RXDATA[1]
CY7C9689A
SPDSEL
Document #: 38-02020 Rev. *C
RESET
BYTE8/10
EXTFIFO
RXDATA[3]
RXDATA[4]
51
26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
TXDATA[8]/TXCMD[3]
25
RXDATA[5]
VSS
RXMODE[0]
TXDATA[7]
52
RXDATA[6]
24
TXDATA[6]
RXDATA[2]
RXMODE[1]
RXDATA[7]
53
TXDATA[5]
23
VSS
TXDATA[9]/TXCMD[2]
RXDATA[11]/RXCMD[1]
VSS
54
VSS
22
TXDATA[4]
VDD
TXDATA[0]
VDD
55
TXDATA[3]
21
RXDATA[8]/RXCMD[3]
TXCMD[0]
RXEMPTY
TXDATA[2]
56
RXDATA[9]/RXCMD[2]
20
TXDATA[1]
VSS
TXSC/D
RXDATA[10]/RXCMD[0]
TXCMD[1]
57
FIFOBYP
58
19
VSS
18
ENCBYP
TXEN
RXHALF
Page 3 of 46
CY7C9689A
(
Pin Descriptions
Pin
Name
I/O Characteristics
Signal Description
Transmit Path Signals
68
TXCLK
TTL clock input
Internal Pull-up
Transmit FIFO Clock.
Used to sample all Transmit FIFO and related interface signals.
44, 42, TXDATA[7:0]
40, 36,
34, 32,
30, 22
TTL input, sampled on Parallel Transmit DATA Input.
TXCLK↑ or REFCLK↑ When selected (CE = LOW and TXEN = asserted), information on these inputs
is processed as DATA when TXSC/D is LOW and ignored otherwise. When the
Internal Pull-up
encoder is bypassed (ENCBYP is LOW), TXDATA[7:0] functions as the least
significant eight bits of the 10- or 12-bit pre-encoded transmit character.
When the Transmit FIFO is enabled (FIFOBYP is HIGH), these inputs are
sampled on the rising edge of TXCLK. When the Transmit FIFO is bypassed
(FIFOBYP is LOW) these inputs are captured on the rising edge of REFCLK.
54, 46 TXDATA[9:8]/
TXCMD[2:3]
TTL input, sampled on Parallel Transmit DATA or COMMAND Input.
TXCLK↑ or REFCLK↑ When selected, BYTE8/10 is HIGH, and the encoder is enabled (ENCBYP is
HIGH), information on these inputs are processed as TXCMD[2:3] if TXSC/D is
Internal Pull-up
HIGH and ignored otherwise.
When selected, BYTE8/10 is LOW, and the encoder is enabled (ENCBYP is
HIGH), information on these inputs are processed as TXDATA[9:8] if TXSC/D
is LOW and ignored otherwise.
When the encoder is bypassed (ENCBYP is LOW), TXDATA[9:8] functions as
the 9th and 10th bits of the 10- or 12-bit pre-encoded transmit character.
When the Transmit FIFO is enabled (FIFOBYP is HIGH), these inputs are
sampled on the rising edge of TXCLK. When the Transmit FIFO is bypassed
(FIFOBYP is LOW), these inputs are captured on the rising edge of REFCLK.
58, 56 TXCMD[1:0]
TTL input, sampled on Parallel Transmit COMMAND Input.
TXCLK↑ or REFCLK↑ When selected and the encoder is enabled (ENCBYP is HIGH), information on
these inputs is processed as a COMMAND when TXSC/D is HIGH and ignored
Internal Pull-up
otherwise.
When BYTE8/10 is HIGH and the encoder is bypassed (ENCBYP is LOW), the
TXCMD[1:0] inputs are ignored.
When BYTE8/10 is LOW and when the encoder is bypassed (ENCBYP is
LOW), the TXCMD[1:0] inputs function as the 11th and 12th (MSB) bits of the
12-bit pre-encoded transmit character.
When the Transmit FIFO is enabled (FIFOBYP is HIGH), these inputs are
sampled on the rising edge of TXCLK. When the Transmit FIFO is bypassed
(FIFOBYP is LOW), these inputs are sampled on the rising edge of REFCLK.
20
TTL input, sampled on COMMAND or DATA input selector.
TXCLK↑ or REFCLK↑ When selected, BYTE8/10 is HIGH, and the encoder is enabled (ENCBYP is
Internal Pull-up
HIGH), this input selects if the DATA or COMMAND inputs are processed. If
TXSC/D is HIGH, the value on TXCMD[3:0] is captured as one of sixteen
possible COMMANDs, and the data on the TXDATA[7:0] bits are ignored. If
TXSC/D is LOW, the information on TXDATA[7:0] is captured as one of 256
possible 8-bit DATA values, and the information on the TXCMD[3:0] bus is
ignored.
When BYTE8/10 is LOW and the encoder is enabled (ENCBYP is HIGH) this
input selects if the DATA or COMMAND inputs are processed. If TXSC/D is
HIGH, the information on TXCMD[1:0] is captured as one of four possible
COMMANDs, and the information on the TXDATA[9:0] bits are ignored. If
TXSC/D is LOW, the information on TXDATA[9:0] is captured as one of 1024
possible 10-bit DATA values, and the information on the TXCMD[1:0] bus is
ignored.
When the encoder is bypassed (ENCBYP is LOW) TXSC/D is ignored
TXSC/D
Document #: 38-02020 Rev. *C
Page 4 of 46
CY7C9689A
Pin Descriptions (continued)
Pin
Name
I/O Characteristics
Signal Description
18
TXEN
TTL input, sampled on Transmit Enable.
TXCLK↑ or REFCLK↑ TXEN is sampled on the rising edge of the TXCLK or REFCLK input and enables
parallel data bus write operations (when selected). The device is selected when
Internal Pull-up
TXEN is asserted during a clock cycle immediately following one in which CE
is sampled LOW.
Depending on the level on EXTFIFO, the asserted state for TXEN can be active
HIGH or active LOW. If EXTFIFO is LOW, then TXEN is active LOW and data
is captured on the same clock cycle where TXEN is sampled LOW. If EXTFIFO
is HIGH, then TXEN is active HIGH and data is captured on the clock cycle
following any clock edge when TXEN is sampled HIGH.
7
TXBISTEN
TTL input,
asynchronous
Internal Pull-up
16
TXRST
TTL input, sampled on Reset Transmit FIFO.
TXCLK↑
When the Transmit FIFO is enabled (FIFOBYP is HIGH), TXEN is deasserted,
CE is asserted (LOW), and TXRST is sampled LOW by TXCLK for seven cycles,
Internal Pull-up
the Transmit FIFO begins its internal reset process. The Transmit FIFO TXFULL
flag is asserted and the host interface counter and address pointer are zeroed.
This reset propagates to the serial transmit side, any remaining counters and
pointers. The TXFULL flag is asserted until both sides of the Transmit FIFO
have reset. While TXRST remains asserted, the Transmit FIFO remains in reset
and the TXFULL output remains asserted.
When the Transmit FIFO is bypassed (FIFOBYP is LOW), TXRST is ignored.
9
TXHALT
TTL input, sampled on Transmitter Halt Control Input.
TXCLK↑
When TXHALT is asserted LOW, transmission of data is suspended and the
HOTLink TAXI transmits SYNC characters. When TXHALT is deasserted HIGH,
Internal Pull-up
normal data processing proceeds.
If the Transmit FIFO is enabled (FIFOBYP is HIGH), the interface is allowed to
continue loading data into the Transmit FIFO while TXHALT is asserted.
72
TXFULL
Three-state TTL
output, changes
following TXCLK↑ or
REFCLK↑
Transmit FIFO Full Status Flag.
When the Transmit FIFO is enabled (FIFOBYP is HIGH) and its flags are driven
(CE is LOW), TXFULL is asserted when four or fewer characters can be written
to the HOTLink Transmit FIFO. If a Transmit FIFO reset has been initiated
(TXRST was sampled asserted for a minimum of seven TXCLK cycles),
TXFULL is asserted to enforce the full/unavailable status of the Transmit FIFO
during reset.
When the Transmit FIFO is bypassed (FIFOBYP is LOW), the TXFULL output
changes after the rising edge of REFCLK. TXFULL is asserted when the transmitter is BUSY (not accepting a new data or command characters) and
deasserted when new characters can be accepted.
When the Transmit FIFO is bypassed and RANGESEL is HIGH or SPDSEL is
LOW, TXFULL toggles at the character rate to provide a character rate
reference control-indication since REFCLK is operating at twice of the data rate.
The asserted state of this output (HIGH or LOW) is determined by the state of
the EXTFIFO input. When EXTFIFO is LOW, TXFULL is active LOW. When
EXTFIFO is HIGH, TXFULL is active HIGH.
70
TXHALF
Three-state TTL
output, changes
following TXCLK↑
Transmit FIFO Half-full Status Flag.
When the Transmit FIFO is enabled (FIFOBYP is HIGH and CE is LOW)
TXHALF is asserted when the HOTLink Transmit FIFO is half full (128
characters is half full). If a Transmit FIFO reset has been initiated (TXRST was
sampled asserted for a minimum of seven TXCLK cycles), TXHALF is asserted
to enforce the full/unavailable status of the Transmit FIFO during reset.
When the Transmit FIFO is bypassed (FIFOBYP is LOW), TXHALF remains
deasserted, having no logical function.
TXHALF is forced to the High-Z state only during a “full-chip” reset (i.e., while
RESET is LOW).
Document #: 38-02020 Rev. *C
Transmitter BIST Enable.
When TXBISTEN is LOW, the transmitter generates a 511-character repeating
sequence that can be used to validate link integrity. This 4B/5B BIST sequence
is generated regardless of the state of other configuration inputs. The transmitter returns to normal operation when TXBISTEN is HIGH. All Transmit FIFO
read operations are suspended when BIST is active.
Page 5 of 46
CY7C9689A
Pin Descriptions (continued)
Pin
60
Name
I/O Characteristics
TXEMPTY
Three-state TTL
output, changes
following TXCLK↑ or
REFCLK↑
Signal Description
Transmit FIFO Empty Status Flag.
When the Transmit FIFO is enabled (FIFOBYP is HIGH and CE is LOW),
TXEMPTY is asserted when the HOTLink Transmit FIFO has no data to forward
to the encoder. If a Transmit FIFO reset has been initiated (TXRST was sampled
asserted for a minimum of seven TXCLK cycles), TXEMPTY is deasserted and
remains deasserted until the Transmit FIFO reset operation is complete.
When the Transmit FIFO is bypassed (FIFOBYP is LOW), TXEMPTY is
asserted to indicate that the transmitter can accept data. TXEMPTY is also used
as a BIST progress indicator when TXBISTEN is asserted.
When TXBISTEN is asserted LOW, TXEMPTY becomes the transmit BIST-loop
counter indicator (regardless of the logic state of FIFOBYP). In this mode
TXEMPTY is asserted for one TXCLK or REFCLK period at the end of each
transmitted BIST sequence.
Note: During BIST operations, when the Transmit FIFO is enabled (FIFOBYP
is HIGH), it is necessary to keep TXCLK operating, even though no data is
loaded into the Transmit FIFO and TXEN is never asserted, to allow the
TXEMPTY flag to respond to the BIST state changes.
The asserted state of this output (HIGH or LOW) is determined by the state of
the EXTFIFO input. When EXTFIFO is LOW, TXEMPTY is active LOW. When
EXTFIFO is HIGH, TXEMPTY is active HIGH.
If CE is sampled asserted (LOW), TXEMPTY is driven to an active state. If CE
is sampled deasserted (HIGH), TXEMPTY is placed into a High-Z state.
Receive Path Signals
8
RXCLK
Bidirectional TTL clock Receive Clock.
Internal Pull-up
When the Receive FIFO is enabled (FIFOBYP is HIGH), this clock is the
Receive interface input clock and is used to control Receive FIFO read and
reset, operations. When the Receive FIFO is bypassed (FIFOBYP is LOW), this
clock becomes the recovered Receive PLL character clock output which runs
continuously at the character rate.
41, 43, RXDATA[7:0]
45, 47,
48, 53,
59,61
Three-state TTL
output, changes
following RXCLK↑
Parallel Receive DATA Outputs.
When the decoder is enabled (ENCBYP is HIGH), the low-order eight bits of
the decoded DATA character are presented on the RXDATA[7:0] outputs.
COMMAND characters, when they are received, do not disturb these outputs.
When the decoder is bypassed, the low order eight bits of the non-decoded
character are presented on the RXDATA[7:0] outputs.
When the Receive FIFO is disabled (FIFOBYP is LOW), these outputs change
on the rising edge of the RXCLK output. When the Receive FIFO is enabled
(FIFOBYP is HIGH), these outputs change on the rising edge of RXCLK input.
RXEN is the three-state control for RXDATA[7:0].
31, 33 RXDATA[9:8]/
RXCMD[2:3]
Three-state TTL
output, changes
following RXCLK↑
Parallel Receive DATA or COMMAND Output.
When BYTE8/10 is HIGH and the decoder is enabled (ENCBYP is HIGH) these
outputs reflects the value for the most recently received RXCMD[2:3].
When BYTE8/10 is LOW and the decoder is enabled (ENCBYP is HIGH) these
outputs reflects the value for the most recently received RXDATA[9:8].
When the decoder is bypassed (ENCBYP is LOW), RXDATA[9:8] functions as
the 9th and 10th bits of the 10- or 12-bit non-decoded receive character.
When the Receive FIFO is disabled (FIFOBYP is LOW), these outputs change
on the rising edge of the RXCLK output. When the Receive FIFO is enabled
(FIFOBYP is HIGH), these outputs change on the rising edge of the RXCLK
input.
RXEN is a three-state control for RXDATA[9:8]/RXCMD[2:3].
Document #: 38-02020 Rev. *C
Page 6 of 46
CY7C9689A
Pin Descriptions (continued)
Pin
Name
I/O Characteristics
23, 29 RXDATA[11:10 Three-state TTL
]/RXCMD[1:0] output, changes
following RXCLK↑
Signal Description
Parallel Receive COMMAND Outputs.
When the decoder is enabled (ENCBYP is HIGH) these outputs reflect the value
for the most recently received RXCMD[1:0].
When BYTE8/10 is HIGH and the decoder is bypassed (ENCBYP is LOW),
these outputs have no meaning and are driven LOW.
When BYTE8/10 is LOW and the decoder is bypassed (ENCBYP is LOW),
RXCMD[1:0] functions as the 11th and 12th (MSB) bits of the 12-bit
non-decoded receive character.
When the Receive FIFO is disabled (FIFOBYP is LOW), this output changes
on the rising edge of the RXCLK output. When the Receive FIFO is enabled
(FIFOBYP is HIGH), these outputs change on the rising edge of the RXCLK
input.
RXEN is a three-state control for RXCMD[1:0].
69
RXEN
TTL input, sampled
on RXCLK↑
Internal Pull-up
Receive Enable Input.
RXEN is a three-state control for the parallel data bus read operations. RXEN
is sampled on the rising edge of the RXCLK input (or output) and enables
parallel data bus read operations (when selected). The device is selected when
RXEN is asserted during an RXCLK cycle immediately following one in which
CE is sampled LOW. The parallel data pins are driven to active levels after the
rising edge of RXCLK. When RXEN is de-asserted (ending the selection) the
parallel data pins are High-Z after the rising edge of RXCLK.
Depending on the level on EXTFIFO, this signal can be active HIGH or active
LOW. If EXTFIFO is LOW, then RXEN is active LOW. If EXTFIFO is HIGH, then
RXEN is active HIGH. Data is delivered on the clock cycle following any clock
edge when RXEN is active.
65
RXSC/D
Three-state TTL
output, changes
following RXCLK↑
COMMAND or DATA Output Indicator.
When BYTE8/10 is HIGH and the decoder is enabled (ENCBYP is HIGH), this
output indicates which group of outputs have been updated. If RXSC/D is HIGH,
RXCMD[3:0] contains a new COMMAND. The DATA on the RXDATA[7:0] pins
remain unchanged. If RXSC/D is LOW, RXDATA[7:0] contains a new DATA
character. The COMMAND output on RXCMD[3:0] remain unchanged.
When BYTE8/10 is LOW and the decoder is enabled (ENCBYP is HIGH), this
output indicates which group of outputs have been updated. If RXSC/D is HIGH,
RXCMD[1:0] contains a new COMMAND and the DATA on the RXDATA[9:0]
remain unchanged. If RXSC/D is LOW, RXDATA[9:0] contains a new DATA
character and the COMMAND output on RXCMD[1:0] remain unchanged.
When the decoder is bypassed (ENCBYP is LOW) RXSC/D is not used and
may be left unconnected.
RXEN is a three-state control for RXSC/D.
6
VLTN
Three-state TTL
output, changes
following RXCLK↑
Internal Pull-down
Code Rule Violation Detected.
VLTN is asserted in response to detection of a 4B/5B or 5B/6B character that
does not meet the coding rules of these characters. When VLTN is asserted,
the values on the output DATA and COMMAND buses remain unchanged.
VLTN remains asserted for one RXCLK period.
VLTN is used to report character mismatches when RXBISTEN is driven LOW.
VLTN is driven LOW when the decoder is bypassed (ENCBYP is LOW).
RXEN is a three-state control for VLTN.
67
RXRST
TTL input, sampled on Receive FIFO Reset. Active LOW.
RXCLK↑
When the Receive FIFO is enabled (FIFOBYP is HIGH), RXEN is deasserted,
Internal Pull-up
CE is asserted (LOW), and RXRST is sampled while asserted (LOW) by RXCLK
for seven cycles, the Receive FIFO begins its internal reset process.
Once the reset operation is started, the RXEMPTY flag is asserted and the
interface counters and address pointer are zeroed. The reset operation
proceeds to clear out the internal write pointers and counters. The RXEMPTY
output remains asserted through the reset operation and remains asserted until
new data is written to the Receive FIFO. While RXRST remains asserted, the
Receive FIFO remains in reset and cannot accept received characters.
When the Receive FIFO is bypassed (FIFOBYP is LOW), RXRST is ignored.
Document #: 38-02020 Rev. *C
Page 7 of 46
CY7C9689A
Pin Descriptions (continued)
Pin
Name
I/O Characteristics
24, 25 RXMODE[1:0] Static control input
TTL levels
Normally wired HIGH
or LOW
Signal Description
Receiver Discard Policy Mode Select.
00b—allows all characters to be written into the Receive FIFO or output to the
Receive data bus
01b—discards all JK or LM sync characters except the “last” one of a string of
sync characters. Single sync characters in a data stream are included in the
data written into the Receive FIFO.
