MAXIM MAX3983

19-2928; Rev 0; 7/03
Quad Copper-Cable Signal Conditioner
Features
♦ Link Features
Span 20m with 24AWG, 15m with 28AWG
Span 0.5m of FR4 on Each Host
1.6W Total Power with 3.3V Supply
Loopback Function
♦ Cable Driver Features
Selectable Output Preemphasis
FR4 Input Equalization
Signal Detect for Each Channel
Output Disable
♦ Cable Receiver Features
Selectable FR4 Output Preemphasis
Cable Input Equalization
Signal Detect for Each Channel
Output Disable
Applications
4x InfiniBand (4 x 2.5Gbps)
Ordering Information
10Gbase-CX4 Ethernet (4 x 3.125Gbps)
10G Fibre Channel XAUI (4 x 3.1875Gbps)
PART
4x Copper-Cable or Backplane Transmission
(1Gbps to 3.2Gbps)
TEMP RANGE
MAX3983UGK
0°C to +85°C
PINPACKAGE
PKG CODE
68 QFN
G6800-4
Pin Configuration appears at end of data sheet.
Typical Application Circuit
4x COPPER CABLE ASSEMBLY
≤20m (24AWG)
≤15m (28AWG)
3.3V
≤0.5m
0.01µF
0.01µF
TX_IN1
TX
SERDES
RX
VCC[1:4]
TX_OUT1
TX_IN2
TX_OUT2
TX_IN3
TX_OUT3
TX_IN4
TX_OUT4
TO MAX3983
RX_OUT1
RX_IN1
RX_OUT2
RX_IN2
RX_OUT3
RX_IN3
RX_OUT4
RX_IN4
TX_PE0
VCC OR
GND
TX_ENABLE
RX_ENABLE
TX_PE1
RX_PE
3V TO 5.5V
3V TO 5.5V
POR
CPOR
TO HOST
LOOPBACK
4.7kΩ
4.7kΩ
MAX3983
RX_SD1
TX_SD1
RX_SD2
TX_SD2
RX_SD3
TX_SD3
RX_SD4
TX_SD4
GND
TO HOST
________________________________________________________________ Maxim Integrated Products
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.
1
MAX3983
General Description
The MAX3983 is a quad copper-cable signal conditioner
that operates from 2.5Gbps to 3.2Gbps. It provides compensation for 4x copper InfiniBand and 10Gbase-CX4
Ethernet links, allowing spans of 20m with 24AWG and
15m with 28AWG. The cable driver section provides four
selectable preemphasis levels. The input to the cable
driver compensates for up to 0.5m of FR4 circuit board
material. The cable receiver section provides additional
fixed input equalization while offering selectable preemphasis to drive FR4 circuit boards up to 0.5m.
The MAX3983 also features signal detection on all eight
inputs and internal loopback that allows for diagnostic
testing. It is packaged in a 10mm x 10mm, 68-pin QFN
and operates from 0°C to +85°C.
MAX3983
Quad Copper-Cable Signal Conditioner
ABSOLUTE MAXIMUM RATINGS
Supply Voltage, VCC..............................................-0.5V to +6.0V
Continuous CML Output Current at
TX_OUT[1:4]±, RX_OUT[1:4]± ..........................……….±25mA
Voltage at TX_IN[1:4]±, RX_IN[1:4]±, RX_SD[1:4],
TX_SD[1:4], RX_ENABLE, TX_ENABLE, RX_PE,
TX_PE[0:1], LOOPBACK, POR
(with series resistor ≥4.7kΩ)...................-0.5V to (VCC + 0.5V)
Continuous Power Dissipation (TA = +85°C)
68-Pin QFN (derate 41.7mW/°C above +85°C) ………….2.7W
Operating Junction Temperature Range (TJ) ....-55°C to +150°C
Storage Ambient Temperature Range (TS) .......-55°C to +150°C
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.
ELECTRICAL CHARACTERISTICS
(VCC = +3.0V to +3.6V, TA = 0°C to +85°C. Typical values are at VCC = +3.3V and TA = +25°C, unless otherwise noted.)
