MAXIM MAX3982 User Manual

General Description

The MAX3982 is a single-channel, copper-cable preem­phasis driver that operates from 1Gbps to 4.25Gbps. It
provides compensation for copper links, such as

4.25Gbps Fibre Channel, allowing spans of up to 15m
with 24AWG. The cable driver provides four selectable
preemphasis levels. The input compensates for up to
10in of FR4 circuit board material at 4.25Gbps.

The MAX3982 also features SFP-compliant loss-of-signal
detection with selectable sensitivity and TX_DISABLE.
Selectable output swing reduces EMI and power con­sumption. It is packaged in a 3mm x 3mm, 16-pin thin
QFN and operates from 0°C to +85°C temperature range.

Applications

SFP Active Copper-Cable Assemblies

Backplanes

1.0625Gbps, 2.125Gbps, and 4.25Gbps Fibre
Channel

1.25Gbps Ethernet

2.488Gbps STM16

InfiniBand

PCI Express

Features

♦ Drives Up to 15m with 24AWG Cable

♦ Drives Up to 30in of FR4

♦ 0.25W Total Power with +3.3V Supply

♦ Selectable 1600mV

P-P

or 1200mV

P-P

Differential

Output Swing

♦ Selectable Output Preemphasis

♦ Fixed Input Equalization

♦ Loss-of-Signal Detection with Selectable

Sensitivity

♦ Transmit Disable

MAX3982

SFP Copper-Cable Preemphasis Driver

________________________________________________________________ Maxim Integrated Products 1

Ordering Information

19-3354; Rev 2; 2/06

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.

EVALUATION KIT

AVAILABLE

PART

TEMP

RANGE

PIN­PACKAGE

PKG

CODE

MAX3982UTE

16 Thin QFN

T1633-4

MAX3982UTE+

16 Thin QFN

T1633-4

MAX3982

+3.3V

TX_DISABLE
PE0
PE1
LOSLEV

IN+

OUTLEV

IN-

LOS

OUT+

OUT-

0.01μF

0.01μF

V

CC

OR

GND

SWITCH OR

SERDES

T

X+

T

X-

4.25Gbps LIMITING
AMPLIFIER

+3.3V

OUT+

OUT-

IN+

IN-

LOS

0.01μF

0.01μF

R

X+

R

X-

≤ 5V

≥4.7kΩ

V

CC

GND

V

CC

GND

4.25Gbps LIMITING
AMPLIFIER

+3.3V

TX_DISABLE

PE0
PE1

LOSLEV

IN+

OUTLEV

IN-

LOS

OUT+

OUT-

0.01μF

0.01μF

0.01μF

0.01μF

MAX3982

+3.3V

OUT+

OUT-

IN+

IN-

LOS

0.01μF

0.01μF

0.01μF

0.01μF

V

CC

GND

V

CC

GND

SWITCH OR

SERDES

R

X+

R

X-

T

X+

T

X-

DISK

ENCLOSURE

FABRIC SWITCH

V

CC

OR

GND

≤ 5V

≥ 4.7kΩ

COPPER-CABLE

DIFFERENTIAL 100Ω TWIN-AX

SFP ACTIVE CABLE ASSEMBLY

≤ 15m (24AWG)
UP TO 4.25Gbps

Typical Application Circuit

Pin Configuration appears at end of data sheet.

+Denotes lead-free package.

0°C to +85°C

0°C to +85°C

MAX3982

SFP Copper-Cable Preemphasis Driver

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VCC= +3.0V to +3.6V, TA= 0°C to +85°C. Typical values are at TA= +25°C and VCC= +3.3V, 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, VCC..............................................-0.5V to +6.0V

Continuous CML Output Current

at OUT+, OUT-..............................................-25mA to +25mA

Voltage at IN+, IN-, LOSLEV, LOS,

TX_DISABLE, PE0, PE1, OUTLEV ..........-0.5V to (V

CC

+ 0.5V)