1Xb—discards all JK or LM sync characters. The data stream written into the
Receive FIFO does not include sync characters.
77
RXBISTEN
TTL input,
asynchronous
Internal Pull-up
Receiver BIST Enable. Active LOW.
When LOW, the receiver is configured to perform a character-for-character
match of the incoming data stream with a 511-character BIST sequence. The
result of character mismatches are indicated on the VLTN pin. Completion of
each 511-character BIST loop is accompanied by an assertion pulse on the
RXFULL flag.
The state of ENCBYP, FIFOBYP, and BYTE8/10 have no effect on BIST
operation.
73
RFEN
TTL input,
asynchronous
Internal Pull-up
Reframe Enable.
Used to control when the framer is allowed to adjust the character boundaries
based on detection of one or more framing characters in the data stream.
When framing is enabled (RFEN is HIGH) the receive framer realigns the serial
stream to the incoming 10-bit JK sync character (if BYTE8/10 is HIGH) or the
12-bit LM sync character (if BYTE8/10 is LOW). Framing is disabled when
RFEN is LOW. The deassertion of RFEN freezes the character boundary
relationship between the serial stream and character clock. RFEN is an
asynchronous input, sampled by the internal Receive PLL character clock.
10
RXFULL
Three-state TTL
output, changes
following RXCLK↑
Receive FIFO Full Flag.
When the Receive FIFO is enabled (FIFOBYP is HIGH) and its flags are driven
(CE is LOW), RXFULL is asserted when space is available for four or fewer
characters to be written to the HOTLink Receive FIFO. If the RXCLK input is
not continuous or the FIFO is accessed at a rate slower than data is being
received, RXFULL may also indicate that some data has been lost because of
FIFO overflow.
When the Receive FIFO is bypassed (FIFOBYP is LOW), RXFULL is
deasserted to indicate that valid data may be present. RXFULL is also used as
a BIST progress indicator, and pulses once every pass through the 511
character BIST loop.
When RXBISTEN is asserted (LOW), RXFULL becomes the receive BIST loop
progress indicator (regardless of the logic state of FIFOBYP). While RXBISTEN
is asserted, RXFULL is asserted until the receiver detects the start of the BIST
pattern. Then RXFULL is deasserted for the duration of the BIST pattern,
pulsing asserted for one RXCLK period on the last symbol of each BIST loop.
If 14 of 28 consecutive symbols are received in error, RXFULL returns to the
asserted state until the start of a BIST pattern is again detected.
The asserted state of this output (HIGH or LOW) is determined by the state of
the EXTFIFO input. When EXTFIFO is LOW, RXFULL is active LOW. When
EXTFIFO is HIGH, RXFULL is active HIGH.
19
RXHALF
Three-state TTL
output, changes
following RXCLK↑
Receive FIFO Half-full Flag.
When the Receive FIFO is enabled (FIFOBYP is HIGH and CE is LOW)
RXHALF is asserted when the HOTLink Receive FIFO is half full (128
characters is half full). If a Receive FIFO reset has been initiated (RXRST was
sampled asserted for a minimum of seven RXCLK cycles), RXHALF is
deasserted to enforce the empty/unavailable status of the Receive FIFO during
reset. If FIFOBYP is LOW, RXHALF remains deasserted having no logical
function.
RXHALF is forced to the High-Z state only during a “full-chip” reset (i.e., while
RESET is LOW).
Document #: 38-02020 Rev. *C
Page 8 of 46
CY7C9689A
Pin Descriptions (continued)
Pin
21
Name
RXEMPTY
I/O Characteristics
Three-state TTL
output, changes
following RXCLK↑
Signal Description
Receive FIFO Empty Flag.
When the Receive FIFO is enabled (FIFOBYP is HIGH) and its flags are driven
(CE is LOW), RXEMPTY is asserted when the HOTLink Receive FIFO has no
data to forward to the parallel interface. If a Receive FIFO reset has been
initiated (RXRST was sampled asserted for a minimum of seven RXCLK
cycles), RXEMPTY is asserted to enforce the empty/unavailable status of the
Receive FIFO during reset.
Any read operation occurring when RXEMPTY is asserted results in no change
in the FIFO status, and the data from the last valid read remains on the RXDATA
bus. When the Receive FIFO is bypassed but the decoder is enabled,
RXEMPTY is used as a valid data indicator. When deasserted it indicates that
valid data is present at the RXDATA or RXCMD outputs as indicated by
RXSC/D. When asserted it indicates that a SYNC character (JK or LM) is
present on the RXCMD output pins. When the Receive FIFO is bypassed
(FIFOBYP is LOW), RXEMPTY is deasserted whenever data is ready.
The asserted state of this output (HIGH or LOW) is determined by the state of
the EXTFIFO input. When EXTFIFO is LOW, RXEMPTY is active LOW. When
EXTFIFO is HIGH, RXEMPTY is active HIGH.
Control Signals
71
CE
TTL input sampled on Chip Enable Input. Active LOW.
TXCLK↑, RXCLK↑, or When CE is asserted and sampled LOW by RXCLK, the Receive FIFO status
flags are driven to their active states. When this input is deasserted and sampled
REFCLK↑
by RXCLK, the Receive FIFO status flags are placed in a High-Z state.
When CE has been sampled LOW and RXEN changes from deasserted to
asserted and is sampled by RXCLK, the RXSC/D, RXDATA[7:0], RXDATA[9:8]/
RXCMD[2:3] and VLTN output drivers are enabled and go to their driven levels.
These pins remain driven until RXEN is sampled deasserted.
When the Transmit FIFO is enabled (FIFOBYP is HIGH), and CE is asserted
and sampled by TXCLK, the Transmit FIFO status flags are driven to their active
states. When this input is deasserted and sampled by TXCLK, the Transmit
FIFO status flags are placed in a High-Z state.
When the Transmit FIFO is bypassed (FIFOBYP is LOW), and CE is asserted
and sampled by REFCLK, the Transmit FIFO status flags are driven to their
active states. When this input is deasserted and sampled by REFCLK, the
Transmit FIFO status flags are placed in a High-Z state.
When the Transmit FIFO is enabled (FIFOBYP is HIGH), CE has been sampled
LOW, and TXEN changes from deasserted to asserted and is sampled by
TXCLK, the TXSC/D, TXDATA[7:0], TXDATA[9:8]/RXCMD[2:3], and
TXCMD[1:0] inputs are sampled and passed to the Transmit FIFO. These inputs
are sampled on all consecutive TXCLK cycles until TXEN is sampled
deasserted.
When the Transmit FIFO is bypassed (FIFOBYP is LOW), CE has been
sampled LOW, and TXEN changes from deasserted to asserted and is sampled
by REFCLK, the TXSC/D, TXDATA[7:0], TXDATA[9:8]/RXCMD[2:3], and
TXCMD[1:0] inputs are sampled and passed to the encoder or serializer as
directed by other control inputs. These inputs are sampled on all consecutive
REFCLK cycles until TXEN is sampled deasserted.
12
REFCLK
TTL clock input
PLL Frequency Reference Clock.
This clock input is used as the timing reference for the transmit and receive
PLLs. When the Transmit FIFO is bypassed (FIFOBYP is HIGH), REFCLK is
also used as the clock for the parallel transmit interface.
75
SPDSEL
Static control input
TTL levels
Normally wired HIGH
or LOW
Speed Select.
Used to select from one of two operating serial rates for the CY7C9689A. When
SPDSEL is HIGH, the signaling rate is between 100 and 200 MBaud. When
LOW, the signaling rate is between 50 and 100 MBaud. Used in combination
with RANGESEL and BYTE8/10 to configure the VCO multipliers and dividers.
Document #: 38-02020 Rev. *C
Page 9 of 46
CY7C9689A
Pin Descriptions (continued)
Pin
Name
I/O Characteristics
Signal Description
74
RANGESEL
Static control input
TTL levels
Normally wired HIGH
or LOW
Range Select.
Selects the proper prescaler for the REFCLK input. If RANGESEL is LOW, the
REFCLK input is passed directly to the Transmit PLL clock multiplier. If
RANGESEL is HIGH, REFLCK is divided by two before being sent to the
Transmit PLL multiplier.
When the Transmit FIFO is bypassed (FIFOBYP is LOW), with RANGESEL
HIGH or SPDSEL LOW, TXFULL toggles at half the REFCLK rate to provide a
character rate indication, and to show when data can be accepted.
51
RESET
Asynchronous
TTL input
Master Reset for Internal Logic.
Pulsed LOW for one or more REFCLK cycles.
28
FIFOBYP
Static control input
TTL levels
Normally wired HIGH
or LOW
FIFO Bypass Enable.
When asserted, the Transmit and Receive FIFOs are bypassed. In this mode
TXCLK is not used. Instead all transmit data must be synchronous to REFCLK.
Transmit FIFO status flags are synchronized to REFCLK. All received data is
synchronous to RXCLK output. Receive FIFO status flags are synchronized to
RXCLK (the recovered Receive PLL character clock).
When not asserted, the Transmit and Receive FIFOs are enabled. In this mode
all Transmit FIFO writes are synchronized to TXCLK, and all Receive FIFO
reads are synchronous to the RXCLK input.
50
BYTE8/10
Static control input
TTL levels
Normally wired HIGH
or LOW
8/10-bit Parallel Data Size Select.
When set for 8-bit data (BYTE8/10 is HIGH) and the encoder is enabled
(ENCBYP is HIGH), 8-bit DATA characters and 4-bit COMMAND characters are
captured at the TXDATA[7:0] or TXCMD[3:0] inputs (selected by the TXSC/D
input) and passed to the Transmit FIFO (if enabled) and encoder. Received
characters are decoded, passed through the Receive FIFO (if enabled) and
presented at either the RXDATA[7:0] or RXCMD[3:0] outputs and indicated by
the RXSC/D output.
When set for 8-bit data (BYTE8/10 is HIGH) and the encoder is bypassed
(ENCBYP is LOW), the internal data paths are set for 10-bit characters. Each
received character is presented to the Receive FIFO (if enabled) and is passed
to the RXDATA[9:0] outputs.
When set for 10-bit data (BYTE8/10 is LOW) and the encoder is enabled
(ENCBYP is HIGH), 10-bit DATA characters and 2-bit COMMAND characters
are captured at the TXDATA[9:0] or TXCMD[1:0] inputs (selected by the
TXSC/D input) and passed to the Transmit FIFO (if enabled) and encoder.
Received characters are decoded, passed through the Receive FIFO (if
enabled) and presented at either the RXDATA[9:0] or RXCMD[1:0] outputs and
indicated by the RXSC/D output.
When set for 10-bit data (BYTE8/10 is LOW) and the encoder is bypassed
(ENCBYP is LOW), the internal clock data paths are set for 12-bit characters.
Each received character is presented to the Receive FIFO (if enabled) and is
passed to the RXDATA[9:0] and the RXCMD[1:0] outputs.
49
EXTFIFO
Static control input
TTL levels
Normally wired HIGH
or LOW
External FIFO Mode.
EXTFIFO modifies the active state of the RXEN and TXEN inputs and the timing
of the Transmitter and Receiver data buses. When configured for external
FIFOs (EXTFIFO is HIGH), TXEN is assumed to be driven by the empty flag of
an attached CY7C42X5 FIFO, and RXEN is assumed to be driven by the almost
full flag of an attached CY7C42X5 FIFO. In this mode the active data transition
is in the clock following the clock edge that “enables” the data bus.
When not configured for external FIFOs (EXTFIFO is LOW), TXEN is assumed
to be driven as a pipeline register and RXEN is assumed to be driven by a
controller for a pipeline register. In this mode the active data transition is within
the same clock as the clock edge that “enables” the data bus.
EXTFIFO also modifies the output state of the Receive and Transmit FIFO flags.
When configured for external FIFOs (EXTFIFO is HIGH), the Full and Empty
FIFO flags are active HIGH (the Half full flag is always active LOW). When not
configured for external FIFOs (EXTFIFO is LOW), all of the FIFO flags are active
LOW.
Document #: 38-02020 Rev. *C
Page 10 of 46
CY7C9689A
Pin Descriptions (continued)
Pin
27
Name
ENCBYP
I/O Characteristics
Static control input
TTL levels
Normally wired HIGH
or LOW
Signal Description
Enable Encoder Bypass Mode.
When asserted, both the encoder and decoder are bypassed. Data is transmitted without 4B/5B or 5B/6B encoding (but with NRZI encoding), LSB first.
Received data are presented as parallel characters to the parallel interface
without decoding.
When deasserted, data is passed through both the encoder in the Transmit path
and the decoder in the Receive path.
Analog I/O and Control
89, 90, OUTA±
81, 82 OUTB±
PECL compatible
differential output
Differential Serial Data Outputs.
These PECL-compatible differential outputs are capable of driving terminated
transmission lines or commercial fiber-optic transmitter modules. To minimize
the power dissipation of unused outputs, the outputs should be left unconnected
and the associated CURSETA or CURSETB should be connected to VDD.
94, 93, INA±
86, 85 INB±
PECL compatible
differential input
Differential Serial Data Inputs.
These inputs accept the serial data stream for deserialization and decoding.
Only one serial stream at a time may be fed to the receive PLL to extract the
data content. This stream is selected using the A/B input.
97
CURSETA
Analog
Current-set Resistor Input for OUTA±.
A precision resistor is connected between this input and a clean ground to set
the output differential amplitude and currents for the OUTA± differential driver.
78
CURSETB
Analog
Current-set Resistor Input for OUTB±.
A precision resistor is connected between this input and a clean ground to set
the output differential amplitude and currents for the OUTB± differential driver.
100
CARDET
PECL input,
asynchronous
Carrier Detect Input.
Used to allow an external device to signify a valid signal is being presented to
the high-speed PECL input buffers, as is typical on an Optical Module. When
CARDET is deasserted LOW, the LFI indicator asserts LOW signifying a Link
Fault. This input can be tied HIGH for copper media applications.
2
A/B
Asynchronous TTL
input
Input A or Input B Selector.
When HIGH, input INA± is selected, when LOW, INB± is selected.
3
LFI
TTL output, changes
following RXCLK↑
Link Fault Indication Output. Active LOW.
LFI changes synchronous with RXCLK. This output is driven LOW when the
serial link currently selected by A/B is not suitable for data recovery. This could
be because:
Serial Data Amplitude is below acceptable levels
Input transition density is not sufficient for PLL clock recovery
Input Data stream is outside an acceptable frequency range of operation
CARDET is LOW
5
DLB
Asynchronous TTL
input
Diagnostic Loop Back Selector.
When DLB is LOW, LOOP Mode is OFF. Output of the transmitter shifter is
routed to both OUTA± and OUTB± and the serial input selected by A/B is routed
to the receive PLL for data recovery.
When DLB is HIGH, Diagnostic Loopback is Enabled. Output of the transmitter
serial data is routed to the receive PLL for data recovery. Primarily used for
System Diagnostic test. The serial inputs are ignored and OUTA± and OUTB±
are both active.
1
TEST
Asynchronous TTL
input normally wired
HIGH
Test Mode Select.
Used to force the part into a diagnostic test mode used for factory ATE test. This
input must be tied HIGH during normal operation.
Power
80, 87, VDDA
88, 95,
96, 98
Document #: 38-02020 Rev. *C
Power for PECL-compatible I/O signals and internal circuits.
Page 11 of 46
CY7C9689A
Pin Descriptions (continued)
Pin
Name
I/O Characteristics
Signal Description
76, 79, VSSA
83, 84,
91, 92,
99
Ground for PECL-compatible I/O signals and internal circuits.
14, 17, VDD
35, 55,
62, 64
Power for TTL I/O signals and internal circuits.
4,11, VSS
13, 15,
26, 37,
38, 39,
52, 57,
63, 66
Ground for TTL I/O signals and internal circuits.
CY7C9689A HOTLink Operation
Overview
The CY7C9689A is designed to move parallel data across
both short and long distances with minimal overhead or host
system intervention. This is accomplished by converting the
parallel characters into a serial bit-stream, transmitting these
serial bits at high speed, and converting the received serial bits
back into the original parallel data format.
The CY7C9689A offers a large feature set, allowing it to be
used in a wide range of host systems. Some of the configuration options are
• AMD TAXIchip 4B/5B- and 5B/6B-compatible
encoder/decoder
• AMD TAXIchip-compatible serial link
• AMD TAXIchip parallel COMMAND and DATA I/O bus
architecture
• 8-bit or 10-bit character size
• User-definable data packet or frame structure
• Two-octave data rate range
• Asynchronous (FIFOed) or synchronous data interface
• Embedded or bypassable FIFO data storage
• Encoded or non-encoded
• Multi-PHY capability
This flexibility allows the CY7C9689A to meet the data
transport needs of almost any system.
Transmit Data Path
Transmit Data Interface/Transmit Data FIFO
The transmit data interface to the host system is configurable
as either an asynchronous buffered (FIFOed) parallel interface
or as a synchronous pipeline register. The bus itself can be
configured for operation with either 8-bit or 10-bit character
widths.
When configured for asynchronous operation (where the
host-bus interface clock operates asynchronous to the serial
character and bit stream clocks), the host interface becomes
that of a synchronous FIFO clocked by TXCLK. In this configuration an internal 256-character Transmit FIFO is enabled
that allows the host interface to be written at any rate from DC
to 50 MHz.
Document #: 38-02020 Rev. *C
When configured for synchronous operation, the transmit
interface is clocked by REFCLK and operates synchronous to
the internal character and bit-stream clocks. The input register
can be written at either 1/10 or 1/12 the serial bit rate. This
interface can be clocked at up to 40 MHz when configured for
8-bit data width, and up to 33 MHz when configured for 10-bit
data bus width. Actual clock rate depends on data rate as well
as RANGESEL and SPDSEL logic levels.
Both asynchronous and synchronous interface operations
support user control over the logical sense of the FIFO status
flags. Full and empty flags on both the transmitter and receiver
can be active HIGH or active LOW. This facilitates interfacing
with existing control logic or external FIFOs with minimal or no
external glue logic.
Encoder
Data from the host interface or Transmit FIFO is next passed
to an Encoder block. The CY7C9689A contains both 4B/5B
and 5B/6B encoders that are used to improve the serial
transport characteristics of the data. For those systems that
contain their own encoder or scrambler, this Encoder may be
bypassed.
Serializer/Line Driver
The data from the Encoder is passed to a Serializer. This
Serializer operates at 10 or 12 times the character rate. With
the internal FIFOs enabled, REFCLK can run at 1x, 2x, or 4x
the character rate. With the FIFOs bypassed, REFCLK can
operate at 1x or 2x the character rate. The serialized data is
output in NRZI format from two PECL-compatible differential
line drivers configured to drive transmission lines or optical
modules.
