CY7B923
CY7B933
In systems that require the outputs to be shut off during some
periods when link transmission is prohibited (e.g., for laser
safety functions), the FOTO input can be asserted. While it is
possible to insure that the output state of the PECL drivers is
LOW (i.e., light is off) by sending all 0’s in Bypass mode, it is
often inconvenient to insert this level of control into the data
transmission channel, and it is impossible in Encoded mode.
FOTO is provided to simplify and augment this control function
(typically found in laser-based transmission systems). FOTO
will force OUTA+ and OUTB+ to go LOW, OUTA− and OUTB−
to go HIGH, while allowing OUTC±to continue to function normal-
ly (OUTC is typically used as a diagnostic feedback and cannot be
disabled). This separation of function allows various system configu-
rations without undue load on the control function or data channel
logic.
rial data output is controlled by an internal Phase-Locked Loop
that multiplies the frequency of CKW by ten (10) to maintain
the proper bit clock frequency. The jitter characteristics (in-
cluding both PLL and logic components) are shown below:
Deterministic Jitter (D) < 35 ps (peak-peak). Typically mea-
j
sured while sending a continuous K28.5 (C5.0).
Random Jitter (R ) < 175 ps (peak-peak). Typically measured
j
while sending a continuous K28.7 (C7.0).
Transmitter Test Mode Description
The CY7B923 Transmitter offers two types of test mode oper-
ation, BIST mode and Test mode. In a normal system applica-
tion, the Built-In Self-Test (BIST) mode can be used to check
the functionality of the Transmitter, the Receiver, and the link
connecting them. This mode is available with minimal impact
on user system logic, and can be used as part of the normal
system diagnostics. Typical connections and timing are shown
in Figure 7.
Transmitter Serial Data Characteristics
The CY7B923 HOTLink Transmitter serial output conforms to
the requirements of the Fibre Channel specification. The se-
.01UF
4 9 22
7
VCC
Tx PECL Load
.01UF
Config
MODE
VCC
82
130
25
5
24
23
8
Fiber Optic
Tx
FOTO
BISTEN
ENN
Fiber
TX
A
B
27
26
Control
&
Status
OUTA+
OUTA–
TX+
TX–
ENA
RP
82
130
CY7B923
Transmitter
GND
Unused Output Left
Open to Minimize
Power Dissipation
28
1
.01UF
19
18
17
16
15
14
13
12
11
10
21
OUTB+
OUTB–
SC/D (Da)
D0 (Db)
D1 (Dc)
D2 (Dd)
D3 (De)
D4 (Di)
D5 (Df)
D6 (Dg)
D7 (Dh)
SVS(Dj)
CKW
Tx PECL Load
3
2
Coax or
Twisted Pair
OUTC+
OUTC–
270
A
B
Data
270
270
270
.01UF
GND
6 20
649
1500
Transmission
Line
Termination
RL/2
RL/2
Coax or
Twisted Pair
.01UF
C
9 2124
VCC
26
25
MODE
REFCLK
D
E
Config
Optional
Signal Det.
4
23
3
5
BISTEN
SO
A/B
RF
RDY
Control
&
Status
CY7B933
Receiver
28
27
7
IB+
IB–
E
19
18
17
16
15
14
13
12
11
10
22
270
130
SC/D (Qa)
D0 (Qb)
D1 (Qc)
D2 (Qd)
D3 (Qe)
D4 (Qi)
.01UF
VCC
Fiber
82
Fiber Optic
Rx
SIG
RX+
RX–
2
1
C
D
RX
IA+
IA–
Data
82
130
D5 (Qf)
GND
D6 (Qg)
D7 (Qh)
RVS(Qj)
.01UF
CKR
GND
Fiber Optic
PECL Load
6 8 20
B923–22
Figure 6. HOTLink Connection Diagram
16
CYPRESS [ CYPRESS ]