PARAMETER
SYMBOL
Supply Current
TYP
MAX
RX_EN = VCC, TX_EN = 0V
CONDITIONS
MIN
360
430
RX_EN = 0V, TX_EN = VCC
365
430
RX_EN = VCC, TX_EN = VCC
495
580
3.3
3.6
UNITS
mA
OPERATING CONDITIONS
Supply Voltage
VCC
Operating Ambient Temperature
3.0
1MHz ≤ f < 2GHz
Supply Noise Tolerance
TA
40
0
Bit Rate
NRZ data (Note 1)
CID
Consecutive identical digits (bits)
25
2.5
V
mVP-P
85
°C
3.2
Gbps
10
Bits
25
µA
STATUS OUTPUTS: RX_SD[1:4], TX_SD[1:4]
Signal detect asserted
Signal-Detect Open-Collector
Current Sink
0
Signal detect unasserted VOL ≤ 0.4V with 4.7kΩ
pullup resistor
1.0
VCC = 0V, pullup supply = 5.5V, external pullup
resistor ≥4.7kΩ
0
1.11
mA
25
µA
Time from RX_IN[1:4] or TX_IN[1:4] dropping
below 85mVP-P or rising above 175mVP-P to
50% point of signal detect
0.35
Signal-Detect Transition Time
Rise time or fall time (10% to 90%)
200
ns
Power-On Reset Delay
1µF capacitor on POR to GND
6
ms
Signal-Detect Response Time
µs
CONTROL INPUTS: RX_ENABLE, TX_ENABLE, RX_PE, TX_PE0, TX_PE1, LOOPBACK
Voltage, Logic High
VIH
Voltage, Logic Low
VIL
Current, Logic High
IIH
VIH = VCC
-150
+150
µA
Current, Logic Low
IIL
VIL = 0V
-150
+150
µA
2
1.5
V
0.5
_______________________________________________________________________________________
V
Quad Copper-Cable Signal Conditioner
(VCC = +3.0V to +3.6V, TA = 0°C to +85°C. Typical values are at VCC = +3.3V and TA = +25°C, unless otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
1600
mVP-P
115
Ω
TX SECTION (CABLE DRIVER)
PC Board Input Swing
Measured differentially at the signal source
(Note 1)
800
Input Resistance
TX_IN[1:4]+ to TX_IN[1:4]-, differential
85
Input Return Loss
100MHz to 2GHz (Note 1)
TX_ENABLE = high (Notes 1, 2)
Output Swing
100
10
17
1300
1500
TX_ENABLE = low
Output Resistance
Output Return Loss
Output Transition Time
Random Jitter
tr, tf
30
TX_OUT[1:4]+ or TX_OUT[1:4]- to VCC, single
ended
42
50
100MHz to 2GHz (Note 1)
10
13
20% to 80% (Notes 1, 3)
(Notes 1, 3)
Output Preemphasis
See Figure 1
Source to
TX_IN
Residual Output Deterministic
Jitter at 2.5Gbps (Notes 1, 4, 5)
6-mil FR4 ≤
20in
Source to
TX_IN
Residual Output Deterministic
Jitter at 3.2Gbps (Notes 1, 4, 5)
6-mil FR4 ≤
20in
dB
1600
TX_PE1
TX_PE0
0
0
3
0
1
6
1
0
9
1
1
12
TX_OUT to
Load
TX_PE1 TX_PE0
1m, 28AWG
0
0
5m, 28AWG
0
1
10m, 24AWG
1
0
15m, 24AWG
1
1
TX_OUT to
Load
58
mVP-P
Ω
dB
80
ps
1.6
psRMS
dB
0.10
0.15
UIP-P
0.15
0.20
UIP-P
TX_PE1 TX_PE0
1m, 28AWG
0
0
5m, 28AWG
0
1
10m, 24AWG
1
0
15m, 24AWG
1
1
Signal-Detect Assert Level
TX_IN for TX_SD = high (Note 6)
Signal-Detect Off
TX_IN for TX_SD = low (Note 6)
800
mVP-P
200
mVP-P
RX SECTION (CABLE RECEIVER)
Cable Input Swing
Measured differentially at the signal source
(Note 1)
1000
1600
mVP-P
Input Vertical Eye Opening
Measured differentially at the input of the
MAX3983 (Note 1)
175
1600
mVP-P
Input Resistance
RX_IN[1:4]+ to RX_IN[1:4]-, differential
85
100
Input Return Loss
100MHz to 2GHz (Note 1)
10
18
115
Ω
dB
_______________________________________________________________________________________
3
MAX3983
ELECTRICAL CHARACTERISTICS (continued)
ELECTRICAL CHARACTERISTICS (continued)
(VCC = +3.0V to +3.6V, TA = 0°C to +85°C. Typical values are at VCC = +3.3V and TA = +25°C, unless otherwise noted.)