Receive Data Interface
Line Receiver/Deserializer/Framer
Serial data is received at one of two PECL-compatible differential line receivers. The data is passed to both a Clock and
Data Recovery PLL and to a Deserializer that converts NRZI
serial data into NRZ parallel characters. The Framer adjusts
the boundaries of these characters to match those of the
original transmitted characters.
Decoder
The parallel characters are passed through a pair of 5B/4B or
6B/5B decoders and returned to their original form. For
Page 12 of 46
CY7C9689A
systems that make use of external decoding or descrambling,
the decoder may be bypassed.
Receive Data Interface/Receive Data FIFO
Data from the decoder is passed either to a synchronous
Receive FIFO or is passed directly to the output register. The
output register can be configured for either 8-bit character or
10-bit character operation.
When configured for an asynchronous buffered (FIFOed)
interface, the data is passed through a 256-character Receive
FIFO that allows data to be read at any rate from DC to 50
MHz. When configured for synchronous operation (Receive
FIFO is bypassed) data is clocked out of the Receive Output
register at up to 20 MHz when configured for 8-bit characters,
or 16.67 MHz when configured for 10-bit characters. The
receive interface is also configurable for FIFO flags with either
HIGH or LOW status indication
Oscillator Speed Selection
The CY7C9689A is designed to operate over a two-octave
range of serial signaling rates, covering the 50- to 200-MBaud
range. To cover this wide range, the PLLs are configured into
various sub-regions using the SPDSEL and RANGESEL
inputs, and to a limited extent the BYTE8/10 input. These
inputs are used to configure the various prescalers and clock
dividers used with the transmit and receive PLLs.
made compatible with asynchronous or synchronous host
system buses. These buses can take the form of external
FIFOs, state machines, or other control structures. Data and
command present on the TXDATA[9:0] and TXSC/D inputs are
captured at the rising edge of the selected sample clock. The
transmit data bus bit-assignments vary depending on the data
encoding and bus-width selected. These bus bit-assignments
are shown in Table 1, and list the functional names of these
different signals. Note that the function of several of these
signals changes in different operating modes. The logical
sense of the enable and FIFO flag signals depends on the
intended interface convention and is set by the EXTFIFO pin.
The transmit interface supports both synchronous and
asynchronous clocking modes, each supporting both UTOPIA
and Cascade timing models. The selection of the specific
clocking mode is determined by the RANGESEL and SPDSEL
inputs and the FIFO Bypass (FIFOBYP) signal.
TXDATA[7:0]
REFCLK
TXCMD[3:0]
TXEN
TXCLK
TXSC/D
CE
12
Transmit Input Register
CY7C9689A TAXI HOTLink Transceiver
Block Diagram Description
14
Transmit Input/Output Register
The CY7C9689A provides a synchronous interface for data
and command inputs, instead of the TAXI’s asynchronous
strobed interface. The Transmit Input Register, shown in
Figure 2, captures the data and command to be processed by
the HOTLink Transmitter, and allows the input timing to be
Table 1. Transmit Input Bus Signal Map
TXDATA Bus Input Bit
TXSC/D
TXDATA[0]
TXDATA[1]
TXDATA[2]
TXDATA[3]
TXDATA[4]
TXDATA[5]
TXDATA[6]
TXDATA[7]
TXDATA[8]/TXCMD[3]
TXDATA[9]/TXCMD[2]
TXCMD[1]
TXCMD[0]
Encoded 8-bit
Character Stream[2]
TXSC/D
TXDATA[0]
TXDATA[1]
TXDATA[2]
TXDATA[3]
TXDATA[4]
TXDATA[5]
TXDATA[6]
TXDATA[7]
TXCMD[3]
TXCMD[2]
TXCMD[1]
TXCMD[0]
To Encoder
Block
Transmit FIFO
Figure 2. Transmit Input Register
Transmit Encoder Mode[1]
Pre-encoded 10-bit
Encoded 10-bit
Character Stream
Character Stream[3]
TXSC/D
TXD[0][4]
TXDATA[0]
TXD[1]
TXDATA[1]
TXD[2]
TXDATA[2]
TXD[3]
TXDATA[3]
TXD[4]
TXDATA[4]
TXD[5]
TXDATA[5]
TXD[6]
TXDATA[6]
TXD[7]
TXDATA[7]
TXD[8]
TXDATA[8]
TXD[9]
TXDATA[9][3]
TXCMD[1]
TXCMD[0]
Pre-encoded 12-bit
Character Stream
TXD[0][5]
TXD[1]
TXD[2]
TXD[3]
TXD[4]
TXD[5]
TXD[6]
TXD[7]
TXD[8]
TXD[9]
TXD[10][5]
TXD[11]
Notes:
1. All open cells are ignored.
2. When ENCBYP is HIGH and BYTE8/10 is HIGH, transmitted bit order is the encoded form (MSB to LSB) of TXDATA[7,6,5,4] and TXDATA[3,2,1,0] or
TXCMD[3,2,1,0] as selected by TXSC/D.
3. When ENCBYP is HIGH and BYTE8/10 is LOW, transmitted bit order is the encoded form (MSB to LSB) of TXDATA[8,7,6,5,4] and TXDATA[9,3,2,1,0] or
TXCMD[1,0] as selected by TXSC/D.
4. When ENCBYP is LOW and BYTE8/10 is HIGH, the transmitted bit order is (LSB to MSB) TXD[0,1,2,3,4,5,6,7,8,9].
5. When ENCBYP is LOW and BYTE8/10 is LOW, the transmitted bit order is (LSB to MSB) TXD[0,1,2,3,4,5,6,7,8,9,11,10].
Document #: 38-02020 Rev. *C
Page 13 of 46
CY7C9689A
Synchronous Interface
Synchronous interface clocking operates the entire transmit
data path synchronous to REFCLK. It is enabled by
connecting FIFOBYP LOW to disable the internal FIFOs.
Asynchronous Interface
Asynchronous interface clocking controls the writing of host
bus data into the Transmit FIFO. It is enabled by setting
FIFOBYP HIGH to enable the internal FIFOs. In these configurations, all writes to the Transmit Input Register, and
associated transfers to the Transmit FIFO, are controlled by
TXCLK. The remainder of the transmit data path is clocked by
REFCLK or synthesized derivatives of REFCLK.
Shared Bus Timing Model
The Shared Bus Timing Model allows multiple CY7C9689A
transmitters to be accessed from a common host bus. It is
enabled by setting EXTFIFO LOW. In shared bus timing, the
TXEMPTY and TXFULL outputs and TXEN input are all active
LOW signals. If the CY7C9689A is addressed by asserting CE
LOW, it becomes “selected” when TXEN is asserted LOW.
Following selection, data or command is written into the
Transmit FIFO on every clock cycle where TXEN remains
LOW.
write is enabled (the device is selected and TXEN is sampled
asserted), data is captured in the transmit input register and
stored into the Transmit FIFO. All Transmit FIFO write operations are clocked by TXCLK.
The Transmit FIFO presents Full, Half-Full, and Empty FIFO
flags. These flags are provided synchronous to TXCLK. When
the Transmit FIFO is enabled, it allows operation with a
Moore-type external controlling state machine. When
configured for Cascade timing, the timing and active levels of
these signals are also designed to support direct expansion to
Cypress CY7C42x5 synchronous FIFOs.
Regardless of bus width (8- or 10-bit characters) the Transmit
FIFO can be clocked at any rate from DC to 50 MHz. This
gives the Transmit FIFO a maximum bandwidth of 50 million
characters per second. Since the serial outputs can only move
20 million characters per second at their fastest operating rate,
there is ample time to service multiple CY7C9689A HOTLinks
with a single controller.
The read port of the Transmit FIFO is connected to a logic
block that performs data formatting and validation. All data
read operations from the Transmit FIFO are controlled by a
Transmit Control State Machine that operates synchronous to
REFCLK.
Cascade Timing Model
Encoder Block
The Cascade timing model is a variation of the shared bus
timing model. Here the TXEMPTY and TXFULL outputs, and
TXEN input, are all active HIGH signals. Cascade timing
makes use of the same selection sequences as shared bus
timing, but write data accesses use a delayed write. This
delayed write is necessary to allow direct coupling to external
FIFOs, or to state machines that initiate a write operation one
clock cycle before the data is available on the bus.
The Encoder logic block performs two primary functions:
encoding the data for serial transmission and generating BIST
patterns to allow at-speed link and device testing.
Cascade timing is enabled by setting EXTFIFO HIGH.
When used for FIFO depth expansion, Cascade timing allows
the size of the internal Transmit FIFO to be expanded to an
almost unlimited depth. It allows a CY7C42x5 series
synchronous FIFO to be attached to the transmit interface
without any extra logic, as shown in Figure 3.
CY7C42x5 FIFO
FF*
FF*
WEN*
WEN*
D
D
TXCLK
CY7C9689A
EF*
BIST LFSR
The Encoder logic block operates on data stored in a register.
This register accepts information directly from the Transmit
FIFO, the Transmit Input Register or from the Transmit Control
State Machine when it inserts special characters into the data
stream.
This same register is converted into a Linear Feedback Shift
Register (LFSR) when the BIST pattern generator is enabled
(TXBISTEN is LOW). When enabled, this LFSR generates a
511-character sequence that includes all Data and Special
Character codes, including the explicit violation symbols. This
provides a predictable but pseudo-random sequence that can
be matched to an identical LFSR in the Receiver.
TXEN
Encoder
REN*
TXFULL
Q
TXDATA
TXSC/D
The data passed through the Transmit FIFO and pipeline
register, or as received directly from the Transmit Input
Register, is seldom in a form suitable for transmission across
a serial link. The characters must usually be processed or
transformed to guarantee:
•a minimum transition density (to allow the serial receiver PLL
to extract a clock from the data stream)
•some way to allow the remote receiver to determine the
correct character boundaries (framing).
The CY7C9689A contains an integrated 4B/5B encoder that
accepts 8-bit data characters and converts these into 10-bit
transmission characters that have been optimized for
transport on serial communications links. This 4B/5B encoding
scheme is compliant with the ANSI X3T9.5 (FDDI)
committee’s 4B/5B code. The CY7C9689A also contains a
5B/6B encoder that accepts 10-bit data characters and
converts these into 12-bit transmission characters.
WCLK RCLK
TXCLK
“1”
EXTFIFO
Figure 3. External FIFO Depth Expansion of the
CY7C9689A Transmit Data Path
Transmit FIFO
The Transmit FIFO is used to buffer data and command
captured in the input register for later processing and transmission. This FIFO is sized to hold 256 14-bit characters.
When the Transmit FIFO is enabled, and a Transmit FIFO
Document #: 38-02020 Rev. *C
Page 14 of 46
CY7C9689A
The 4B/5B, 5B/6B encoder can be bypassed for those
systems that operate with external 4B/5B or 5B/6B encoders
or use alternate forms of encoding or scrambling to ensure
good transmission characteristics. The complete encoding
tables are listed in Table 7 and Table 8.
OUTA± receives its data directly from the transmit shifter, while
OUTB± receives its data from the Routing Matrix. These two
outputs (OUTA± and OUTB±) are capable of direct connection
to +5V optical modules, and can also directly drive DC- or
AC-coupled transmission lines.
When the Encoder is enabled, the transmit data characters (as
passed through the Transmit FIFO and pipeline register) are
converted to either a 10-bit or 12-bit Data symbol or a 10-bit or 12-bit
Command Character, depending upon the state of the TXSC/D
input. If TXSC/D is HIGH, the data on the command inputs are
encoded into Command Character as shown in Table 8. If TXSC/D
is LOW, the data inputs are encoded using the Data Character
encoding in Table 7.
The PECL-compatible Output Drivers can be viewed as
programmable current sources. The output voltage is determined by the output current and the load impedance ZLOAD.
The desired output voltage swing is therefore controlled by the
current-set resistor RCURSET associated with that driver.
Different RCURSET values are required for different line
impedance/amplitude combinations. The output swing is
designed to center around VDD–1.33V. Each output must be
externally biased to VDD–1.33V.
The 4B/5B, 5B/6B coding function of the Encoder can be
bypassed for systems that include an external coder or
scrambler function as part of the controller or host system. This
is performed by setting ENCBYP LOW. With the encoder
bypassed, each 10-bit or 12-bit character (as captured in the
Transmit Input Register) is passed directly to the Transmit
Shifter (or Transmit FIFO) without modification.
Transmit Shifter
The Transmit Shifter accepts 10-bit (BYTE8/10 = HIGH) or
12-bit (BYTE8/10 = LOW) parallel data from the Encoder block
once each character time, and shifts it out the serial interface
output buffers using a PLL-multiplied bit-clock with NRZI
encoding. This bit-clock runs at 2.5, 5, or 10 times the REFCLK
rate (3, 6, or 12 times when BYTE8/10 is LOW) as selected by
RANGESEL and SPDSEL (see Table 3). Timing for the
parallel transfer is controlled by the counter and dividers in the
Clock Multiplier PLL and is not affected by signal levels or
timing at the input pins. Bits in each character are shifted out
LSB first.
Routing Matrix
The Routing Matrix is a precision multiplexor that allows local
diagnostic loopback. The signal routing for the transmit serial
outputs is controlled by the DLB input as listed in Table 2.
Table 2. Transmit Data Routing Matrix
DLB[0]
Data Connections
OUTA
A/B
OUTB
INB
RECEIVE
PLL
INA
1
TRANSMIT
SHIFTER
When specified into a single-ended load (one of the outputs
switching into a load), the single output will both source and
sink current as it changes between its HIGH and LOW levels.
The voltage difference between this HIGH level and LOW level
determine the peak-to-peak signal-swing of the output. This
amplitude relationship is controlled by the load impedance on
the driver, and by the resistance of the RCURSET resistor for
that driver, as listed in Eq. 1
180 × Z LOAD
R CURSET = --------------------------------V OPP
Eq. 1
In Eq. 1, VOPP is the difference in voltage levels at one output
of the differential driver when that output is driving HIGH and
LOW, ZLOAD is that load seen by the one output when it is
sourcing and sinking current. With a known load impedance
and a desired signal swing, it is possible to calculate the value
of the associated CURSETA or CURSETB resistor that sets
this current.
Unused differential output drivers should be left open, and can
reduce their power dissipation by connecting their respective
CURSETx input to VDD.
Transmit PLL Clock Multiplier
0
TRANSMIT
SHIFTER
This differential output-swing can be specified two ways: either
as a peak-to-peak voltage into a single-end load, or as an
absolute differential voltage into a differential load.
OUTA
A/B
OUTB
The Transmit PLL Clock Multiplier accepts an external clock at
the REFCLK input, and multiples that clock by 2.5, 5, or 10 (3,
6, or 12 when BYTE8/10 is LOW and the encoder is disabled)
to generate a bit-rate clock for use by the transmit shifter. It
also provides a character-rate clock used by the Transmit
Controller state machine.
The clock multiplier PLL can accept a REFCLK input between
8 MHz and 40 MHz, however, this clock range is limited by the
operation mode of the CY7C9689A as selected by the
SPDSEL and RANGESEL inputs, and to a limited extent, by
the BYTE8/10 and FIFOBYP signals. The operating serial
signalling rate and allowable range of REFCLK frequencies is
listed in Table 3.
INB
RECEIVE
PLL
INA
Serial Line Drivers
Transmit Control State Machine
The Transmit Control State Machine responds to multiple
inputs to control the data stream passed to the encoder. It
operates in response to:
The serial interface PECL Output Drivers (ECL referenced to
+5V) are the transmission line drivers for the serial media.
Document #: 38-02020 Rev. *C
Page 15 of 46
CY7C9689A
Table 3. Speed Select and Range Select Settings
REFCLK[7]
Frequency
(MHz)
SPDSEL
RANGESEL
Serial
Data Rate
(MBaud)
LOW
LOW
50–100
10–20
LOW
HIGH[6]
50–100
20–40
HIGH
LOW
100–200
10–20
HIGH
HIGH
100–200
20–40
•the state of the FIFOBYP input
•the presence of data in the Transmit FIFO
•the contents of the Transmit FIFO
•the state of the transmitter BIST enable (TXBISTEN)
•the state of external halt signal (TXHALT).
These signals are used by the Transmit Control State Machine
to control the data formatter, read access to the Transmit FIFO
and BIST. They determine the content of the characters
passed to the Encoder and Transmit Shifter.
When the Transmit FIFO is bypassed, the Transmit Control
State Machine operates synchronous to REFCLK. In this
mode, data from the TXDATA bus is passed directly from the
Input Register to the Pipeline Register. If no data is enabled
into the Input register (TXEN is deasserted or TXFULL is
asserted) then the Transmit Control State Machine presents a
JK or LM (when BYTE8/10 = LOW) Command Character code
to the Encoder to maintain link synchronization.
If both the Encoder and Transmit FIFO are bypassed and no
data is enabled into the Input Register, the Transmit Control
State Machine injects JK or LM (when BYTE8/10 = LOW) into
the Serial Shifter Register at this time slot. This also occurs if
the Encoder is bypassed, the Transmit FIFO is enabled, and
the Transmit FIFO is empty.
External Control of Data Flow
The Transmit Control State Machine supports halting of data
transmission by the TXHALT input. This control signal input is
only interpreted when the Transmit FIFO is enabled. TXHALT
is brought directly to the state machine without going through
the Transmit FIFO.
The assertion of TXHALT causes character processing to stop
at the next FIFO character location. No additional data is read
from the Transmit FIFO until TXHALT is deasserted.
TXHALT may be used to prevent a remote FIFO overflow,
which would result in lost data. This back-pressure mechanism
can significantly improve data integrity in systems that cannot
guarantee the full bandwidth of the host system at all times.
Serial Line Receivers
Two differential line receivers, INA± and INB±, are available for
accepting serial data streams, with the active input selected
using the A/B input. The DLB input allow the transmit Serializer
output to be selected as a third input serial stream, but this path is
generally used only for local diagnostic loopback purposes. The
serial line receiver inputs are all differential, and will accommodate
wire interconnect with filtering losses or transmission line attenuation greater than 9 dB (VDIF > 200 mV, or 400 mV peak-to-peak
differential) or can be directly connected to +5V fiber-optic interface
modules (any ECL logic family, not limited to ECL 100K). The
common-mode tolerance of these line receivers accommodates a
wide range of signal termination voltages.
As can be seen in Table 2, these inputs are configured to allow
single-pin control for most applications. For those systems
requiring selection of only INA± or INB±, the DLB signals can be
tied LOW, and the A/B selection can be performed using only
A/B. For those systems requiring only a single input and a local
loopback, the A/B can be tied HIGH or LOW, and DLB can be
used for loopback control.
