
6.5 Gbps
Dual Buffer Mux/Demux
AD8155
Rev. 0
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FEATURES
Dual 2:1 mux/1:2 demux
Optimized for dc to 6.5 Gbps NRZ data
Per-lane P/N pair inversion for routing ease
Programmable input equalization
Compensates up to 40 inches of FR4
Loss-of-signal detection
Programmable output preemphasis up to 12 dB
Programmable output levels with squelch and disable
Accepts ac-coupled or dc-coupled differential CML inputs
50 Ω on-chip termination
1:2 demux supports unicast or bicast operation
Port-level loopback
Port or single lane switching
1.8 V to 3.3 V flexible core supply
User-settable I/O supply from VCC to 1.2 V
Low power, typically 2.0 W in basic configuration
64-lead LFCSP
40°C to +85°C operating temperature range
APPLICATIONS
Low cost redundancy switch
SONET OC48/SDH16 and lower data rates
RXAUI, 4× Fibre Channel, Infiniband, and GbE over
backplane
OIF CEI 6.25 Gbps over backplane
Serial data-level shift
2-/4-/6-lane equalizers or redrivers
FUNCTIONAL BLOCK DIAGRAM
Ix_B[1:0]
Ox_B[1:0]
TRANSMIT
PRE-
EMPHASIS
DUAL
2:1
MULTIPLEXER/
1:2
DEMULTIPLEXER
RECEIVE
EQUALIZATION
CONTROL
LOGIC
TRANSMIT
PRE-
EMPHASIS
RECEIVE
EQUALIZATION
Ox_C[1:0]
Ix_C[1:0]
LB_A
Ox_A[1:0]
Ix_A[1:0]
EQ
2:1
EQ
1:2
LB_B
LB_C
PE_A
PE_B
PE_C
EQ_A
EQ_B
EQ_C
SEL[1:0]
BICAST
SEL4G
LOS_INT
AD8155
RESET
I2C
CONTROL
LOGIC
SCL
SDA
I2C_A[2:0]
08
26
2-
0
01
Figure 1.
GENERAL DESCRIPTION
The AD8155 is an asynchronous, protocol-agnostic, dual-lane
2:1 switch with a total of six differential CML inputs and
six differential CML outputs. The signal path supports NRZ
signaling with data rates up to 6.5 Gbps per lane. Each lane
offers programmable receive equalization, programmable
output preemphasis, programmable output levels, and loss-of-
signal detection.
The nonblocking switch core of the AD8155 implements a
2:1 multiplexer and 1:2 demultiplexer per lane and supports
independent lane switching through the two select pins,
SEL[1:0]. Each port is a two-lane link. Every lane implements
an asynchronous path supporting dc to 6.5 Gbps NRZ data,
fully independent of other lanes. The AD8155 has low latency
and very low lane-to-lane skew.
The main application of the AD8155 is to support redundancy
on both the backplane and the line interface sides of a serial
link. The demultiplexing path implements unicast and bicast
capability, allowing the part to support either 1 + 1 or 1:1
redundancy.
The AD8155 is also suited for testing high speed serial links
because of its ability to duplicate incoming data. In a port-
monitoring application, the AD8155 can maintain link
connectivity with a pass-through connection from Port C to
Port A while sending a duplicate copy of the data to test
equipment on Port B.
The rich feature set of the AD8155 can be controlled either
through external toggle pins or by setting on-chip control
registers through the I2C interface.