6.25 Gbps, 4 × 4,

Digital Crosspoint Switch with EQ

AD8156

Rev. 0

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FEATURES

4 × 4, fully differential, nonblocking array

Configurable for dual 2 × 2 operation

DC to 6.25 Gbps per channel, NRZ data rate

Programmable input equalization compensates for over 40”

of FR-4 at 6.25 Gbps

Multicast and broadcast modes of operation

Programmable output swing

100 mV p-p to 1.6 V p-p differential

Power supply: 3.3 V (±10%)

Low power

No EQ: 400 mW typical

Maximum EQ: 700 mW typical

Inputs: ac-coupled or dc-coupled

Wide set of dc-coupled input standards

3.3 V/2.5 V/1.8 V CML or 3.3 V LVPECL

Control: LVTTL- or LVCMOS-compatible

Low additive jitter: 25 ps p-p typical

Low random jitter: 0.8 ps rms

Integrated 50 Ω termination impedance at inputs/outputs

Individual output disable for power savings

49-ball, 8 mm × 8 mm BGA, 1 mm pitch

APPLICATIONS

Backplane equalization

SONET/SDH

Gigabit Ethernet

XAUI

Fibre Channel

FUNCTIONAL BLOCK DIAGRAM

EQ

4

4

CS

RST

UPD

WE

RE

MODE

D[3:0]

A[3:0]

CONTROL

LOGIC

AD8156

IN0P/N

IN1P/N

IN2P/N

IN3P/N

OUT0P/N

OUT1P/N

OUT2P/N

OUT3P/N

EQ

EQ

EQ

OUTPUT

DRIVERS

INPUT

RECEIVERS

INPUT

EQUALIZATION

4 × 4

SWITCH

Figure 1.

GENERAL DESCRIPTION

The AD8156, a member of the Xstream line of products, is a

high speed, fully differential, digital crosspoint switch. The part

can function as a 4 × 4 crosspoint switch with double-latched

memory, allowing simultaneous updates, or as a dual 2 × 2 with

direct output control. The AD8156 has low power dissipation,

typically 700 mW on 3.3 V with all outputs and input equalizers

active. It operates at any data rate from dc to 6.25 Gbps per port.

Each input channel on the AD8156 has a programmable input

equalizer to compensate for signal loss over a backplane.

The AD8156 high speed inputs are compatible with both ac-

coupled and dc-coupled 3.3 V, 2.5 V, or 1.8 V CML, as well as

3.3 V LVPECL data levels. The control interface is LVTTL- and

LVCMOS-compatible at 3.3 V. All input and output termination

resistors are integrated for ease of layout and to minimize

impedance mismatch. Input equalization and unused outputs

can be individually disabled to minimize power dissipation.

The AD8156 is packaged in a 49-ball, 8 mm × 8 mm, BGA

package with a 1 mm ball pitch. It operates over the industrial

temperature range of −40°C to 85°C.