PARAMETER
SYMBOL
Output Swing
Output Return Loss
Random Jitter
Output Preemphasis
tr, tf
42
100MHz to 2GHz (Note 1)
10
20% to 80% (Notes 1, 8)
MAX
1500
50
RX_PE = low
3
RX_PE = high
6
RX_OUT to
Load
58
15
45
(Notes 1, 8)
UNITS
mVP-P
Ω
dB
80
ps
1.6
psRMS
dB
RX_PE
5m, 28AWG
0in, 6-mil FR4
IB Cable
Assembly
without
20in, 6-mil FR4
preemphasis
Source to
RX_IN
Residual Output Deterministic
Jitter at 3.2Gbps
(Notes 1, 5, 9, 10)
TYP
30
RX_OUT[1:4]+ or RX_OUT[1:4]- to VCC, single
ended
Source to
RX_IN
Residual Output Deterministic
Jitter at 2.5Gbps
(Notes 1, 5, 9, 10)
MIN
1100
RX_ENABLE = low
Output Resistance
Output Transition Time
CONDITIONS
RX_ENABLE = high (Notes 1, 7)
0
0.10
0.15
UIP-P
0.15
0.20
UIP-P
1
RX_OUT to
Load
RX_PE
5m, 28AWG
0in, 6-mil FR4
IB cable
assembly
without
20in, 6-mil FR4
preemphasis
0
1
Signal-Detect Assert Level
RX_IN for RX_SD = high (Note 11)
Signal-Detect Off
RX_IN for RX_SD = low (Note 11)
175
mVP-P
85
mVP-P
4
RX_PE
6-mil FR4 ≤
20in
1m, 24AWG
0
0
0in
0
15m, 24AWG
1
1
20in
1
20m, 24AWG
1
1
20in
1
TX_OUT to
RX_IN
TX_PE0
Residual Output Deterministic
Jitter at 2.5Gbps
(Notes 1, 12, 13, 14)
Source to
TX_IN
RX_OUT to Load
END-TO-END JITTER (TX AND RX COMBINED PERFORMANCE)
TX_PE1
MAX3983
Quad Copper-Cable Signal Conditioner
0.15
0.20
0.2
0.25
_______________________________________________________________________________________
UIP-P
Quad Copper-Cable Signal Conditioner
(VCC = +3.0V to +3.6V, TA = 0°C to +85°C. Typical values are at VCC = +3.3V and TA = +25°C, unless otherwise noted.)
6-mil FR4 ≤
20 in
Note 1:
Note 2:
Note 3:
Note 4:
Note 5:
Note 6:
Note 7:
Note 8:
Note 9:
Note 10:
Note 11:
Note 12:
Note 13:
Note 14:
RX_PE
RX_OUT to Load
Source to
TX_IN
MIN
TX_PE0
CONDITIONS
TX_PE1
Residual Output Deterministic
Jitter at 3.2Gbps
(Notes 1, 12, 13, 14)
SYMBOL
TX_OUT to RX_IN
PARAMETER
1m, 24AWG
0
0
5in
0
15m, 24AWG
1
1
20in
1
20m, 24AWG
1
1
20in
1
TYP
MAX
0.20
0.25
0.25
0.3
UNITS
UIP-P
Guaranteed by design and characterization.