LOS Open Collector Supply Voltage

with ≥ 4.7kΩ Pullup Resistor..............................-0.5V to +5.5V

Continuous Power Dissipation at +85°C

(derate 20.8mW/°C above +85°C).................................1.35W

Operating Junction Temperature Range (T

J

) ....-55C° to +150°C

Storage Ambient Temperature Range (T

S

) .......-55C° to +150°C

PARAMETER

CONDITIONS

Supply Current TX_DISABLE=low 75 97 mA

Inrush Current Current beyond steady-state current 10 mA

Power-On-Reset Delay t

POR

140ms

OPERATING CONDITIONS

Supply Voltage V

CC

3.0 3.3 3.6 V

Supply-Noise Tolerance 1MHz ≤ f < 2GHz 40

Operating Ambient Temperature

T

A

02585°C

Bit Rate NRZ data (Note 1) 1.0

CID Consecutive identical digits (bits) (Note 1) 10 Bits

CONTROL INPUTS: TX_DISABLE, PE0, PE1, OUTLEV, LOSLEV

Voltage, Logic High V

IH

2.0 V

Voltage, Logic Low V

IL

0.8 V

Current, Logic High I

IH

VIH = VCC + 0.5V

µA

Current, Logic Low I

IL

VIL = 0.8V

µA

STATUS OUTPUT: LOS

LOS asserted 0 25 µA

LOS unasserted, VOL ≤ 0.4V with 4.7kΩ
pullup resistor, pullup supply = 5.5V

1.0 mA

LOS Open Collector Current Sink

VCC = 0V, pullup supply = 5.5V, external
pullup resistor ≥ 4.7kΩ

025µA

LOSLEV = high (Note 1)

LOS Assert Level

LOSLEV = low (Note 1) 50

LOSLEV = high (Note 1)

LOS Deassert Level

LOSLEV = low (Note 1)

LOSLEV = high (Note 1) 20

LOS Hysteresis

LOSLEV = low (Note 1) 4

LOS Response Time

Time from IN dropping below assert level,
or rising above deassert level to 50% point
of LOS

10 µs

LOS Transition Time

Rise-time or fall-time (10% to 90%), external
pullup resistor = 4.7kΩ

ns

SYMBOL

MIN TYP MAX UNITS

100 mV

250

mV

P-P

4.25 Gbps

-150

350

P-P

mV

P-P

300 mV

120 mV

mV

mV

P-P

P-P

P-P

P-P

MAX3982

SFP Copper-Cable Preemphasis Driver

_______________________________________________________________________________________ 3

Note 1: Guaranteed by design and characterization.
Note 2: PE1 = PE0 = 1 for maximum preemphasis, load is 50Ω ±1% at each side, and the pattern is 0000011111 at 1Gbps.
Note 3: Measured at point B in Figure 2 using 0000011111 at 1Gbps. PE1 = PE0 = 0 for minimum preemphasis. For transition time,

the 0% reference level is the steady-state level after four zeros, just before the transition. The 100% reference level is the
maximum voltage of the transition.

Note 4: Tested with CJTPAT, as well as this pattern: 19 zeros, 1, 10 zeros, 1010101010 (D21.5 character), 1100000101 (K28.5+

character), 19 ones, 0, 10 ones, 0101010101 (D10.2 character), 0011111010 (K28.5 character).

Note 5: Cables are unequalized, Amphenol Spectra-Strip 24AWG. Residual deterministic jitter is the difference between the source

jitter at point A, and load jitter at point D in Figure 2. The deterministic jitter at the output of the transmission line must be
from media-induced loss and not from clock-source modulation.

ELECTRICAL CHARACTERISTICS (continued)

(VCC= +3.0V to +3.6V, TA= 0°C to +85°C. Typical values are at TA= +25°C and VCC= +3.3V, unless otherwise noted.)

PARAMETER

CONDITIONS

UNITS

EQUALIZER AND CABLE DRIVER SPECIFICATIONS

Input Swing

Measured differentially at point A of Figure
2 (Note 1)

mV

P-P

Input Resistance Measured differentially 85

Ω

Input Return Loss 100MHz to 2GHz (Note 1) 10 dB

TX_DISABLE = low,
OUTLEV = high

TX_DISABLE = low,
OUTLEV = low

Differential Output Swing

Measured
differentially at point
B of Figure 2
(Notes 1, 2)

40

mV

P-P

Common-Mode Output

high (Notes 1, 2)

60

mV

P-P

Output Resistance OUT+ or OUT- to VCC, single ended 42 50 58 Ω

Output Return Loss 100MHz to 2GHz (Note 1) 10 dB

Output Transition Time tr, t

f

20% to 80% (Notes 1, 3) 50 80 ps

Random Jitter (Notes 1, 3) 1.6

ps

RMS

2

4

8

Output Preemphasis See Figure 1

14

dB

Source to IN

Residual Output Deterministic
Jitter at 1.0625Gbps to

2.125Gbps (Notes 1, 4, 5)

