Special Operation Functions:
Pre
Amp
Pre
Amp
Post
Amp
Rx Vout &
Emphasis
Post
Amp
Rx Vout &
Emphasis
Rx
CDR
Rx
CDR
µcontroller
µcontroller
Laser
Driver
Tx EQ
Laser
Driver
Tx EQ
Tx
CDR
Tx
CDR
Figure 2a. OWRAP Functionality (i2c controlled)
Figure 2b. EWRAP Functionality (i2c controlled)
Electrical and optical high speed data “wrap” functions are enabled to assist with local host or remote diagnostic and
optimization sequences. Optical data wrap (OWRAP) takes a received optical signal through a CDR jitter cleanup and
retransmits it optically out. Electrical data wrap (EWRAP) takes an incoming electrical signal through a CDR jitter cleanup
and retransmits it electrically out. An optional pass-through function is available to transmit outbound the wrapped
information, controlled through i2c commands.
Pre
Amp
Pre
Amp
Post
Amp
Rx Vout &
Emphasis
Post
Amp
Rx Vout &
Emphasis
Rx
CDR
Rx
CDR
µcontroller
µcontroller
i2c setting
i2c setting
Laser
Driver
Tx EQ
Laser
Driver
Tx EQ
Tx
CDR
Tx
CDR
Figure 2c. SFP Tx Variable Input Electrical EQ (i2c controlled)
Figure 2d. SFP Rx Variable Output Electrical Emphasis (i2c controlled)
The electrical SFP input stage (TD +/-) has been enhanced with features to allow host control and optimization of the
transceiver’s input equalization settings. The host can then select, in situ, the most appropriate SFP setting for a given
interconnect scenario.
The SFP electrical output stage (RD+/-) has been enhanced with variable output emphasis features to allow host control
and optimization of the receiver’s output settings. The host can then select, in situ, the most appropriate SFP setting for
a given interconnect scenario. To assist with optimizing the receiver output setting, the user can have data transmitted
by the SFP to a host ASIC by using EWRAP to loop back host generated traffic or can use a remotely generated optical
signal as a data source for SFP and interconnect training.
Table 2. Rate Select Function
Function
State
Explanation
Rx Rate Select
RS(0)
High
Receive Rate Select HIGH engages the internal Rx CDR. The CDR will look for valid 16GFC traffic and
lock within 500us when found. Due to differences in coding, this CDR will not be able to lock on valid
8GFC or 4GFC traffic.
Low
Receive Rate Select LOW bypasses the internal Rx CDR. This is intended for use only with 8GFC and
4GFC traffic. When set low, the SFP behaves like a legacy SFP.
Tx Rate Select
RS(1)
High
Transmit Rate Select HIGH engages the internal Tx CDR. The CDR will look for valid 16GFC traffic and
lock within 500us when found. Due to differences in coding, this CDR will not be able to lock on valid
8GFC or 4GFC traffic.
Low
Transmit Rate Select LOW bypasses the internal Tx CDR. This is intended for use only with 8GFC and
4GFC traffic. When set low, the SFP behaves like a legacy SFP.
Note: During Fibre Channel Link Speed Negotiation sequences, the host will control Tx Rate and Rx Rate inputs separately to accomplish link initial-
ization. Once speed negotiation is complete, it is expected both Tx Rate and Rx Rate will be placed in the same state by the host.
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