Measured with 2in of FR4 through InfiniBand connector with TX_PE1 = TX_PE0 =1.
Measured at the chip using 0000011111 or equivalent pattern. TX_PE1 = TX_PE0 = 0 for minimum preemphasis.
All channels under test are not transmitting during test. Channel tested with XAUI CJPAT, 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).
Cables are unequalized, Amphenol Spectra-Strip 24AWG and 28AWG or equivalent equipped with Fujitsu “MicroGiga”
connector or equivalent. All other channels are quiet. Residual deterministic jitter is the difference between the source jitter and the output jitter at the load. The deterministic jitter (DJ) at the output of the transmission line must be from mediainduced loss and not from clock-source modulation. Depending upon the system environment, better results can be
achieved by selecting different preemphasis levels.
Tested with a 1GHz sine wave applied at TX_IN under test with less than 5in of FR4.
Measured with 3in of FR4 with RX_PE = 1.
Measured at the chip using 0000011111 or equivalent pattern. RX_PE = low (minimum). Signal source is 1VP-P with 5m,
28AWG InfiniBand cable.
All other receive channels are quiet. TX_ENABLE = 0. Channel tested with XAUI CJPAT 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).
FR4 board material: 6-mil-wide, 100Ω, edge-coupled stripline (tanδ = 0.022, 4.0 < εR < 4.4).
Tested with a 1GHz sine wave applied at RX_IN under test with less than 5in of FR4.
Channel tested with XAUI CJPAT 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).
Cables are unequalized, Amphenol Spectra-Strip 24AWG or equivalent equipped with Fujitsu “MicroGiga” connector or
equivalent. Residual deterministic jitter is the difference between the source jitter at point A and the load jitter at point B in
Figure 2. The deterministic jitter (DJ) at the output of the transmission line must be from media-induced loss and not from
clock-source modulation. Depending upon the system environment, better results can be achieved by selecting different
preemphasis levels.
Valid with pattern generator deterministic jitter as high as 0.17UIP-P.
_______________________________________________________________________________________
5
MAX3983
ELECTRICAL CHARACTERISTICS (continued)
MAX3983
Quad Copper-Cable Signal Conditioner
PE = 12dB
PE = 3dB
DIFFERENTIAL
VEYE = 0.375VP-P OUTPUT = 1.5V
P-P
VEYE = 1.06VP-P
Figure 1. Illustration of TX Preemphasis in dB
END-TO-END TESTING
PC BOARD (FR4)
A
SIGNAL
SOURCE
InfiniBand CABLE
ASSEMBLY
MAX3983
6 mils
TX_IN
TX_OUT
1in ≤ L ≤ 20in
6 mils
1in ≤ L ≤ 3in
SMA CONNECTORS
1in ≤ L ≤ 20in
1in ≤ L ≤ 3in
FUJITSU
MICROGIGA
CONNECTORS
MAX3983
6 mils
OSCILLOSCOPE OR
ERROR DETECTOR
B
RX_OUT
RX_IN
6 mils
FR4
4.0 ≤ εR ≤ 4.4
tanδ = 0.022
Figure 2. End-to-End Test Setup. The points labeled A and B are referenced for AC parameter test conditions.
