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General Description

The MAX3840 is a dual 2

2 asynchronous crosspoint

switch for SDH/SONET DWDM and other high-speed
data switching applications where serial data stream
loop-through and protection channel switching are
required. It is ideal for OC-48 systems with forward
error correction. A high-bandwidth, fully differential sig-
nal path minimizes jitter accumulation, crosstalk, and
signal skew. Each 2

2 crosspoint switch can fan out

and/or multiplex up to 2.7Gbps data and 2.7GHz clock
signals. All inputs and outputs are current mode logic
(CML) compatible and easily adaptable to interface
with an AC-coupled LVPECL signal. When not used,
each CML output stage can be powered down with an
enable control to conserve power. The typical power
consumption is 460mW with all outputs enabled.

The MAX3840 is compatible with the MAX3876
2.5Gbps clock and data recovery (CDR) circuit.

The MAX3840 is available in a 32-pin exposed-pad
QFN package (5mm

5mm footprint) and operates

from a +3.3V supply over a temperature range of -40°C
to +85°C.

________________________Applications

SDH/SONET and DWDM Transport Systems

Add-Drop Multiplexers

ATM Switch Cores

WDM Cross-Connects

High-Speed Backplanes

Features

o Single +3.3V Supply
o 460mW Power Consumption
o 2ps

RMS

Random Jitter

o 7ps

P-P

Deterministic Jitter

o Power-Down Feature for Deselected Outputs
o CML Inputs/Outputs
o 6ps Channel-to-Channel Skew
o 100ps Output Edge Speed
o 5mm

5mm 32 QFN Package

MAX3840

+3.3V, 2.7Gbps Dual 2

2 Crosspoint Switch

________________________________________________________________ Maxim Integrated Products

MAX3866

TIA AND LA

MAX3876

CDR

MAX3840

CROSSPOINT

SWITCH

= 50

TRANSMISSION LINE

DATA

CLOCK

MAX3866

TIA AND LA

MAX3876

CDR

DATA

CLOCK

MAX3869

LASER

DRIVER

LASER

DRIVER

= +3.3V

Typical Application Circuit

19-1854; Rev 1; 11/01

Ordering Information

PART

TEMP RANGE

PIN-PACKAGE

MAX3840EGJ

-40

°C TO +85°C

32 QFN

Pin Configuration appears at end of data sheet.

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.

MAX3840

+3.3V, 2.7Gbps Dual 2

2 Crosspoint Switch

_______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

DC ELECTRICAL CHARACTERISTICS

= +3.0V to +3.6V, T

= -40°C to +85°C. Typical values are at V

= +3.3V, T

= +25°C, unless otherwise noted.)

Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.

Supply Voltage, V

.............................................-0.5V to +5.0V

Input Voltage (CML) .........................(VCC - 1.0) to (V

+ 0.5V)

TTL Control Input Voltage...........................-0.5V to (V

+ 0.5V)

Output Currents (CML) .......................................................22mA
Continuous Power Dissipation at T

= +85°C

32-Pin QFN (derate 29.4mW/°C)...................................1.9W

Operating Temperature Range ...........................-40°C to +85°C
Operating Junction Temperature Range ...........-55°C to +150°C
Storage Temperature Range .............................-65°C to +160°C
Lead Temperature (soldering, 10s) .................................+300°C

PARAMETER

SYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

Supply Current

All outputs enabled

140

190

CML INPUT AND OUTPUT SPECIFICATIONS

CML Differential Output Swing

= 50

to V

(Figure 2)

640

800

1000

P-P

Differential Output Impedance

100

115

CML Output Common-Mode
Voltage

= 50

to V

- 0.2

CML Single-Ended Input
Voltage Range

- 0.8 V

+ 0.4

CML Differential Input Voltage
Swing

300

1600

P-P

CML Single-Ended Input
Impedance

42.5

57.5

TTL SPECIFICATIONS

TTL Input High Voltage

2.0

TTL Input Low Voltage

0.8

TTL Input High Current

-10

+10

µA

TTL Input Low Current

-10

+10

µA

MAX3840

+3.3V, 2.7Gbps Dual 2

2 Crosspoint Switch

_______________________________________________________________________________________

AC ELECTRICAL CHARACTERISTICS

= +3.0V to +3.6V, T

= -40°C to +85°C. Typical values are at V

= +3.3V, T

= +25°C, unless otherwise noted.) (Note 1)