Signal Detect
The selected Line Receiver (that routed to the clock and data
recovery PLL) is simultaneously monitored for:
•analog amplitude (> 400 mV pk-pk)
•transition density
•received data stream outside normal frequency range
(±400 ppm)
•carrier detected.
All of these conditions must be valid for the Signal Detect block
to indicate a valid signal is present. This status is presented on
the LFI (Link Fault Indicator) output, which changes
synchronous to RXCLK. While link status is monitored internally at all times, it is necessary to have transitions on RXCLK
to allow this signal to change externally.
Clock/Data Recovery
The extraction of a bit-rate clock and recovery of data bits from
the received serial stream is performed within the Clock/Data
Recovery (CDR) block. The clock extraction function is
performed by a high-performance embedded PLL that tracks
the frequency of the incoming bit stream and aligns the phase
of its internal bit-rate clock to the transitions in the serial data
stream.
The CDR makes use of the clock present at the REFCLK input.
It is used to ensure that the VCO (within the CDR) is operating
at the correct frequency (rather than some harmonic of the bit
rate), to improve PLL acquisition time, and to limit unlocked
frequency excursions of the CDR VCO when no data is
present at the serial inputs.
Regardless of the type of signal present, the CDR will attempt
to recover a data stream from it. If the frequency of the
recovered data stream is outside the limits for the range
controls, the CDR PLL will track REFCLK instead of the data
stream. When the frequency of the selected data stream
returns to a valid frequency, the CDR PLL is allowed to track
the received data stream. The frequency of REFCLK is
required to be within ±400 ppm of the frequency of the clock
that drives the REFCLK signal at the remote transmitter to
ensure a lock to the incoming data stream.
Notes:
6. When SPDSEL is LOW and the FIFOs are bypassed (FIFOBYP is LOW), the RANGESEL input is ignored and is internally mapped to the LOW setting.
7. When configured for 12-bit preencoded data (BYTE8/10 and ENCBYP are both LOW) the allowable REFCLK ranges are 8.33 to 16.67 MHz and 16.67 to
33.33 MHz.
Document #: 38-02020 Rev. *C
Page 16 of 46
CY7C9689A
For systems using multiple or redundant connections, the LFI
output can be used to select an alternate data stream. When
an LFI indication is detected, external logic can toggle
selection of the INA± and INB± inputs through the A/B input.
When a port switch takes place, it is necessary for the PLL to
reacquire the new serial stream and frame to the incoming
characters.
Clock Divider
This block contains the clock division logic, used to transfer the
data from the Deserializer/Framer to the Decoder once every
character (once every ten or twelve bits) clock. This counter is
free running and generates outputs at the bit-rate divided by
10 (12 when the BYTE8/10 is LOW). When the Receive FIFO
is bypassed, one of these generated clocks is driven out the
RXCLK pin.
Deserializer/Framer
The CDR circuit extracts bits from the serial data stream and
clocks these bits into the Shifter/Framer at the bit-clock rate.
When enabled, the Framer examines the data stream looking
for JK or LM (when BYTE8/10 is LOW) characters at all
possible bit positions. The location of this character in the data
stream is used to determine the character boundaries of all
following characters.
The framer operates in two different modes, as selected by the
RFEN input. When RFEN is asserted (HIGH), the framer is
allowed to reset the internal character boundaries on any
detected JK or LM (when BYTE8/10 is LOW) character.
If RFEN is LOW, the framer is disabled and no changes are
made to character boundaries.
The framer in the CY7C9689A operates by shifting the internal
character position to align with the character clock. This
ensures that the recovered clock does not contain any significant phase changes/hops during normal operation or framing,
and allows the recovered clock to be replicated and distributed
to other circuits using PLL-based logic elements.
Decoder Block
The decoder logic block performs two primary functions:
decoding the received transmission characters back into Data
and Command Character codes, and comparing generated
BIST patterns with received characters to permit at-speed link
and device testing.
5B/4B, 6B/5B Decoder
The framed parallel output of the Deserializer is passed to the
5B/4B, 6B/5B Decoder. If the Decoder is enabled, it is transformed from a 10-bit or 12-bit transmission character back to
the original Data and Command Character codes. This block
uses the standard decoder patterns in Table 7 and Table 8 of
this data sheet. Data Patterns on the data bus are indicated by
a LOW on RXSC/D, and Command Character codes on the
command bus are indicated by a HIGH. Invalid patterns or disparity
errors are signaled as errors by a HIGH on VLTN.
If the Decoder is bypassed and BYTE8/10 is HIGH, the ten
(10) data bits of each transmission character are passed
unchanged from the framer to the Pipeline Register.
When the Decoder is bypassed and BYTE8/10 is LOW, the
twelve (12) data bits of each transmission character are
passed unchanged from the framer to the Pipeline Register.
Document #: 38-02020 Rev. *C
BIST LFSR
The output register of the Decoder block is normally used to
accumulate received characters for delivery to the Receive
Formatter block. When configured for BIST mode (RXBISTEN
is LOW), this register becomes a signature pattern generator
and checker by logically converting to a Linear Feedback Shift
Register (LFSR). When enabled, this LFSR generates a
511-character sequence that includes all Data and Command
Character codes, including the explicit violation symbols. This
provides a predictable but pseudo-random sequence that can
be matched to an identical LFSR in the Transmitter. When
synchronized with the received data stream, it checks each
character in the Decoder with each character generated by the
LFSR and indicates compare errors at the VLTN output of the
Receive Output Register.
The LFSR is initialized by the BIST hardware to the BIST loop
start code of HEX data 00 (00 is sent only once per BIST loop).
Once the start of the BIST loop has been detected by the
receiver, RXRVS is asserted for pattern mismatches between
the received characters and the internally generated character
sequence. Code rule violations or running disparity errors that
occur as part of the BIST loop do not cause an error indication.
RXFULL pulses asserted for one RXCLK cycle per BIST loop and
can be used to check test pattern progress.
The specific patterns checked by the receiver are described in
Table 4.
If a large number of errors are detected, the receive BIST state
machine aborts the compare operations and resets the LFSR
to the D0.0 state to look for the start of the BIST sequence
again.
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 controls the various discard
policies and error control within the receiver, and operates in
response to:
•the received character stream
•the room for additional data in the Receive FIFO
•the state of the receiver BIST enable (RXBISTEN)
•the state of FIFOBYP.
These signals and conditions are used by the Receive Control
State Machine to control the Receive Formatter, write access
to the Receive FIFO, 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.
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.
Page 17 of 46
CY7C9689A
able 4. CY7C9689A TAXI HOTLink BIST Sequence
D.00
C.JK
C.TR
D.89
C.JK
C.IH
C.SR
D.42
C.IH
C.QI
C.SS
C.HI
C.SR
D.EE
C.QQ
D.94
C.SS
C.RR
D.F8
C.TT
C.QQ
D.B3
C.TS
C.TR
D.FB
D.55
C.QH
C.QI
D.77
D.2C
D.D2
D.EB
D.3D
C.JK
C.RR
D.73
D.1E
C.RS
D.BC
D.35
C.HH
D.C5
C.TT
D.1C
D.8F
D.68
C.QH
C.JK
D.4B
C.II
D.D7
C.RS
D.23
C.RS
D.6D
D.CF
D.11
D.C0
D.3A
D.6B
D.04
C.TS
C.HH
D.33
D.15
D.A8
D.99
D.D1
D.0C
C.TT
D.46
D.64
C.JK
C.QH
C.HI
C.II
C.RS
D.D4
D.96
C.IH
D.CD
C.TS
C.HQ
C.QI
D.6A
C.TR
D.AE
D.E4
C.HI
C.QI
C.HQ
C.RR
D.91
D.E3
D.A3
C.TR
D.44
D.71
D.51
C.QI
C.II
D.34
D.24
D.E0
C.IH
C.JK
C.JK
C.TS
C.QI
C.IH
C.IH
C.TR
D.E6
C.QI
C.QI
C.SR
C.RR
D.ED
D.EC
C.SS
D.B2
D.7A
C.TS
C.SS
C.HQ
C.HI
C.QH
C.SS
C.SS
C.QQ
D.50
D.DD
C.QQ
D.FC
C.II
D.6E
D.F0
C.TS
C.IH
C.HI
C.TS
C.QH
C.SR
D.93
C.TR
D.D3
C.QQ
D.45
C.SR
D.65
D.FD
D.28
C.QQ
D.38
D.7E
C.JK
D.F4
C.JK
C.HI
C.RS
C.TS
C.RS
D.9B
D.C4
C.TR
D.C6
D.47
C.TS
C.QI
C.RR
D.29
C.TR
D.E1
D.B6
D.12
C.QI
D.70
C.HQ
C.HH
D.E2
C.II
D.AA
D.8C
C.RR
C.IH
C.HQ
C.TT
D.B0
C.SR
D.A1
C.QH
C.TT
C.TR
D.17
D.BD
C.HI
C.SR
D.0D
D.5E
D.92
C.QQ
D.0A
C.HI
C.HQ
D.F6
C.HH
D.9F
D.AC
C.RR
D.85
D.4F
C.TT
D.BA
D.48
D.2B
C.QH
C.HQ
C.II
D.13
D.D5
D.A9
C.RS
D.05
D.6C
D.52
D.C8
D.08
C.II
C.HI
C.TS
C.JK
C.RS
D.9C
C.QH
C.RS
D.C1
C.TT
D.D8
D.CC
D.60
C.QH
C.TS
C.TS
C.II
D.DF
C.QH
C.QH
C.IH
D.6F
D.DA
D.D9
C.SR
D.3B
C.RR
D.66
C.SS
C.SS
C.TR
D.02
C.HH
C.SS
C.QI
C.HH
D.8A
C.QQ
D.E9
D.84
C.HQ
D.F1
D.72
C.TT
D.A5
D.74
C.HI
C.TR
D.58
C.II
D.98
C.QI
C.II
C.IH
C.TT
D.EA
C.RS
C.QI
C.QH
C.RR
D.CA
D.E5
D.DE
D.B1
C.RR
D.78
C.RR
D.54
D.B5
C.II
D.BF
C.II
D.5C
C.RS
D.5F
C.IH
C.II
D.C2
D.2F
C.QI
C.RS
C.RR
D.1B
D.E7
D.CB
D.B4
D.07
D.79
D.63
C.TT
D.09
D.36
D.31
D.14
C.TR
D.4D
C.HQ
C.JK
C.SR
D.2A
D.AF
C.IH
C.SS
C.HH
D.5B
C.QI
C.QQ
D.81
D.27
D.EF
D.F9
D.40
D.19
D.7B
D.76
C.II
D.06
D.37
C.HI
C.IH
C.HH
D.1D
D.9A
C.SR
D.86
D.0E
C.HQ
C.SS
C.HQ
C.HH
D.AD
C.QQ
D.A6
D.87
D.5A
D.FA
C.HQ
D.49
C.HI
C.RR
D.A2
D.22
D.9D
D.B9
C.HQ
C.HH
D.4E
D.56
D.AO
D.80
C.HI
C.HI
C.TT
C.TT
D.97
D.9E
C.TR
C.SR
D.18
C.SS
C.QH
C.SS
C.JK
C.QQ
D.DB
C.SS
C.RS
D.F3
D.67
C.QQ
D.CE
D.75
D.39
D.F2
C.RR
D.3C
D.16
C.RR
D.B7
C.JK
C.HH
D.B8
D.5D
C.RS
D.8E
C.TT
D.2E
D.C7
C.HQ
C.QH
C.HH
D.69
D.A7
D.D6
D.83
D.32
D.59
C.RR
D.41
C.HH
D.26
D.BE
D.20
D.88
C.HH
C.HQ
C.JK
C.TT
D.82
D.AB
C.IH
C.QH
C.HQ
D.53
C.SR
D.DC
D.A4
D.25
C.SS
C.TS
C.TT
C.TR
D.30
D.4C
D.43
C.QI
C.JK
C.II
D.21
D.E8
C.IH
C.RS
D.10
C.TS
C.SR
D.C9
C.JK
C.QH
C.QQ
D.62
C.IH
D.D0
D.FE
C.HI
C.SR
C.TS
C.RR
D.90
C.QQ
C.TR
D.BB
C.TT
D.FF
C.SR
D.57
C.TR
D.7F
C.QQ
D.2D
C.SR
D.3F
D.F5
D.1A
C.QQ
D.1F
D.7C
C.HH
D.F7
D.0F
C.II
D.8D
D.7D
D.0B
C.RS
D.4A
D.3E
D.03
D.C3
C.HI
C.HH
D.01
D.61
D.95
D.8B
GOTO
Start
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 5.
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.
Document #: 38-02020 Rev. *C
Table 5. Receiver Discard Policies
Policy #
Policy Description
0 (00)
Keep all received characters
1 (01)
Process Commands, discard all but the last JK or
LM SYNC character
2 (1X)
Process Commands, discard all C5.0 characters
Page 18 of 46
CY7C9689A
In discard policy 1, the JK or LM SYNC 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 JK or LM 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 the last
SYNC character which can be used as a delimiter.
CY7C42x5 FIFO
EF*
REN*
Q
RXEN
FF*
EF*
REN*
CY7C9689A
RXEMPTY
WEN*
Q
RXDATA
RXSC/D
D
Policy 2 is identical to policy 1 except that all C5.0 characters
are removed from the data stream.
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, the RXEMPTY flag indicates an
empty condition for all but the last JK or LM character before
any other character is presented. In discard policy 2, the
RXEMPTY flag indicates an empty condition for all JK or LM
SYNC 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.
This FIFO is sized to hold 256 14-bit characters. When the
FIFO is enabled, it is written to by the Receive Control State
Machine. When data is present in the Receive FIFO (as
indicated by the RXFULL, RXHALF, and RXEMPTY Receive
FIFO status flags), it can be read from the Output Register by
asserting CE and RXEN.
The read port on the Receive FIFO may be configured for the
same two timing models as the transmit interface: UTOPIA
and Cascade. Both are forms of a FIFO interface. The UTOPIA
timing model has active LOW RXEMPTY and RXFULL status
flags, and an active LOW RXEN enable. When configured for
Cascade operation, these same signals are all active HIGH.
Either timing model supports connection to various host bus
interfaces, state machines, or external FIFOs for depth
expansion (see Figure 4).
The Receive FIFO presents Full, Half-Full, and Empty FIFO
status flags. These flags are provided synchronous to RXCLK
to allow operation with a Moore-type external controlling state
machine. When configured with the Receive FIFO enabled,
RXCLK is an input. When the Receive FIFO is bypassed
(FIFOBYP is LOW), RXCLK is an output operating at the
received character rate.
Document #: 38-02020 Rev. *C
RXCLK
RCLK WCLK
RXCLK
“1”
EXTFIFO
Figure 4. External FIFO Depth Expansion of the
CY7C9689A Receive Data Path
Receive Input Register
The input register is clocked by the rising edge of RXCLK. It
samples numerous signals that control the reading of the
Receive FIFO and operation of the Receive Control State
Machine.
Receive Output Register
The Receive Output Register changes in response to the
rising edge of RXCLK. The Receive FIFO status flag outputs
of this register are placed in a High-Z state when the
CY7C9689A is not addressed (CE is sampled HIGH). The
RXDATA bus output drivers are enabled when the device is
selected by RXEN being asserted in the RXCLK cycle immediately following that in which the device was addressed (CE is
sampled LOW), and RXEN being sampled by RXCLK. This
initiates a Receive FIFO read cycle.
Just as with the TXDATA bus on the Transmit Input Register,
the receive outputs are also mapped by the specific decoding
and bus-width selected by the ENCBYP, BYTE8/10 and
FIFOBYP inputs. These assignments are shown in Table 6.
If the Receive FIFO and Decoder are bypassed, all received
characters are passed directly to the Receive Output Register.
If framing is enabled, and JK or LM sync characters have been
detected meeting the present framing requirements, the
output characters will appear on proper character boundaries.
If framing is disabled (RFEN is LOW) or sync characters have
not been detected in the data stream, the received characters
may not be output on their proper 10-bit boundaries. In this
mode, some form of external framing and decoding/descrambling must be used to recover the original source data.
Page 19 of 46
CY7C9689A
Table 6. Receiver Output Bus Signal Map
Receiver Decoder Mode[1]
RXDATA Bus Output Bit
Encoded 8-bit
Character Stream[8]
RXSC/D
RXSC/D
Pre-encoded 10-bit
Character Stream
Encoded 10-bit
Character Stream[9]
Pre-encoded 12-bit
Character Stream
RXSC/D
RXDATA[0]
RXD[0][10, 12]
RXD[1]
RXDATA[1]
RXD[1]
RXDATA[2]
RXD[2]
RXDATA[2]
RXD[2]
RXDATA[3]
RXD[3]
RXDATA[3]
RXD[3]
RXDATA[4]
RXDATA[4]
RXD[4]
RXDATA[4]
RXD[4]
RXDATA[5]
RXDATA[5]
RXD[5]
RXDATA[5]
RXD[5]
RXDATA[6]
RXDATA[6]
RXD[6]
RXDATA[6]
RXD[6]
RXDATA[7]
RXDATA[7]
RXD[7]
RXDATA[7]
RXD[7]
RXDATA[8]/RXCMD[3]
RXCMD[3]
RXD[8]
RXDATA[8]
RXD[8]
RXDATA[0]
RXDATA[0]
RXDATA[1]
RXDATA[1]
RXDATA[2]
RXDATA[3]
RXD[0]
[10, 11]
RXD[9]
[9]
RXDATA[9]
RXD[9]
RXDATA[9]/RXCMD[2]
RXCMD[2]
RXCMD[1]
RXCMD[1]
RXCMD[1]
RXD[10][12]
RXCMD[0]
RXCMD[0]
RXCMD[0]
RXD[11]
VLTN
VLTN
VLTN
Notes:
8. When BYTE8/10 is HIGH, received bit order is decoded form the serial stream and presented (MSB to LSB) at RXDATA[7,6,5,4] and RXDATA[3,2,1,0] or
RXCMD[3,2,1,0] as indicated by RXSC/D.
9. When BYTE8/10 is LOW, received bit order is decoded form the serial stream and presented (MSB to LSB) at RXDATA[8,7,6,5,4] and RXDATA[9,3,2,1,0]
or RXCMD[1,0] as indicated by RXSC/D.
10. First bit shifted into the receiver.
11. When ENCBYP is LOW and BYTE8/10 is HIGH, the received bit order is (LSB to MSB) RXD[0,1,2,3,4,5,6,7,8,9].
12. When ENCBYP is LOW and BYTE8/10 is LOW, the received bit order is (LSB to MSB) RXD[0,1,2,3,4,5,6,7,8,9,11,10].
Document #: 38-02020 Rev. *C
Page 20 of 46
CY7C9689A
DC Input Voltage ................................... –0.5V to VDD + 0.5V
Maximum Ratings
(Above which the useful life may be impaired. For user guidelines, not tested.)