6 mil
FR4 ≤ 10in

UI

P-P

Source to IN

Residual Output Deterministic

Jitter at 4.25Gbps (Notes 1, 4, 5)

6 mil
FR4 ≤ 10in

UI

P-P

SYMBOL

TX_DISABLE = high

(OUT+) + (OUT-), measured at point B of
Figure 2; TX_DISABLE = low, OUTLEV =

PE1 PE0

00

OUT to Load PE1 PE0

1m, 24AWG 0 0

5m, 24AWG 0 1

10m, 24AWG 1 0

15m, 24AWG 1 1

OUT to Load PE1 PE0

1m, 24AWG 0 0

5m, 24AWG 0 1

10m, 24AWG 1 0

15m, 24AWG 1 1

01

10

11

MIN TYP MAX

600 2000

100 115

1450 1800

1000 1350

0.10 0.15

0.15 0.20

MAX3982

SFP Copper-Cable Preemphasis Driver

4 _______________________________________________________________________________________

Figure 1. Illustration of Tx Preemphasis in dB

Figure 2. Test Setup. The points labeled A, B, and D are referenced for AC parameter test conditions. Deterministic jitter and eye
diagrams measured at point D.

V

LOW_PP

V

HIGH_PP

⎡

PE dB

( ) log

⎢

=

20

⎢
⎣

SIGNAL

SOURCE

SMA CONNECTORS

OSCILLOSCOPE OR

ERROR DETECTOR

A

⎛

V

HIGH PP

⎜
⎜

V

⎝

LOW PP

⎤

⎞

_

⎥

⎟
⎟

⎥

⎠

_

⎦

6 mil

1in ≤ L ≤ 10in

TEST SETUP

PCBOARD (FR4)

MAX3982

IN OUT

L ≤ 1in

6 mil

L = 2in

B

24AWG 100Ω TWIN-AX

SMA CONNECTORS

6 mil

FR4

≤ 4.4

4.0 ≤ ε

R

D

tan δ = 0.022

MAX3982

SFP Copper-Cable Preemphasis Driver

_______________________________________________________________________________________ 5

Figure 3. End-to-End Test Setup Using the MAX3748 as a Receiver. Deterministic jitter and eye diagrams measured at point D.

SIGNAL

SOURCE

1in ≤ L ≤ 12in

L ≤ 1in

IN OUT

6 mil

6 mil

L = 2in

L ≤ 1in

PC BOARD (FR4)

A

D

OSCILLOSCOPE OR

ERROR DETECTOR

B

SMA CONNECTORS

24AWG 100Ω TWIN-AX

TEST SETUP

SMA CONNECTORS

FR4

4.0 ≤ ε

R

≤ 4.4

tan δ = 0.022

MAX3982

6 mil

22pF

22pF

39Ω

39Ω

OUT IN

MAX3748

Typical Operating Characteristics

(VCC= +3.3V, TA= +25°C, unless otherwise noted. PRBS7 + 100CID pattern is PRBS 27, 100 zeros, 1010, PRBS 27, 100 ones, 0101.)

TRANSIENT RESPONSE

MAX3982 toc01

A = 2dB, PE = 00
B = 4dB, PE = 01

C = 8dB, PE = 10
D = 14dB, PE = 11

4.25Gbps K28.7 PATTERN
OUTLEV = HIGH

A
B
C
D

D
C
B
A

END-TO-END DETERMINISTIC JITTER

vs. CABLE LENGTH AT 4.25Gbps

MAX3982 toc02

CABLE LENGTH (m)

DETERMINISTIC JITTER (UI)

15105

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0

020

4.25Gbps PRBS7 + 100CID

PE[1,0] = 00

PE[1,0] = 01

PE[1,0] = 10

PE[1,0] = 11

12in FR4 AT INPUT
USING MAX3748 AS
RECEIVER, AS SHOWN
IN FIGURE 3

END-TO-END DETERMINISTIC JITTER

vs. CABLE LENGTH AT 2.125Gbps

MAX3982 toc03

CABLE LENGTH (m)

DETERMINISTIC JITTER (UI)

15105

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0

020

2.125Gbps PRBS7 + 100CID

PE[1,0] = 01

PE[1,0] = 10

PE[1,0] = 11

12in FR4 AT INPUT
USING MAX3748 AS RECEIVER,
AS SHOWN IN FIGURE 3

PE[1,0] = 00