PARAMETER

SYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

CML Input and Output Data
Rate

2.7

Gbps

CML Input and Output Clock
Rate

2.7

GHz

CML Output Rise and Fall Time

, t

20% to 80%

100 136

CML Output Random Jitter

(Note 2)

RMS

CML Output Deterministic Jitter

(Note 3)

CML Output Differential Skew

skew1

Any differential pair

CML Output Channel-to-
Channel Skew

skew2

Any two outputs

Propagation Delay from Input-
to-Output

185

Note 1: AC characteristics are guaranteed by design and characterization.
Note 2: Measured with 100mV

P-P

noise (f

2MHz) on the power supply.

Note 3: Deterministic jitter (DJ) is the arithmetic sum of pattern-dependent jitter and pulse width distortion.

MAX3840

+3.3V, 2.7Gbps Dual 2

2 Crosspoint Switch

_______________________________________________________________________________________

SUPPLY CURRENT vs. TEMPERATURE

MAX3840 toc01

120

140

100

160

SUPPLY CURRENT (mA)

-50

-10

-30

TEMPERATURE (

°C)

4 OUTPUTS ENABLED

3 OUTPUTS ENABLED

2 OUTPUTS ENABLED

1 OUTPUT ENABLED

0 OUTPUTS ENABLED

CML DIFFERENTIAL VOLTAGE

MAX3840 toc02

200

250

400

350

300

650

600

700

750

550

500

450

800

CML DIFFERENTIAL VOLTAGE (mV

P-P

)

-50

-10

-30

TEMPERATURE (

°C)

-50

-10

-30

CHANNEL-TO-CHANNEL SKEW

vs. TEMPERATURE

MAX3840 toc04

TEMPERATURE (

°C)

TMIE (ps)

CHANNEL A

CHANNEL B

2.7Gbps EYE DIAGRAM

MAX3840 toc03

54ps/div

150mV/div

INPUT = 2

- 1PRBS

Typical Operating Characteristics

= +3.3V, T

= +25°C, unless otherwise noted.)

MAX3840

+3.3V, 2.7Gbps Dual 2

2 Crosspoint Switch

_______________________________________________________________________________________

Pin Description

PIN

NAME

FUNCTION

ENB1

Channel B1 Output Enable, TTL Input. A TTL low input powers down B1 output stage.

DIB1+

Channel B1 Positive Signal Input, CML

DIB1-

Channel B1 Negative Signal Input, CML

ENB0

Channel B0 Output Enable, TTL Input. A TTL low input powers down B0 output stage.

SELB0

Channel B0 Output Select, TTL Input. See Table 1.

DIB0+

Channel B0 Positive Signal Input, CML

DIB0-

Channel B0 Negative Signal Input, CML

SELB1

Channel B1 Output Select, TTL Input. See Table 1.

9, 24

GND

Supply Ground

10, 13, 16, 17,

20, 23

Positive Supply

DOB0-

Channel B0 Negative Output, CML

DOB0+

Channel B0 Positive Output, CML

DOB1-

Channel B1 Negative Output, CML

DOB1+

Channel B1 Positive Output, CML

DOA1-

Channel A1 Negative Output, CML

DOA1+

Channel A1 Positive Output, CML

DOA0-

Channel A0 Negative Output, CML

DOA0+

Channel A0 Positive Output, CML

SELA1

Channel A1 Output Select, TTL Input. See Table 1.

DIA0+

Channel A0 Positive Signal Input, CML

DIA0-

Channel A0 Negative Signal Input, CML

SELA0

Channel A0 Output Select, TTL Input. See Table 1.

ENA0

Channel A0 Output Enable, TTL Input. A TTL low input powers down A0 output stage.

DIA1+

Channel A1 Positive Signal Input, CML

DIA1-

Channel A1 Negative Signal Input, CML

ENA1

Channel A1 Output Enable, TTL Input. A TTL low input powers down A1 output stage.

Exposed Pad

Ground. The exposed pad must be soldered to the circuit board ground for proper
electrical and thermal operation.

Part Number MAX3840