Storage Temperature .................................–65°C to +150°C
Ambient Temperature with (Power Applied) –55°C to +125°C
Supply Voltage to Ground Potential ............... –0.5V to +6.5V
DC Voltage Applied to Outputs ..............–0.5V to VDD + 0.5V
Output Current into TTL Outputs (LOW) ......................30 mA
Static Discharge Voltage........................................... > 2001V
(per MIL-STD-883, Method 3015)
Latch-up Current..................................................... > 200 mA
Operating Range
Range
Commercial
Industrial
Ambient Temperature
0°C to +70°C
–40°C to +85°C
VDD
5.0V ± 10%
5.0V ± 10%
CY7C9689A DC Electrical Characteristics Over the Operating Range
Parameter
Description
Test Conditions
TTL Outputs
Output HIGH Voltage
IOH = −2 mA, VDD = Min.
VOHT
Output LOW Voltage
IOL = 8 mA, VDD = Min.
VOLT
IOST
Output Short Circuit Current
VOUT = 0V[13]
High-Z Output Leakage Current
IOZL
TTL Inputs
Input HIGH Voltage
VIHT
Input LOW Voltage
VILT
Input HIGH Current
VIN = VDD
IIHT
IILT
Input LOW Current
VIN = 0.0V
Input HIGH Current with Internal Pull-down
VIN = VCC
IILPDT
Input LOW Current with Internal Pull-up
VIN = 0.0V
IILPUT
Transmitter PECL-Compatible Output Pins: OUTA+, OUTA−, OUTB+, OUTB−
Output HIGH Voltage (VDD referenced)
Load = 50Ω to VDD − 1.33V;
VOHE
RCURSET = 10k
Output LOW Voltage (VDD referenced)
Load = 50Ω to VDD − 1.33V;
VOLE
RCURSET = 10k
VODIF
Output Differential Voltage |(OUT+) − (OUT−)| Load = 50Ω to VDD − 1.33V;
RCURSET = 10k
Receiver Single-ended PECL-Compatible Input Pin: CARDET
Input HIGH Voltage (VDD referenced)
VIHE
Input LOW Voltage (VDD referenced)
VILE
Input HIGH Current
VIN = VIHE(min.)
IIHE
Input LOW Current
VIN = VILE(max.)
IILE
Receiver Differential Line Receiver Input Pins: INA+, INA−, INB+, INB−
Input Differential Voltage |(IN+) − (IN−)|
VDIFF
Highest Input HIGH Voltage
VIHH
Lowest Input LOW Voltage
VILL
Input HIGH Current
VIN = VIHH Max.
IIHH
IILL[14]
Input LOW Current
VIN = VILL Min.
Miscellaneous
Power Supply Current
Freq. = Max.
Commercial
IDD[15]
Min.
Max.
Unit
0.4
−80
20
V
V
mA
mA
2.4
–30
–20
2.0
–0.5
VCC
0.8
±40
−40
+300
V
V
µA
µA
µA
µA
–300
VDD − 1.03 VDD − 0.83
V
VDD − 2.0
VDD − 1.62
V
600
1100
mV
VDD − 1.165
VDD
V
2.5
VDD − 1.475 V
+40
µA
–40
µA
200
2500
VDD
2.5
750
−200
Typ.
170
Max.
250
mV
V
V
µA
µA
mA
Capacitance[16]
Parameter
CINTTL
CINPECL
Description
TTL Input Capacitance
PECL input Capacitance
Test Conditions
TA = 25°C, f0 = 1 MHz, VDD = 5.0V
TA = 25°C, f0 = 1 MHz, VDD = 5.0V
Max.
7
4
Unit
pF
pF
Notes:
13. Tested one output at a time, output shorted for less than one second, less than 10% duty cycle.
14. To guarantee positive currents for all PECL voltages, an external pull-down resistor must be present.
15. Maximum ICC is measured with VDD = MAX, RFEN = LOW, and outputs unloaded. Typical IDD is measured with VDD = 5.0V, TA = 25°C, RFEN = LOW, and
outputs unloaded.
16. Tested initially and after any design or process changes that may affect these parameters, but not 100% tested.
Document #: 38-02020 Rev. *C
Page 21 of 46
CY7C9689A
AC Test Loads and Waveforms
5.0V
OUTPUT
R1=500Ω
R2=333Ω
CL ≤ 10 pF
(Includes fixture and
probe capacitance)
R1
VDD – 1.3
CL
CL
R2
(a) TTL AC Test Load
Vth=1.5V
0.0V
[17]
3.0V
3.0V
RL
(b) PECL AC Test Load
2.0V
0.8V
0.8V
80%
Vth=1.5V
VILE
< 1 ns
< 1 ns
[17]
VIHE
VIHE
2.0V
RL =50 Ω
CL < 5 pF
(Includes fixture and
probe capacitance)
80%
20%
20%
VILE
≤ 250 ps
(c) TTL Input Test Waveform
≤ 250 ps
(d) PECL Input Test Waveform
CY7C9689A Transmitter TTL Switching Characteristics, FIFO Enabled Over the Operating Range
Parameter
Description
Min.
Max.
Unit
50
MHz
fTS
TXCLK Clock Cycle Frequency With Transmit FIFO Enabled
tTXCLK
TXCLK Period
20
ns
tTXCPWH
TXCLK HIGH Time
6.5
ns
tTXCPWL
TXCLK LOW Time
6.5
tTXCLKR[16]
TXCLK Rise Time[18]
0.7
5
ns
tTXCLKF[16]
TXCLK Fall Time[18]
0.7
5
ns
tTXA
Flag Access Time From TXCLK↑ to Output
2
15
ns
tTXDS
Transmit Data Set-up Time to TXCLK↑
4
ns
tTXDH
Transmit Data Hold Time from TXCLK↑
1
ns
tTXENS
Transmit Enable Set-up Time to TXCLK↑
4
ns
tTXENH
Transmit Enable Hold Time from TXCLK↑
1
ns
ns
tTXRSS
Transmit FIFO Reset (TXRST) Set-up Time to TXCLK↑
4
ns
tTXRSH
Transmit FIFO Reset (TXRST Hold Time from TXCLK↑
1
ns
tTXCES
Transmit Chip Enable (CE) Set-up Time to TXCLK↑
4
ns
tTXCEH
Transmit Chip Enable (CE) Hold Time from TXCLK↑
1
ns
tTXZA
Sample of CE LOW by TXCLK↑, Output High-Z to Active HIGH or LOW
tTXOE
Sample of CE LOW by TXCLK↑ to Output Valid
1.5
20
ns
tTXAZ
Sample of CE HIGH by TXCLK↑ to Output in High-Z
1.5
20
ns
0
ns
Notes:
17. Cypress uses constant current (ATE) load configurations and forcing functions. This figure is for reference only.
18. Input/output rise and fall time is measured between 0.8V and 2.0V
Document #: 38-02020 Rev. *C
Page 22 of 46
CY7C9689A
CY7C9689A Receiver TTL Switching Characteristics, FIFO Enabled Over the Operating Range
Parameter
fRIS
tRXCLKIP
tRXCPWH
tRXCPWL
tRXCLKIR[16]
tRXCLKIF[16]
tRXENS
tRXENH
tRXRSS
tRXRSH
tRXCES
tRXCEH
tRXA
tRXZA
tRXOE
tRXZA
Description
RXCLK Clock Cycle Frequency With Receive FIFO Enabled
RXCLK Input Period
RXCLK Input HIGH Time
RXCLK Input LOW Time
RXCLK Input Rise Time[18]
RXCLK Input Fall Time[18]
Receive Enable Set-up Time to RXCLK↑
Receive Enable Hold Time from RXCLK↑
Receive FIFO Reset (RXRXT) Set-up Time to RXCLK↑
Receive FIFO Reset (RXRXT) Hold Time from RXCLK↑
Receive Chip Enable (CE) Set-up Time to RXCLK↑
Receive Chip Enable (CE) Hold Time from RXCLK↑
Flag and Data Access Time From RXCLK↑ to Output
Sample of CE LOW by RXCLK↑, Output High-Z to Active HIGH or LOW,[19]
or Sample of RXEN Asserted by RXCLK↑, Output High-Z to Active HIGH or LOW
Sample of CE LOW by RXCLK↑ to Output Valid,[19]
or Sample of RXEN Asserted by RXCLK↑ to RXDATA Outputs Valid
Sample of CE HIGH by RXCLK↑ to Output in High-Z,[19]
or Sample of RXEN Asserted by RXCLK↑ to RXDATA Outputs in High-Z
Min.
20
6.5
6.5
0.7
0.7
4
1
4
1
4
1
1.5
0
Max.
50
5
5
15
Unit
MHz
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
1.5
20
ns
1.5
20
ns
CY7C9689A Transmitter TTL Switching Characteristics, FIFO Bypassed Over the Operating Range
Parameter
tTRA
tREFDS
tREFDH
tREFENS
tREFENH
tREFCES
tREFCEH
tREFZA
tREFOE
tREFAZ
Description
Flag Access Time From REFCLK↑ to Output
Write Data Set-up Time to REFCLK↑
Write Data Hold Time from REFCLK↑
Transmit Enable Set-up Time to REFCLK↑
Transmit Enable Hold Time from REFCLK↑
Transmit Chip Enable (CE) Set-up Time to REFCLK↑
Transmit Chip Enable (CE) Hold Time from REFCLK↑
Sample of CE LOW by REFCLK↑, Output High-Z to Active HIGH or LOW
Sample of CE LOW by REFCLK↑ to Flag Output Valid
Sample of CE HIGH by REFCLK↑ to Flag Output High-Z
Min.
2
4
2
4
2
4
2
0
1.5
1.5
Max.
15
20
20
Unit
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
CY7C9689A Receiver TTL Switching Characteristics, FIFO Bypassed Over the Operating Range
Parameter
fROS[20]
tRXCLKOP
tRXCLKOD
tRXCLKOR[16]
tRXCLKOF[16]
tRXENS
Description
RXCLK Clock Output Frequency—100 to 200 MBaud 8-bit Operation
(SPDSEL is HIGH and BYTE8/10 is HIGH)
RXCLK Clock Output Frequency—50 to 100 MBaud 8-bit Operation
(SPDSEL is LOW and BYTE8/10 is HIGH)
RXCLK Clock Output Frequency—100 to 200 MBaud 10-bit Operation
(SPDSEL is HIGH and BYTE8/10 is LOW)
RXCLK Clock Output Frequency—50 to 100 MBaud 10-bit Operation
(SPDSEL is LOW and BYTE8/10 is LOW)
RXCLK Output Period
RXCLK Output Duty Cycle
RXCLK Output Rise Time[18]
RXCLK Output Fall Time[18]
Receive Enable Set-up Time to RXCLK↑
Min.
10
Max.
20
Unit
MHz
5
10
MHz
8.33
16.67
MHz
4.16
8.33
MHz
25
40
0.25
0.25
4
240
60
2
2
ns
%
ns
ns
ns
Note:
19. Parallel data output specifications are only valid if all outputs are loaded with similar DC and AC loads.
20. The period of tROS will match the period of the transmitter PLL reference (REFCLK) when receiving serial data. When data is interrupted, RXCLK may drift to REFCLK +0.2%.
Document #: 38-02020 Rev. *C
Page 23 of 46
CY7C9689A
CY7C9689A Receiver TTL Switching Characteristics, FIFO Bypassed Over the Operating Range (continued)
Parameter
tRXENH
tRXZA
tRXOE
tRXAZ
Description
Receive Enable Hold Time from RXCLK↑
Sample of CE LOW by RXCLK↑, Outputs High-Z to Active
Sample of RXEN Asserted by RXCLK↑ to RXDATA Outputs High-Z to Active
Sample of CE LOW by RXCLK↑ to Flag Output Valid
Sample of RXEN Asserted by RXCLK↑ to RXDATA Output Low-Z
Sample of CE HIGH by RXCLK↑ to Flag Output High-Z
Sample of RXEN Deasserted by RXCLK↑ to RXDATA Output High-Z
Min.
1
0
Max.
Unit
ns
ns
1.5
20
ns
1.5
20
ns
CY7C9689A REFCLK Input Switching Characteristics Over the Operating Range
Conditions
Parameter
fREF
Description
SPDSEL RANGESEL
BYTE8/10
Min.
Max.
Unit
REFCLK Clock Frequency—50 to 100 MBaud,
10-bit Mode, REFCLK = 2x Character Rate
0
0
0
8.33
16.67
MHz
REFCLK Clock Frequency—50 to 100 MBaud,
8-bit Mode, REFCLK = 2x Character Rate
0
0
1
10
20
MHz
REFCLK Clock Frequency—50 to 100 MBaud,
10-bit Mode, REFCLK = 4x Character Rate
0
1[21]
0
16.67
33.3
MHz
REFCLK Clock Frequency—50 to 100 MBaud,
8-bit Mode, REFCLK = 4x Character Rate
0
1[21]
1
20
40
MHz
REFCLK Clock Frequency—100 to 200 MBaud,
10-bit Mode, REFCLK = Character Rate
1
0
0
8.33
16.67
MHz
REFCLK Clock Frequency—100 to 200 MBaud,
8-bit Mode, REFCLK = Character Rate
1
0
1
10
20
MHz
REFCLK Clock Frequency—100 to 200 MBaud,
10-bit Mode, REFCLK = 2x Character Rate
1
1
0
16.67
33.3
MHz
REFCLK Clock Frequency—100 to 200 MBaud,
8-bit Mode, REFCLK = 2x Character Rate
1
1
1
20
40
MHz
120
ns
tREFCLK
REFCLK Period
25
tREFH
REFCLK HIGH Time
6.5
tREFL
REFCLK LOW Time
tREFRX
REFCLK Frequency Referenced to Received Clock Period[22]
ns
6.5
−0.04
ns
+0.04
%
CY7C9689A Receiver Switching Characteristics Over the Operating Range
Parameter
Description
tB[23]
Bit Time
tSA
Static Alignment[16, 24]
tEFW
Error Free Window[16, 25, 26]
tIN_J
IN± Peak-to-Peak Input Jitter Tolerance[16, 25, 27, 28]
Min.
20.0
Max.
Unit
5.0
ns
600
ps
0.65
UI
0.5
UI
Notes:
21. When configured for synchronous operation with the FIFOs bypassed (FIFOBYP is LOW), if RANGESEL is HIGH the SPDSEL input is ignored and operation
is forced to the 100–200 MBaud range.
22. REFCLK has no phase or frequency relationship with RXCLK and only acts as a centering reference to reduce clock synchronization time. REFCLK must be
within ±0.04% of the transmitter PLL reference (REFCLK) frequency, necessitating a ±200-PPM crystal.
23. The PECL switching threshold is the midpoint between the PECL− VOH, and VOL specification (approximately VDD − 1.33V).
24. Static alignment is a measure of the alignment of the Receiver sampling point to the center of a bit. Static alignment is measured by the absolute difference
of the left and right edge shifts (|tSH_L – tSH_R|) of one bit until a character error occurs.
25. Receiver UI (Unit Interval) is calculated as 1/(fREF*N) when operated in 8-bit mode (N = 10) and 10-bit mode (N = 12) if no data is being received, or 1/(fREF*N)
of the remote transmitter if data is being received. In an operating link this is equivalent to N * tB when REFCLK = 1X the character rate. An alternate multiply
ratios (2X or 4X, as selected by SPDSEL and RANGESEL), the numerator is multiplied by 2 or 4 respectively.
26. Error Free Window is a measure of the time window between bit centers where a transition may occur without causing a bit sampling error. EFW is measured
over the operating range, input jitter < 50% Dj.
27. The specification is sum of 25% Duty Cycle Distortion (DCD), 10% Data Dependant Jitter (DDJ), 15% Random Jitter (RJ).
28. Parallel data output specifications are only valid if all outputs are loaded with similar DC and AC loads.
Document #: 38-02020 Rev. *C
Page 24 of 46
CY7C9689A
CY7C9689A Transmitter Switching Characteristics Over the Operating Range
Parameter
tB[23]
tRISE
tFALL
tDJ
Description
Bit Time
[16]
PECL Output Rise Time 20−80% (PECL Test Load)
[16]
PECL Output Fall Time 80−20% (PECL Test Load)
Deterministic Jitter (peak-peak)
tRJ
Random Jitter
Min.
Max.
Unit
20.0
5.0
ns
200
1700
ps
200
1700
ps
0.02
UI
0.008
UI
0.08
UI
[16, 29]
(σ) [16, 30]
[16]
Transmitter Total Output Jitter (peak-peak)
tJT
CY7C9689A HOTLink Transmitter Switching Waveforms
Write Cycle
Asynchronous (FIFO) Interface
EXTFIFO = HIGH
tTXCLK
FIFOBYP = HIGH
tTXCPWH
tTXCPWL
TXCLK
tTXDS
TXHALT
TXSC/D
TXDATA[7:0]
TXDATA[9:8]/TXCMD[2:3]
TXCMD[1:0]
tTXDH
Note 31
tTXENH
NO OPERATION
TXEN
tTXENS
tTXA
TXFULL
TXHALF
TXEMPTY
tTXA
Write Cycle
Asynchronous (FIFO) Interface
EXTFIFO = LOW
FIFOBYP = HIGH
TXCLK
tTXDS
TXHALT
TXSC/D
TXDATA[7:0]
TXDATA[9:8]/TXCMD[2:3]
TXCMD[1:0]
tTXDH
Note 32
tTXENS
tTXENH
TXEN
NO OPERATION
tTXA
TXFULL
TXHALF
TXEMPTY
tTXA
Notes:
29. While sending continuous JK, outputs loaded to 50Ω to VDD − 1.3V, over the operating range.
30. While sending continuous HH, after 100,000 samples measured at the cross point of differential outputs, time referenced to REFCLK input, over the operating range.
31. When EXTFIFO is HIGH, the write data is captured on the clock cycle following TXEN = HIGH.
32. When EXTFIFO is LOW, the write data is captured on the same clock cycle as the TXEN = LOW.
Document #: 38-02020 Rev. *C
Page 25 of 46
CY7C9689A
CY7C9689A HOTLink Transmitter Switching Waveforms (continued)
OUTPUT ENABLE Timing
Asynchronous (FIFO) Interface
EXTFIFO = HIGH
FIFOBYP = HIGH
TXCLK
TXHALT
TXSC/D
TXDATA[7:0]
TXDATA[9:8]/TXCMD[2:3]
TXCMD[1:0]
NO OPERATION
TXEN
Note 33
tTXRSS
tTXRSH
TXRST
tTXCES
tTXCEH
CE
tTXOE
tTXOAZ
TXFULL
TXHALF
TXEMPTY
tTXOZA
OUTPUT ENABLE Timing
Asynchronous (FIFO) Interface
EXTFIFO = LOW
FIFOBYP = HIGH
TXCLK
TXHALT
TXSC/D
TXDATA[7:0]
XDATA[9:8]/TXCMD[2:3]
TXCMD[1:0]
TXEN
NO OPERATION
tTXRSS
CE
TXRST
tTXRSH
Note 33
tTXCES
tTXCEH
CE
TXRST
tTXOE
tTXOAZ
TXFULL
TXHALF
TXEMPTY
tTXOZA
Note:
33. Illustrates timing only. TXEN and TXRST not usually active in same time period.
Document #: 38-02020 Rev. *C
Page 26 of 46
CY7C9689A
CY7C9689A HOTLink Transmitter Switching Waveforms (continued)
Write Cycle
Synchronous Interface
EXTFIFO = HIGH
FIFOBYP = LOW
tREFCLK
tREFH
tREFL
REFCLK
tREFDS
TXHALT
TXSC/D
TXDATA[7:0]
XDATA[9:8]/TXCMD[2:3]
TXCMD[1:0]
tREFDH
Note 34
tREFENH
NO OPERATION
TXEN
tREFENS
tTRA
TXFULL
TXHALF
TXEMPTY
tTRA
Write Cycle
Synchronous Interface
EXTFIFO = LOW
FIFOBYP = LOW
REFCLK
tREFDS
TXHALT
TXSC/D
TXDATA[7:0]
DATA[9:8]/TXCMD[2:3]
TXCMD[1:0]
tREFDH
Note 35
tREFENS
TXEN
tREFENH
NO OPERATION
TXFULL
TXHALF
TXEMPTY
Notes:
34. When transferring data to the Transmitter input from a depth expanded external FIFO, the data is captured from the external FIFO one clock cycle following the
actual enable (TXEN = HIGH).
35. When transferring data to the Transmitter input from a synchronous external controller, the data is captured in the same clock cycle as the actual enable (TXEN
= LOW).
Document #: 38-02020 Rev. *C
Page 27 of 46
CY7C9689A
CY7C9689A HOTLink Transmitter Switching Waveforms (continued)
OUTPUT ENABLE Timing
Synchronous Interface
EXTFIFO = HIGH
FIFOBYP = LOW
REFCLK
TXHALT
TXSC/D
TXDATA[7:0]
TXDATA[9:8]/TXCMD[2:3]
TXCMD[1:0]
tREFENH
NO OPERATION
TXEN
tREFENS
tREFCES
tREFCEH
CE
tREFOE
tREFAZ
TXFULL
TXEMPTY
tREFZA
OUTPUT ENABLE Timing
Synchronous Interface
EXTFIFO = LOW
FIFOBYP = LOW
REFCLK
TXHALT
TXSC/D
TXDATA[7:0]
TXDATA[9:8]/TXCMD[2:3]
TXCMD[1:0]
TXEN
NO OPERATION
CE
TXFULL
TXEMPTY
Document #: 38-02020 Rev. *C
Page 28 of 46
CY7C9689A
CY7C9689A HOTLink Receiver Switching Waveforms
Read Cycle
Asynchronous (FIFO) Interface
EXTFIFO = HIGH
FIFOBYP = HIGH
tRXCLKOP
tRXCLKIP
tRXCLKOD
tRXCPWH
tRXCLKOD
tRXCPWL
RXCLK
tRXENH
tRXENS
RXEN
NO OPERATION
READ
READ
tRXA
tRXA
RXEMPTY
Note 36
FIFO EMPTY
RXFULL
RXHALF
RXDATA[7:0]
RXDATA[9:8/RXCMD[2:3]
RXCMD[1:0]
VALID DATA
Note 37
CE
Read Cycle
Asynchronous (FIFO) Interface
EXTFIFO = LOW
FIFOBYP = HIGH
RXCLK
tRXENS
RXEN
tRXENH
READ
tRXA
tRXA
FIFO EMPTY
RXEMPTY
RXFULL
RXHALF
RXDATA[7:0]
RXDATA[9:8/RXCMD[2:3]
RXCMD[1:0]
VALID DATA
Note 38
CE
Notes:
36. When transferring data from the Receive FIFO to a depth expanded external FIFO, the data is sent to the external FIFO on the same clock cycle that RXEN =
HIGH. RXEMPTY = LOW indicates that data is available.
37. On inhibited reads, or if the Receive FIFO goes empty, the data outputs do not change.
38. When reading data from synchronous data interface, the data is captured on any clock cycle that RXEN = LOW. RXEMPTY = HIGH indicates data is available.
RXEMPTY = LOW indicates that the FIFO is empty.
Document #: 38-02020 Rev. *C
Page 29 of 46
CY7C9689A
CY7C9689A HOTLink Receiver Switching Waveforms (continued)
Output Enable Timing
RXCLK
tRXENH
tRXENS
RXEN
NO OPERATION
Note 39
tRXRSH
tRXRSS
RXRST
tRXCES
tRXCEH
CE
tRXAZ
tRXOE
RXFULL
RXDATA[7:0]
RXDATA[9:8/RXCMD[2:3]
RXCMD[1:0]
Note 40
OLD DATA
tRXZA
tREFCLK
tREFL
tREFH
REFCLK
Static Alignment
Error-Free Window
tB/2− tSA
tB/2− tSA
tEFW
INA±
INB±
INA±
INB±
tB
BIT CENTER
SAMPLE WINDOW
BIT CENTER
Table 7. HOTLink TAXI-compatible Encoder Patterns
4B/5B Encoder
5B/6B Encoder
HEX
Data
4-bit Binary
Data[41]
0
1
2
0010
3
0011
4
0100
01010
5
0101
01011
5-bit Encoded
Symbol[42, 43]
HEX
Data
5-bit Binary
Data[41]
6-bit Encoded
Symbol[42, 43]
0000
11110
00
00000
110110
0001
01001
01
00001
010001
10100
02
00010
100100
10101
03
00011
100101
04
00100
010010
05
00101
010011
Notes:
39. Illustrates timing only. RXEN and RXRST not usually active in same time period.
40. Receive FIFO Reads are inhibited while the outputs are High-Z.
41. Binary Input Data is the parallel input data which is input to the Transmitter and output from the Receiver. Binary bits are listed from left to right in the following
order: 8-Bit mode (BYTE8/10 is HIGH and TXSC/D or RXSC/D is LOW)—TXDATA/RXDATA[7], [6], [5], [4], and TXDATA/RXDATA[3], [2], [1], [0]; 10-Bit mode
(BYTE8/10 is LOW and TXSC/D or RXSC/D is LOW)—TXDATA/RXDATA[8], [7], [6], [5], [4], and TXDATA/RXDATA[9], [3], [2], [1], [0].
42. The ENCODED Symbols are shown here as “ones and zeros”, but are converted to and from an NRZI stream at the transmitter output and receiver input.
NRZI represents a “one” as a state transition (either LOW-to-HIGH or HIGH-to-LOW) and a “zero” as no transition within the bit interval.
43. Encoded Serial Symbol bits are shifted out with the most significant bit (Left-most) of the most significant nibble coming out first.
Document #: 38-02020 Rev. *C
Page 30 of 46
CY7C9689A
Table 7. HOTLink TAXI-compatible Encoder Patterns (continued)
4B/5B Encoder
5B/6B Encoder
HEX
Data
4-bit Binary
Data[41]
5-bit Encoded
Symbol[42, 43]
HEX
Data
5-bit Binary
Data[41]
6-bit Encoded
Symbol[42, 43]
6
0110
01110
06
00110
010110
7
0111
01111
07
00111
010111
8
1000
10010
08
01000
100010
9
1001
10011
09
01001
110001
A
1010
10110
0A
01010
110111
B
1011
10111
0B
01011
100111
C
1100
11010
0C
01100
110010
D
1101
11011
0D
01101
110011
E
1110
11100
0E
01110
110100
F
1111
11101
0F
01111
110101
10
10000
111110
11
10001
011001
12
10010
101001
13
10011
101101
14
10100
011010
15
10101
011011
16
10110
011110
17
10111
011111
18
10001
101010
19
11001
101011
1A
11010
101110
1B
11011
101111
1C
11100
111010
1D
11101
111011
1E
11110
111100
1F
11111
111101
Table 8. HOTLink TAXI Compatible Command Symbols
CY7C9689A (Transmitter)
Command Input
TXCMD[3:0]
HEX
Binary CMD[44]
8-bit mode (BYTE8/10 is HIGH)
CY7C9689A (Receiver)
Command Output
RXCMD[3:0]
Encoded
Symbol[42, 43]
Mnemonic
HEX
Binary CMD[44]
0
1
0000
0001
11000 10001
11111 11111
JK (8-bit SYNC)
II
0
1
0000
0001
2
3
0010
0011
01101 01101
01101 11001
TT
TS
2
3
0010
0011
4
5
0100
0101
11111 00100
01101 00111
IH
TR
4
5
0100
0101
6
7
0110
0111
11001 00111
11001 11001
SR
SS
6
7
0110
0111
Note:
44. Binary CMD is the parallel input data which is input to the Transmitter and output from the Receiver. Binary bits are listed from left to right in the following order:
8-Bit mode (BYTE8/10 is HIGH and TXSC/D or RXSC/D is HIGH)—TXCMD/RXCMD[3], [2], [1], [0]; 10-Bit mode (BYTE8/10 is LOW and TXSC/D or RXSC/D
is HIGH)—TXCMD/RXCMD[1], [0].
Document #: 38-02020 Rev. *C
Page 31 of 46
CY7C9689A
Table 8. HOTLink TAXI Compatible Command Symbols (continued)
CY7C9689A (Transmitter)
Command Input
TXCMD[3:0]
CY7C9689A (Receiver)
Command Output
RXCMD[3:0]
8[45]
9[45]
1000
1001
00100 00100
00100 11111
HH
HI
8
9
1000
1001
A[45]
B
1010
1011
00100 00000
00111 00111
HQ
RR
A
B
1010
1011
C
D[45]
1100
1101
00111 11001
00000 00100
RS
QH
C
D
1100
1101
E[45]
F[45]
1110
1111
00000 11111
00000 00000
QI
QQ
E
F
1110
1111
10-bit mode (BYTE8/10 is LOW)
0
00
011000 100011
LM (10-bit SYNC)
0
00
1
2
01
10
111111 111111
011101 011101
I’I’
T’T’
1
2
01
10
3
11
011101 111001
T’S’
3
11
Functional Description
The interconnection of two or more CY7C9689A Transceivers
forms a general-purpose communications subsystem capable
of transporting user data at up to 20 MBytes per second over
several types of serial interface media. The CY7C9689A is
highly configurable with multiple modes of operation.
In the transmit section of the CY7C9689A, data moves from
the input register, through the Transmit FIFO, to the 4B/5B
Encoder. The encoded data is then shifted serially out the
OUTx± differential PECL compatible drivers. The bit-rate clock
is generated internally from a 2.5x, 5x, or 10x PLL clock multiplier. A more complete description is found in the section
CY7C9689A HOTLink Transmit-Path Operating Mode
Description.
In the receive section of the CY7C9689A, serial data is
sampled by the receiver on one of the INx± differential line
receiver inputs. The receiver clock and data recovery PLL
locks onto the selected serial bit stream and generates an
internal bit-rate sample clock. The bit stream is deserialized,
decoded, and presented to the Receive FIFO, along with a
character clock. The data in the FIFO can then be read either
slower or faster than the incoming character rate. A more
complete description is found in the section CY7C9689A
HOTLink Receive-Path Operating Mode Description.
The Transmitter and Receiver parallel interface timing and
functionality can be configured to Cascade directly to external
FIFOs for depth expansion, couple directly to registers, or
couple directly to state machines. These interfaces can accept
or output either:
• 8-bit characters
• 10-bit characters
• 10-bit pre-encoded characters (pre-scrambled or
pre-encoded)
• 12-bit pre-encoded characters (pre-scrambled or
pre-encoded).
The bit numbering and content of the parallel transmit interface
is shown in Table 1. When operated with the 4B/5B, 5B/6B
Encoder bypassed, the TXSC/D and RXSC/D bits are ignored.
The HOTLink Transceiver serial interface provides a seamless
interface to various types of media. A minimal number of
external passive components are required to properly
terminate transmission lines and provide LVPECL loads. For
power supply decoupling, a single capacitor (in the range of
0.02 µF to 0.1 µF) is required per power/ground pair. Additional
information on interfacing these components to various media
can be found in the HOTLink Design Considerations application note.
CY7C9689A TAXI HOTLink Transmit-Path
Operating Mode Descriptions
The TAXI HOTLink Transmitter can be configured into several
operating modes, each providing different capabilities and
fitting different transmission needs. These modes are selected
using the FIFOBYP, ENCBYP and BYTE8/10 inputs on the
CY7C9689A Transceiver. These modes can be reduced to five
primary classes:
• Synchronous Encoded
• Synchronous Pre-encoded
• Asynchronous Encoded
• Asynchronous Pre-encoded.
Note:
45. While these Commands are legal data and will not disrupt normal operation if used occasionally, they may cause data errors if grouped into recurrent fields.
Normal PLL operation cannot be guaranteed if one or more of these commands is continuously repeated.
Document #: 38-02020 Rev. *C
Page 32 of 46
CY7C9689A
Synchronous Encoded
In this mode, the Transmit FIFO is bypassed, while the 4B/5B,
5B/6B encoder is enabled. One character is accepted at the
Transmit Input Register at the rising edge of REFCLK, and
passed to the Encoder where it is encoded for serial transmission. The Serializer operates synchronous to REFCLK,
which is multiplied by 10 or 5 to generate the serial data
bit-clock. In this mode the TXRST and TXHALT inputs are not
interpreted and may be tied either HIGH or LOW. To place the
CY7C9689A into synchronous modes, FIFOBYP must be
LOW.
This mode is usually used for products that must meet specific
predefined protocol requirements, and cannot tolerate the
uncontrolled insertion of SYNC fill characters. The host
system is required to provide new data at every rising edge of
REFCLK (along with TXEN) to maintain the data stream. If
TXEN is not asserted, the Encoder is loaded with JK or LM
sync characters.
Input Register Mapping
In Encoded modes, the bits of the TXDATA input bus are
mapped into characters (as shown in Table 1), including a
TXSVS bit, eight bits of data, and a TXSC/D bit to select either
Special Character codes or Data characters.
The TXSC/D bit controls the encoding of the TXDATA[7:0] or
TXDATA[9:0] bits of each character. It is used to identify if the
input character represents a Data Character or a Special
Character code. If TXSC/D is LOW, the character appeared on
the TXDATA bus is encoded using the Data Character codes
listed in Table 7. If TXSC/D is HIGH, the character on the
TXCMD bus is encoded using the Special Character codes
listed in Table 8.
Synchronous Pre-encoded
In synchronous pre-encoded mode, both the Transmit FIFO
and the 4B/5B encoder are bypassed, and data passes directly
from the Transmit Input Register to the Serializer. The
Serializer operates synchronous to REFCLK, which is multiplied by 10 or 5 when BYTE8/10 is HIGH (as selected by the
SPDSEL and RANGESEL inputs) to generate the serial data
bit-clock. In this mode, part of the TXCMD bus inputs are used
as part of the data input bus. To place the CY7C9689A into
synchronous modes, FIFOBYP must be LOW.
This mode is usually used for products containing external
encoders or scramblers, that must meet specific protocol
requirements. The host system is required to provide new data
at every rising edge of the REFCLK (along with TXEN) to
maintain the data stream. If TXEN is not asserted, the
Serializer is loaded with JK or LM sync characters.
In this mode the LSB of each input character (TXDATA[0]) is
shifted out first, followed sequentially by TXDATA[1] through
TXDATA[9] (TXDATA[11] when BYTE8/10 is LOW).
Asynchronous Encoded
In Asynchronous Encoded mode, both the Transmit FIFO and
the Encoder are enabled. This provides 256 characters of data
buffering. The Serializer operates synchronous to REFCLK,
which is multiplied by 2.5, 5, or 10 to generate the serial data
bit-clock (as selected by SPDSEL and RANGESEL). In this
mode the TXRST and TXHALT inputs are interpreted.
This mode supports the same Input Register mapping as
Synchronous Encoded mode. Because both the Transmit
Document #: 38-02020 Rev. *C
FIFO and Encoder are enabled, the input FIFO may be loaded
at any rate supported by the FIFO (up to 50 MHz), without
generating any decoder errors at the receive end of the link.
CY7C9689A TAXI HOTLink Receive-Path
Operating Mode Descriptions
The HOTLink Receiver can be configured into several
operating modes, each providing different capabilities and
fitting different reception needs. These modes are selected
using the FIFOBYP, ENCBYP, BYTE8/10 inputs on the
CY7C9689A Transceiver. These modes can be reduced to
four primary classes:
• Synchronous Decoded
• Synchronous Undecoded
• Asynchronous Decoded
• Asynchronous Undecoded.
In all these modes, serial data is received at one of the differential line receiver inputs and routed to the Deserializer and
Framer. The PLL in the clock and data recovery block is used
to extract a bit-rate clock from the transitions in the data
stream, and uses that clock to capture bits from the serial
stream. These bits are passed to the Deserializer where they
are formed into 10- or 12-bit characters.
To align the incoming bit stream to the proper character boundaries, the Framer must be enabled by asserting RFEN HIGH.
The Framer logic-block checks the incoming bit stream for the
unique pattern that defines the character boundaries. This
logic filter looks for the JK or LM (when BYTE8/10 is LOW)
sync character. Once a sync character is found, the Framer
captures the offset of the data stream from the present
character boundaries, and resets the boundary to reflect this
new offset, thus framing the data to the correct character
boundaries.
Since noise induced errors can cause the incoming data to be
corrupted, and since many combinations of corrupt and legal
data can create an aliased sync character, the framer may also
be disabled by deasserting RFEN LOW.
Synchronous Decoded
In these modes, the Receive FIFO is bypassed, while the
5B/4B, 6B/5B Decoder is enabled. Framed characters output
from the Deserializer are decoded, and passed directly to the
Receive Output Register. The Deserializer operates
synchronous to the recovered bit-clock, which is divided by 10,
generate the output RXCLK clock. In this mode the RXRST
input is not interpreted and may be biased either HIGH or
LOW.
These modes are usually used for products that must meet
specific protocol requirements. New decoded characters are
provided at the RXDATA outputs once every rising edge of
RXCLK. If RXEMPTY is asserted LOW, the characters on the
RXCMD output register is a JK or LM sync character, and the
discard policy is set to non-0. Because the decoder is now
enabled, all received characters are checked for compliance
to the 4B/5B decoding rules.
Output Register Mapping
The RXDATA[11:0] output bus is mapped into a character
consisting of eight bits of data and four bits of command, or ten
bits of data and two bits of command. An accompanying
RXSC/D bit identifies the character as either command or
data.
Page 33 of 46
CY7C9689A
The Violation (VLTN) output indicates a code violation has
occured. When the VLTN output is asserted HIGH, this
indicates a transmission error is detected in the character at
the current transfer clock cycle.
Synchronous Undecoded
serial interface are written to the Receive FIFO before being
passed to the output register. The Deserializer operates
synchronous to the recovered bit-clock, which is divided by 10
(or 12) to generate the Receive FIFO write clock. Data is read
from the Receive FIFO, using the RXCLK input clock, when
addressed by CE and selected by RXEN.
In this mode, both the Receive FIFO and the 5B/4B, 6B/5B
Decoder are bypassed, and data passes directly from the
Deserializer to the output register. The Deserializer operates
synchronous to the recovered bit-clock, which is divided by 10
to generate the output RXCLK clock. In this mode the RXRST
input is not interpreted and may be biased either HIGH or
LOW.
These modes are usually used for products containing
external decoders or descramblers, that must meet specific
protocol requirements. New data may be read from the
Receive FIFO any time that the FIFO status flags indicate a
non-empty condition (RXEMPTY is deasserted). To ensure
that data is not lost, the Receive FIFO must be read faster than
data is loaded into the Receive FIFO.
This mode is usually used for products containing external
decoders or descramblers that must meet specific protocol
requirements. New data is provided at the RXDATA outputs
once every rising edge of RXCLK. Received characters are
not checked for any specific coding requirements and no
decoding errors are reported.
If the receiver is to provide framed characters, it is necessary
for the transmit end to include JK or LM sync characters in the
data stream. This can be done by:
• operating the transmitter in encoded mode and writing JK
or LM characters into the data stream
• operating the transmitter in pre-encoded mode and writing
the 10-bit value for an encoded JK (1100010001) or LM
(011000100011) character to the data stream
• not enabling the transmitter when it is operated in
synchronous mode, or by allowing the transit FIFO to go
empty when it is operated in asynchronous mode.
Asynchronous Decoded
In Asynchronous Decoded mode, both the Receive FIFO and
the Decoder of the CY7C9689A are enabled. The deserializer
operates synchronous to the recovered bit-clock, which is
divided by 10 to generate the Receive FIFO write clock.
Characters are read from the Receive FIFO, using the external
RXCLK input, when addressed by CE and selected by RXEN.
In this mode the RXRST input is interpreted.
Asynchronous Decoded mode supports the same Output
Register mapping as the Synchronous Decoded mode.
Because both the Receive FIFO and Decoder are enabled, the
output FIFO may be read at any rate supported by the FIFO,
however, if the Receive FIFO ever indicates a full condition
(RXFULL is asserted), data may be lost.
Asynchronous Undecoded
BIST Operation and Reporting
The CY7C9689ADX HOTLink Transceiver incorporates the
same Built-In Self-Test (BIST) capability. This link diagnostic
uses a Linear Feedback Shift Register (LFSR) to generate a
511-character repeating sequence that is compared,
character-for-character, at the receiver.
BIST mode is intended to check the entire high-speed serial
link at full link-speed, without the use of specialized and
expensive test equipment. The complete sequence of
characters used in BIST are documented in Table 4.
In Asynchronous Undecoded modes, the Receive FIFO is
enabled. This means that all characters received from the
Document #: 38-02020 Rev. *C
Page 34 of 46
CY7C9689A
TXCLK
TXBISTEN
TXEMPTY
TXHALF
TXFULL
Enable TX BIST
BIST
LOOP
REFCLK
LOW to enable FIFO Flags
LOW to enable VLTN reads
Ignore these outputs
ERROR
Start of RX
BIST Wait
Forced to indicate EMPTY by BIST
BIST
LOOP
Enable RX BIST
OUTB±
TXCMD[1:0]
TXSC/D
TXDATA[9:0]
TXEN
Don’t Care
Start of RX
BIST match
OUTA±
CE
RXEN
RXDATA[9:0]
RXSC/D
RXCMD[1:0]
VLTN
RXEMPTY
RXHALF
RXFULL
RXBISTEN
RXCLK
CY7C9689A
Start of TX BIST
INA±
INB±
A/B
HIGH to select A
Figure 5. Built-In Self-Test Illustration
BIST Enable Inputs
There are separate BIST enable inputs for the transmit and
receive paths of the CY7C9689A. These inputs are both active
LOW; i.e., BIST is enabled in its respective section of the
device when the BIST enable input is determined to be at a
logic-0 level. Both BIST enable inputs are asynchronous; i.e.,
they are synchronized inside the CY7C9689A to the internal
state machines.
BIST Transmit Path
The transmit path operation with BIST is controlled by the
TXBISTEN input and overrides most other inputs (see
Figure 5). When the Transmit FIFO is enabled (not bypassed)
and TXBISTEN is recognized internally, all reads from the
Transmit FIFO are suspended and the BIST generator is
enabled to sequence out the 511 character repeating BIST
sequence. If the recognition occurs in the middle of a data
field, the following data is not transmitted at that time, but
remains in the Transmit FIFO. Once the TXBISTEN signal is
removed, the data in the Transmit FIFO is again available for
transmission. To ensure proper data handling at the destination, the transmit host controller should either use TXHALT
to prevent transmission of data at specific boundaries, or allow
the Transmit FIFO to completely empty before enabling BIST.
With transmit BIST enabled, the Transmit FIFO remains
available for loading of data. It may be written up to its normal
maximum limit while the BIST operation takes place. To allow
removal of stale data from the Transmit FIFO, it may also be
reset during a BIST operation. The reset operation proceeds
Document #: 38-02020 Rev. *C
as documented, with the exception of the information
presented on the TXEMPTY FIFO status flag. Since this flag
is used to present BIST loop status, it continues to reflect the
state of the transmit BIST loop status until TXBISTEN is no
longer recognized internally. The completion of the reset
operation may still be monitored through the TXFULL FIFO
status flag.
The TXEMPTY flag, when used for transmit BIST progress
indication, continues to reflect the active HIGH or active LOW
settings determined by the UTOPIA or Cascade timing model
selected by EXTFIFO; i.e., when configured for the Cascade
timing model, the TXEMPTY and TXFULL FIFO flags are
active HIGH, when configured for the UTOPIA timing model
the TXEMPTY and TXFULL FIFO flags are active LOW. The
illustration in Figure 5 uses the UTOPIA conventions.
When TXBISTEN is first recognized, the TXEMPTY flag is
clocked to a reset state, regardless of the addressed state of
the Transmit FIFO (if CE is LOW or not), but is not driven out
of the part unless CE has been sampled asserted (LOW).
Following this, on each completed pass through the BIST loop,
the TXEMPTY flag is set for one interface clock period (TXCLK
or REFCLK).
The TXEMPTY flag remains set until the interface is
addressed and the state of TXEMPTY has been observed. If
the device is not addressed (CE is not sampled LOW), the flag
remains set internally regardless of the number of TXCLK
clock cycles that are processed. If the device status is not
polled on a sufficiently regular basis, it is possible for the host
system to miss one or more of these BIST loop indications.
Page 35 of 46
CY7C9689A
A pass through the loop is defined as that condition where the
Encoder generates the 0x00 (where 0x denotes Hex number,
e.g. 0x00 denotes HEX00) state. Depending on the initial state
of the BIST LFSR, the first pass through the loop may occur at
substantially less than 511 character periods. Following the
first pass, as long as TXBISTEN remains LOW, all remaining
passes are exactly 511 characters in length.
When the Transmit FIFO is bypassed, the interface is clocked
by the REFCLK signal instead of TXCLK. While the active or
asserted state of the TXEMPTY signal is still controlled by the
EXTFIFO, the state of any completed BIST loops is no longer
preserved. Instead, the TXEMPTY flag reflects the dynamic
state of the BIST loop progress, and is asserted only once
every 511 character periods. If the interface is not addressed
at the time that this occurs, then the FIFO status flags remain
in a high-Z state and the loop event is lost.
BIST Receive Path
The receive path operation in BIST is similar to that of the
transmit path. While the Receive FIFO is enabled (not
bypassed) and RXBISTEN is recognized internally, all writes
to the Receive FIFO are suspended.
Any data present in the Receive FIFO when RXBISTEN is
recognized remains in the FIFO and cannot be read until the
BIST operation is complete. The data in the Receive FIFO
remains valid, but is NOT available for reading through the
host parallel interface. This is because the error output
indicator for receive BIST operations is the VLTN signal, which
is normally part of the RXDATA bus. To prevent read operations while BIST is in operation, the RXEMPTY and RXHALF
flags are forced to indicate an Empty condition. Once
RXBISTEN has been removed and recognized internally, the
Receive FIFO status flags are updated to reflect the current
content status of the Receive FIFO.
To allow removal of stale data from the Receive FIFO, it may
be reset during a BIST operation. The reset operation
proceeds as documented, with the exception that the
RXEMPTY and RXHALF status flags already indicate an
empty condition. The RXFULL flag is used to present BIST
progress. The active (asserted) state on RXFULL (and
RXEMPTY) remain controlled by the present operating mode
and interface timing model (UTOPIA or Cascade).
When RXBISTEN has been recognized, RXFULL becomes
the receive BIST loop indicator (regardless of the logic state of
FIFOBYP). When RXBISTEN is first recognized, the RXFULL
flag is clocked to a set state, regardless of the addressed state
of the Receive FIFO (if CE is sampled LOW or not). Following
this, RXFULL remains set until the receiver detects the start of
the BIST pattern. Then RXFULL is deasserted for the duration
of the BIST pattern, pulsing asserted for one RXCLK period on
the last symbol of each BIST loop. If 14 of 28 consecutive
characters are received in error, RXFULL returns to the set
state until the start of a BIST sequence is again detected.
Just like the BIST status flag on the transmit data path, the
RXFULL flag captures the asserted states, and keeps them
until they are read. This means that if the status flag is not read
on a regular basis, events may be lost.
The detection of errors is presented on the VLTN output.
Unlike the RXFULL FIFO status flag, the active state of this
output is not controlled by the EXTFIFO input. With the
Receive FIFO enabled, these outputs should operate the
Document #: 38-02020 Rev. *C
same as the RXFULL flag, with respect to preserving the
detection state of an error until it is read.
Unlike the RXFULL flag, which only needs the CY7C9689A to
be addressed (CE sampled LOW by RXCLK) to enable the
RXFULL three-state driver, and an RXCLK to “read” the flag,
the VLTN output requires a selection (assertion of RXEN while
addressed) to enable the RXDATA bus three-state drivers.
The selection process is necessary to ensure that a multi-PHY
implementation does not enable multiple VLTN drivers at the
same time.
When the Receive FIFO is bypassed, the interface is clocked
by the RXCLK output signal. While the active or asserted state
of the RXFULL signal is still controlled by the EXTFIFO input,
the state of any completed BIST loops or detected errors are
no longer preserved. Instead, the RXFULL flag reflects the
dynamic state of the BIST loop progress, and is asserted only
once every 511 character periods. If the interface is not
addressed at the time that this occurs, then the FIFO status
flags remain in a high-Z state and the loop event is lost. This
is also true of the VLTN output, such that if the CY7C9689A
receive path is not selected to enable the RXDATA bus
three-state drivers, the detection of a BIST miscompare is lost.
BIST Three-state Control
When BIST is enabled on either the transmitter or the receiver,
the three-state enable signals for the BIST status flags and
error indicators work the same as for normal data processing.
The output drivers for the BIST status that is presented on
FIFO status flags are only enabled when CE has been
sampled asserted (LOW) by the respective clock (TXCLK,
RXCLK, or REFCLK).
To access the BIST error information, it is necessary to
perform a read cycle of the addressed receiver. This means
that CE must be LOW to enable the receiver (Rx_Match), and
RXEN must be asserted from HIGH to LOW to select the
device. Because the part is in BIST, no data is read from the
FIFO, but the data bus is driven. This allows the VLTN indicator
to be driven onto the RXDATA bus. So long as RXEN remains
asserted, the receiver stays selected, the data bus remains
driven, and VLTN has meaning.
Bus Interfacing
The parallel transmit and receive host interfaces to the
CY7C9689A are configurable for either synchronous or
asynchronous operation. Each of these configurations
supports two selectable timing and control models of Shared
Bus or Cascade.
All asynchronous bus configurations have the internal
Transmit and Receive FIFOs enabled. This allows data to be
written or read from these FIFOs at any rate up to the
maximum 50-MHz clock rate of the FIFOs. All internal operations of the CY7C9689A do not use the external TXCLK or
RXCLK, but instead make use of synthesized derivatives of
REFCLK for transmit path operations and a recovered
character clock for receive path operations.
All synchronous bus configurations require the bus interface
operations to be synchronous to REFCLK on the transmit path
and the recovered clock (output as RXCLK) on the receive
path. The internal FIFOs are bypassed in all synchronous
modes.
Page 36 of 46
CY7C9689A
The two supported timing and control models are Shared Bus
and Cascade. The Shared Bus is based on the timing model
of a FIFO with active LOW FIFO status flags and read/write
enables.
The Cascade timing model is a modification of the Shared Bus
model that changes the flags and FIFO read/write enables to
active HIGH. This model is present primarily to allow depth
expansion of the internal FIFO by direct coupling to external
CY7C42x5 synchronous FIFOs. To allow this direct coupling,
the cycle-to-cycle timing between the transmit and receive
enables (TXEN and RXEN) are also modified to ensure correct
data transfer.
These four configurations of bus operation and timing/control
can all be used with or without external FIFOs. Depending on
the specific mode selected, the amount of external hardware
necessary to properly couple the CY7C9689A to state
machines or external FIFOs is minimal in all cases, and may
be zero if the proper configuration is selected.
With only minor exceptions, all configurations of the
CY7C9689A in the Shared Bus mode borrowed concepts from
the ATM Forum’s UTOPIA Bus operation. concepts of
addressing and selection to control the enabled/disabled state
of the output drivers, and when data can be written to or read
from the part.
Shared Bus Interface Concept
The CY7C9689A Parallel Interface is designed for interfacing
to a Shared Bus. The maximum TXCLK and RXCLK frequency
is 50 MHz, which provides a total bandwidth of 50Million
characters per second in each direction. More than two
CY7C9689A can be serviced on the same bus at full serial line
speed.
The CY7C9689A is designed to be the Slave in Master-Slave
type of shared bus architecture. Generally, the bus Master (a
Medium Access Device, MAC) is a higher layer device that
sources out going data/command and sinks incoming
data/command to/from Slaves (CY7C9689A) on the shared
bus (see Figure 6).
Bus
Master
CE2
CY7C9689A
CY7C9689A
Device Selection
All actions on the Shared Bus interface are controlled by the
Chip Enable and selection states of the interface. These states
control the read and write access to the Receive and Transmit
FIFOs, access to the FIFO status flags, reset of the Transmit
and Receive FIFOs, and read and write access to the Serial
Address Register. The CY7C9689A supports the concept of
an “address match” through a single Chip Enable (CE) input.
Address Match and FIFO Flag Access
The CY7C9689A makes use of a single active-LOW Chip
Enable (CE) to generate address-match conditions. This
allows multiple CY7C9689A devices to share a common bus,
with device output three-state controls being managed by
either an address match condition (CE sampled LOW), or by
a selection state.
The Transmit and Receive FIFO flag output drivers are
enabled in any TXCLK, REFCLK, or RXCLK cycle following
CE being sampled asserted (LOW) by the rising edge of the
respective clock. The CE input is sampled separately by the
clocks for the transmit and receive interfaces, which allows
these clocks to be both asynchronous to each other, and to
operate at different clock rates. An example of both Transmit
and Receive FIFO flag access is shown in Figure 7.
TXCLK
CE
TXFULL
Valid
Transmit Port Addressing
RXCLK
CEn
CE1
accesses to Slaves which have room in the TXFIFOs. While
data is being transferred on the data/command bus, the bus
Master can continue to poll each Slave device independently.
CE
TXDATA/TXCMD
RXDATA/RXCMD
Status, Control
............
RXEMPTY
CY7C9689A
Valid
Receive Port Addressing
Figure 7. FIFO Flag Driver Enables
Figure 6. Shared Bus Architecture
The data bus (TXDATA, RXDATA), command bus (TXCMD,
RXCMD) and FIFO status flags (TXFULL, RXEMPTY, etc.) of
each CY7C9689A on the shared bus can be connected
together respectively. Each Slave can be assigned an
address. The address of each Slave can be decoded by a
decoder which drives the CE input of each Slave. The bus
Master will poll each Slave by selecting (or “Addressing”) the
device, and sample the FIFO flags. Depending on the FIFOs
status on each Slave device, the Master can schedule read
accesses to Slaves which have data in the RXFIFOs, and write
Document #: 38-02020 Rev. *C
When the Transmit FIFO is enabled (FIFOBYP is HIGH) and
CE is sampled LOW by the rising edge of TXCLK, the output
drivers for the TXFULL and TXEMPTY FIFO flags are
enabled. When CE is sampled HIGH by the rising edge of
TXCLK, these same output drivers are disabled.
When the Transmit FIFO is bypassed (FIFOBYP is LOW and
not in byte-packed mode) and CE is sampled LOW by the
rising edge of REFCLK, the output drivers for the TXFULL and
TXEMPTY FIFO flags are enabled. When CE is sampled
HIGH by the rising edge of REFCLK, the FIFO flag output
drivers are disabled.
Page 37 of 46
CY7C9689A
When CE is sampled LOW by the rising edge of RXCLK (input
or output), the output drivers for the RXFULL and RXEMPTY
FIFO flags are enabled. When CE is sampled HIGH by the
rising edge of RXCLK, the FIFO flag output drivers are
disabled.
Device Selection
The concept of selection is used to control the access to the
transmit and receive parallel-data ports of the device. There
are three primary types of selection:
• Transmit data selection (with and without internal Transmit
FIFO)
• Receive data selection (with and without internal Receive
FIFO)
• Continuous selection (for either or both transmit and receive
interfaces).
In addition to these normal selection types, there are two
additional sequences that are used to control the internal
Transmit and Receive FIFOs reset operations, and to control
read/write access to the Serial Address Register:
• Transmit reset sequence
• Receive reset sequence.
Of these operations, the transmit data selection and transmit
reset sequence are mutually exclusive and cannot exist at the
same time. The receive data selection and receive reset
sequence are also mutually exclusive and cannot exist at the
same time. Either transmit operation can exist at the same
time as either receive operation.
All normal forms of selection require that an Chip Enable must
be asserted (CE sampled LOW) either at the same time as the
selection control signal being sampled asserted, or one or
more clock cycles prior to the selection control signal being
sampled asserted.
Transmit Data Selection
Asynchronous With Shared Bus Timing and Control
(Transmit FIFO Enabled)
When CE is sampled LOW and TXRST is sampled HIGH by
the rising edge of TXCLK, a Tx_Match condition is generated.
This Tx_Match condition continues until CE is sampled HIGH
or TXRST is sampled LOW at the rising edge of TXCLK. When
a Tx_Match (or Tx_RstMatch) condition is present, the
TXEMPTY and TXFULL output drivers are enabled. When a
Tx_Match (or Tx_RstMatch) condition is not present, these
same drivers are disabled (High-Z).
The selection state of the Transmit FIFO is entered when a
Tx_Match condition is present, and TXEN transitions from
HIGH to LOW. Once selected, the Transmit FIFO remains
selected until TXEN is sampled HIGH by the rising edge of
TXCLK. In the selected state, data present on the TXDATA
inputs is captured and stored in the Transmit FIFO. This
transmit interface selection process is shown in Figure 8.
Synchronous With Shared Bus Timing and Control
(Transmit FIFO Bypassed)
When the Transmit FIFO is bypassed (FIFOBYP is LOW and
not in byte-packed mode), the CY7C9689A must still be
selected to write data into the Transmit Input Register.
When CE is sampled LOW and TXRST is sampled HIGH by
the rising edge of REFCLK, a Tx_Match condition is
generated. This Tx_Match condition continues until CE is
sampled HIGH or TXRST is sampled LOW at the rising edge
of REFCLK. When a Tx_Match (or Tx_RstMatch) condition is
present, the TXEMPTY and TXFULL output drivers are
enabled (with the Transmit FIFO bypassed, the status flags
normally indicate an Empty condition). When a Tx_Match (or
Tx_RstMatch) condition is not present, these same drivers are
disabled (High-Z).
TXCLK
TXRST
CE
[46]
Tx_Match
Note 47
TXEN
Tx_Selected
[46]
TXDATA/TXCMD
D1
(Shared Bus Timing)
TXDATA/TXCMD
(Cascade Timing)
TXFULL
Not Full
D2
D3
D1
D2
D3
Not Full
Note 47
Figure 8. Transmit Selection with Transmit FIFO Enabled
Document #: 38-02020 Rev. *C
Page 38 of 46
CY7C9689A
The selection state of the Transmit Input Register is entered
when a Tx_Match condition is present, and TXEN transitions
from HIGH to LOW. Once selected, the transmit input register
remains selected until TXEN is sampled HIGH by the rising
edge of REFCLK. In the selected state, data present on the
TXDATA inputs is captured in the Transmit Input Register and
passed to the Serializer or Encoder (as selected by the
ENCBYP input). This transmit interface selection process is
shown in Figure 9.
When the 4B/5B Encoder is enabled and data is not written to
the Transmit Input Register, the data stream is automatically
padded with JK or LM SYNC characters. When the 4B/5B,
5B/6B Encoder is disabled and no data is written to the
Transmit Input Register, JK or LM SYNC characters are also
automatically padded with SYNC characters.
Receive Data Selection
Asynchronous With Shared Bus Timing and Control
(Receive FIFO Enabled)
When CE is sampled LOW and RXRST is sampled HIGH by
the rising edge of RXCLK input, an Rx_Match condition is
generated. This Rx_Match condition continues until CE is
sampled HIGH or RXRST is sampled LOW at the rising edge
of RXCLK input. When an Rx_Match (or Rx_RstMatch)
condition is present, the RXEMPTY and RXFULL output
drivers are enabled.
When an Rx_Match (or Rx_RstMatch) condition is not
present, these same drivers are disabled (High-Z).
The selection state of the Receive FIFO is entered when an
Rx_Match condition is present, and RXEN transitions from
HIGH to LOW. Once selected, the Receive FIFO remains
selected until RXEN is sampled HIGH by the rising edge of
RXCLK input. The selected state initiates a read cycle from the
Receive FIFO and enables the Receive FIFO data onto the
RXDATA bus. This receive interface selection process is
shown in Figure 10.
REFCLK
TXRST
CE
Tx_Match
[46]
Note 47
TXEN
Tx_Selected
[46]
TXDATA/TXCMD
D1
(Shared Bus Timing)
TXDATA/TXCMD
(Cascade Timing)
TXFULL
Not Full
D2
D3
D1
D2
D3
Not Full
Note 47
Figure 9. Transmit Selection with Transmit FIFO Bypassed
Notes:
46. Signals labeled in italics are internal to the CY7C9689A.
47. Signals shown as dotted lines represent the differences in timing and active state of signals when operated in Cascade Timing.
Document #: 38-02020 Rev. *C
Page 39 of 46
CY7C9689A
Synchronous With UTOPIA Timing and Control
(Receive FIFO Bypassed)
When the Receive FIFO is bypassed (FIFOBYP is LOW), the
CY7C9689A must still be selected to enable the output drivers
for the RXDATA bus. With the Receive FIFO bypassed,
RXCLK becomes a synchronous output clock operating at the
character rate.
When CE is sampled LOW and RXRST is sampled HIGH by
the rising edge of RXCLK output, an Rx_Match condition is
generated. This Rx_Match condition continues until CE is
sampled HIGH or RXRST is sampled LOW at the rising edge
of RXCLK.
When an Rx_Match (or Rx_RstMatch) condition is present,
the RXEMPTY and RXFULL output drivers are enabled. With
the Receive FIFO bypassed, these flags normally indicate a
non-empty condition but may indicate empty if a JK or LM
SYNC character is present in the output register and the
receiver discard policy is non-0. When an Rx_Match (or
Rx_RstMatch) condition is not present, these same drivers are
disabled (High-Z).
The selection state of the Receive Output Register is entered
when an Rx_Match condition is present, and RXEN transitions
from HIGH to LOW. Once selected, the Receive Output
Register remains selected until RXEN is sampled HIGH by the
rising edge of RXCLK output. In the selected state, the output
drivers for the RXDATA outputs are enabled, and new data is
presented to the RXDATA bus on every clock cycle.
RXCLK
RXRST
CE
[46]
Rx_Match
RXEN
Rx_Selected
Note 47
[46]
RXDATA/RXCMD
D1
Not Empty
RXEMPTY
D2
D3
Not Empty
Note 47
Figure 10. Receive Selection with Receive FIFO Enabled
Continuous Selection
Continuous Selection is a specialized form of selection which
does not require sequenced assertion of CE and TXEN or
RXEN to select the device for data transfers. In this
Continuous Selection mode, the CE and associated TXEN or
RXEN enable signal must be asserted when the device is
powered up or during assertion of RESET. So long as these
signals remain asserted, the device remains selected and data
is accepted and presented on every clock cycle. Note: The
use of continuous selection makes it impossible to reset the
respective internal FIFOs, or to access the Serial Address
Register.
FIFO Reset Address Match
When CE and TXRST are both LOW, and this condition is
sampled by the rising edge of TXCLK, a Tx_RstMatch
condition is generated. This Tx_RstMatch condition continues
until CE or TXRST is sampled HIGH by the rising edge of
TXCLK. When a Tx_RstMatch (or Tx_Match) condition is
present, the TXEMPTY and TXFULL output drivers are
Document #: 38-02020 Rev. *C
enabled (just as in a normal Tx_Match condition). When a
Tx_RstMatch (or Tx_Match) condition is not present, these
same drivers are disabled (High-Z). The Transmit FIFO reset
Address Match is shown in Figure 11. Note that although
TXRST remains LOW for more than one clock cycle, the
Tx_RstMatch does not because the CE signal is no longer
asserted (LOW).
When CE and RXRST are both LOW, and this condition is
sampled by the rising edge of RXCLK, an Rx_RstMatch
condition is generated. This Rx_RstMatch condition continues
until CE or RXRST is sampled HIGH, at the rising edge of
RXCLK. When an Rx_RstMatch (or Rx_Match) condition is
present, the RXEMPTY and RXFULL output drivers are
enabled. When an Rx_RstMatch (or Rx_Match) condition is
not present, these same drivers are disabled (High-Z). The
Receive FIFO reset Address Match is shown in Figure 12.
Note that while the FIFO flags remain asserted for more than
one clock cycle, this is due to an Rx_Match condition, not a
continuation of the Rx_RstMatch.
Page 40 of 46
CY7C9689A
Transmit FIFO Reset Sequence
TXCLK
TXRST
CE
Tx_RstMatch
Tx_Match
[46]
[46]
TXFULL
Valid
Figure 11. Transmit FIFO Reset Address Match
RXCLK
RXRST
CE
Rx_RstMatch
Rx_Match
[46]
[46]
RXEMPTY
Valid Valid
Figure 12. Receive FIFO Reset Address Match
FIFO Reset Sequence
On power-up, the Transmitter and Receiver FIFOs are cleared
automatically. If the usage of the FIFOs in specific operating
modes results in stale or unwanted data, this data can be
cleared by resetting the respective FIFO. Data in the Transmit
FIFO will empty automatically if it is enabled to read the FIFO
(assuming TXHALT is not LOW). Stale received data can be
“flushed” by reading it, or the Receive FIFO can be reset to
remove the unwanted data.
The Transmit and Receive FIFOs are reset when the
Tx_RstMatch or Rx_RstMatch condition remains present for
eight consecutive clock cycles. Any disruption of the reset
sequence prior to reaching the eight cycle count, either by
removal of CE or the respective TXRST or RXRST, or
assertion of the associated TXEN or RXEN, terminates the
sequence and does not reset the FIFO. Because CE must
remain asserted during the reset sequence, the addressed
FIFO flags remain driven during the entire sequence.
Document #: 38-02020 Rev. *C
The Transmit FIFO reset sequence (see Figure 15) is started
when TXRST and CE are first sampled LOW by the rising edge
of TXCLK. Because a Tx_RstMatch condition is present, the
Transmit FIFO flags are asserted and can be used to track the
status of any Transmit FIFO reset in progress. Once the reset
sequence has reached its maximum count (eight TXCLK
cycles), the Transmit FIFO flags are asserted to indicate a
FULL condition (TXEMPTY is deasserted, and both TXHALF
and TXFULL are asserted). This indicates that the Transmit
FIFO reset has been recognized by the Transmit Control State
Machine and that a reset has been started. However, if the
TXEN is asserted prior to or during the assertion and sampling
of TXRST, the reset sequence is inhibited until TXEN is
removed. Note: The FIFO FULL state forced by the reset
operation is different from a FULL state caused by normal
FIFO data writes. For normal FIFO write operations, when
FULL is first asserted, the Transmit FIFO must still accept up
to four additional writes of data. When a FULL state is asserted
due to a Transmit FIFO reset operation, the FIFO will not
accept any additional data.
The Transmit FIFO reset does not complete until the external
reset condition is removed. This can be removed by
deassertion of either TXRST or CE. If CE is deasserted (HIGH)
to remove the reset condition, the Transmit FIFO flag’s drivers
are disabled, and the Transmit FIFO must be addressed at a
later time to validate completion of the Transmit FIFO reset. If
TXRST is deasserted (HIGH) to remove the reset condition,
the Tx_RstMatch is changed to a Tx_Match, and the Transmit
FIFO status flags remain driven. The Transmit FIFO reset
operation is complete when the Transmit FIFO flags indicate
an EMPTY state (TXEMPTY is asserted and both TXHALF
and TXFULL are deasserted). A valid Transmit FIFO reset
sequence is shown in Figure 15.
Here the TXRST and CE are asserted (LOW) at the same
time. When these signals are both sampled LOW by TXCLK,
a Tx_RstMatch condition is present. With TXEN deasserted
(HIGH), the Transmit FIFO is not selected for data transfers.
This Tx_RstMatch condition must remain for eight TXCLK
cycles to initiate the Tx_FIFO_Reset. Following this the
TXFULL FIFO status flag is asserted to indicate that the
Transmit FIFO reset sequence has completed and that a
Transmit FIFO reset is in progress.
When the TXRST signal is deasserted (HIGH), CE remains
LOW to allow the FIFO status flags to be driven. This allows
the completion of the reset operation to be monitored. To allow
better multi-tasking on multi-PHY implementations, it is
possible to deassert CE (HIGH) as soon as the FULL state is
indicated. The FIFO reset operation will complete and the
EMPTY state (indicating completion of the reset operation)
can be detected during a separate polling operation.
For those links implemented with a single PHY, it is possible
to hardwire CE LOW and still perform normal accesses and
reset operations. This is shown in Figure 13. In a single-PHY
implementation, a Transmit FIFO reset can never be initiated
with TXEN asserted at the same time as TXRST. Since CE is
always LOW, any assertion of TXEN causes the Transmit
FIFO to be selected, clearing the reset counter.
Page 41 of 46
CY7C9689A
TXCLK
TXRST
TXEN
Note 48
CE
Tx_RstMatch
[49]
[49]
Tx_Match
Tx_FIFO_Reset
[49]
TXFULL
Note 48
Not Full
Full
Figure 13. Transmit FIFO Reset Sequence with Constant CE
TXCLK
TXRST
Note 48
TXEN
CE
[49]
Tx_RstMatch
Tx_Match
Tx_FIFO_Reset
[49]
[49]
TXFULL
Note 48
Not Full
Figure 14. Invalid Transmit FIFO Reset Sequence with TXEN Asserted
Notes:
48. Signals shown as dotted lines indicate timing and levels when configured for external FIFOs (EXTFIFO is HIGH).
49. Signal names listed in italics are internal signals, shown for reference only.
Document #: 38-02020 Rev. *C
Page 42 of 46
CY7C9689A
TXCLK
TXRST
TXEN
Note 48
CE
[49]
Tx_RstMatch
[49]
Tx_Match
[49]
Tx_FIFO_Reset
TXFULL
Note 48
Not Full
Full
Figure 15. Transmit FIFO Reset Sequence
Figure 14 shows a sequence of input signals which will not
produce a FIFO reset. In this case TXEN was asserted to
select a Transmit FIFO for data transfers. Because TXEN
remains active, the assertion of CE and TXRST does not
initiate a reset operation. This is shown by the TXFULL flag
remaining HIGH (deasserted) following what would be the
normal expiration of the seven-state reset counter.
Receive FIFO Reset Sequence
The Receive FIFO reset sequence operates (for the most part)
the same as the Transmit FIFO reset sequence. The same
requirements exist for the assertion state of RXRST and
selection of the interface. A sample Receive FIFO reset
sequence is shown in Figure 16. Upon recognition of a
Receive FIFO reset, the Receive FIFO flags are forced to
indicate an EMPTY state to prohibit additional reads from the
FIFO. Unlike the Transmit FIFO, where the internal completion
of the reset operation is shown by first going FULL and later
going EMPTY when the internal reset is complete, there is no
secondary indication of the completion of the internal reset of
the Receive FIFO. The Receive FIFO is usable as soon as
new data is placed into it by the Receive Control State
Machine.
RXCLK
RXRST
RXEN
Note 48
CE
[49]
Rx_RstMatch
Rx_Match
Rx_FIFO_Reset
[49]
[49]
RXEMPTY
Note 48
Not Empty
Empty
Figure 16. Receive FIFO Reset Sequence
Document #: 38-02020 Rev. *C
Page 43 of 46
CY7C9689A
Printed Circuit Board Layout Suggestions
Power Supply Bypass
0.01-µF MLC X7R
1206 Chip Cap (4 sites)
INA±
OUTA±
OUTB±
INB±
Power Supply Bypass
0.01-µF MLC X7R
CURSETB
Resistor
CURSETA
Resistor
Power Supply Bypass
0.01-µF MLC X7R
1206 Chip Cap (2 sites)
RXSC/D
REFCLK
CY7C9689A-AC
CY7C9689A-AC
Power Supply Bypass
0.01-µF MLC X7R
RESET
Power Supply Bypass
0.01-µF MLC X7R
Via to VDD plane
Via to VSS plane
This is a typical printed circuit board layout showing example
placement of power supply bypass components and other
components mounted on the same side as the CY7C9689A.
Other layouts, including cases with components mounted on
the reverse side would work as well.
Ordering Information
Package Name
Package Type
Operating Range
CY7C9689A-AC
Ordering Code
A100
100-lead Thin Quad Flat Pack
Commercial
CY7C9689A-AI
A100
100-lead Thin Quad Flat Pack
Industrial
Document #: 38-02020 Rev. *C
Page 44 of 46
CY7C9689A
Package Diagram
100-pin Thin Plastic Quad Flat Pack (TQFP) A100
51-85048-B
HOTLink is a registered trademark of Cypress Semiconductor, Inc. AMD, TAXI, and TAXIchip are trademarks of Advanced Micro
Devices. Inc. All product and company names mentioned in this document are trademarks of their respective holders.
Document #: 38-02020 Rev. *C
Page 45 of 46
© Cypress Semiconductor Corporation, 2002. The information contained herein is subject to change without notice. Cypress Semiconductor Corporation assumes no responsibility for the use
of any circuitry other than circuitry embodied in a Cypress Semiconductor product. Nor does it convey or imply any license under patent or other rights. Cypress Semiconductor does not authorize
its products for use as critical components in life-support systems where a malfunction or failure may reasonably be expected to result in significant injury to the user. The inclusion of Cypress
Semiconductor products in life-support systems application implies that the manufacturer assumes all risk of such use and in doing so indemnifies Cypress Semiconductor against all charges.
CY7C9689A
Document Title: CY7C9689A TAXI™-compatible HOTLink Transceiver
Document Number: 38-02020
REV.
ECN NO.
Issue
Date
Orig. of
Change
Description of Change
**
106249
04/20/01
SZV
Change from Spec number: 38-00758 to 38-02020
*A
107695
06/28/01
SPN
Changed part number: CY7C9689 to CY7C9689A
*B
113563
04/10/02
REV
Removed parity reference
Deleted mention of Byte-packer
Fixed formatting to change mF to µF
*C
118318
11/08/02
REV
Changed pins 23 and 29 to RXDATA[11:10]/RXCMD[1:0]
LFI was changed from “three state” to just output pin
Fixed flip flop to Q as output and D as input
Font problem with up-arrow symbols corrected
Document #: 38-02020 Rev. *C
Page 46 of 46