6
_______________________________________________________________________________________
Quad Copper-Cable Signal Conditioner
VERTICAL EYE OPENING
vs. CABLE LENGTH
3.125Gbps
K28.7 PATTERN
MEASURED DIRECTLY AT PART
A = 3dB, TX_PE = 00
B = 6dB, TX_PE = 01
C = 9dB, TX_PE = 10
D = 12dB, TX_PE = 11
10m 24AWG UNEQUALIZED CABLE
ASSEMBLY OUTPUT WITHOUT MAX3983
TX_PE[1,0] = 00
800
TX_PE[1,0] = 01
700
600
3.125Gbps
XAUI CJPAT
CABLE ONLY
250
DJ (ps)
TX_PE[1,0] = 10
500
TX_PE[1,0] = 11
400
300
D
2.5Gbps XAUI CJPAT
ALL CHANNELS TRANSMITTING
10in FR4 AT TX_IN
10in FR4 AT RX_OUT
SOURCE DJ = 23ps
200
150
A
E
100
B
C
200
C
50
2.5Gbps XAUI CJPAT
24AWG CABLE
100
D
A, B
0
0
0
5
10
20
15
0
CABLE LENGTH (m)
0
PREEMPHASIS,
TX_PE[1, 0] = 10
15
20
USING AGILENT 8720ES AND ATN MICROWAVE
ATN-4112A S-PARAMETER TEST SET
DE-EMBEDDING SMA CONNECTOR,
COUPLING CAPACITOR, AND 3in TRACE
-5
-10
320mVP-P
10
TX_IN INPUT RETURN LOSS
vs. FREQUENCY
MAX3983 toc05
3.125Gbps
XAUI CJPAT
5
CABLE LENGTH (m)
A = 24AWG, TX_PE[1,0] = 00 D = 24AWG, TX_PE[1,0] = 11
B = 24AWG, TX_PE[1,0] = 01 E = 28AWG, TX_PE[1,0] = 11
C = 24AWG, TX_PE[1,0] = 10
10m 24AWG UNEQUALIZED CABLE ASSEMBLY
OUTPUT WITH MAX3983 PREEMPHASIS
MAX3983 toc04
1500mVP-P
AT TRANSMITTER
300
MAX3983 toc06
D
C
B
A
VOUT
VERTICAL EYE OPENING (mVP-P)
B
C
D
350
MAX3983 toc02
1000
900
A
END-TO-END DETERMINISTIC JITTER
vs. CABLE LENGTH
DIFFERENTIAL S11 (dB)
MAX3983 toc01
MAX3983 toc03
TRANSIENT REPSONSE
-15
-20
-25
-30
-35
-40
-45
-50
60ps/div
60ps/div
0
0.4 0.8 1.2 1.6 2.0 2.4 2.8 3.2 3.6 4.0
FREQUENCY (GHz)
_______________________________________________________________________________________
7
MAX3983
Typical Operating Characteristics
(VCC = +3.3V, TA = +25°C, unless otherwise noted.)
Typical Operating Characteristics (continued)
(VCC = +3.3V, TA = +25°C, unless otherwise noted.)
DIFFERENTIAL S22 (dB)
-5
-10
0
-15
-20
-25
USING AGILENT 8720ES AND ATN MICROWAVE
ATN-4112A S-PARAMETER TEST SET
DE-EMBEDDING SMA CONNECTOR,
COUPLING CAPACITOR, AND 3in TRACE
-5
-10
DIFFERENTIAL S11 (dB)
USING AGILENT 8720ES AND ATN MICROWAVE
ATN-4112A S-PARAMETER TEST SET
DE-EMBEDDING SMA CONNECTOR,
COUPLING CAPACITOR, AND 3in TRACE
MAX3983 toc07
0
MAX3983 toc08
RX_IN INPUT RETURN LOSS
vs. FREQUENCY
TX_OUT OUTPUT RETURN LOSS
vs. FREQUENCY
-15
-20
-25
-30
-35
-40
-30
-45
-50
-35
FREQUENCY (GHz)
RX_OUT OUTPUT RETURN LOSS
vs. FREQUENCY
POWER-ON RESET DELAY
WITH SUPPLY RAMP
USING AGILENT 8720ES AND ATN MICROWAVE
ATN-4112A S-PARAMETER TEST SET
DE-EMBEDDING SMA CONNECTOR,
COUPLING CAPACITOR, AND 3in TRACE
-5
-10
0.4 0.8 1.2 1.6 2.0 2.4 2.8 3.2 3.6 4.0
FREQUENCY (GHz)
MAX3983 toc12
0
0
0.4 0.8 1.2 1.6 2.0 2.4 2.8 3.2 3.6 4.0
MAX3983 toc09
0
DIFFERENTIAL S22 (dB)
MAX3983
Quad Copper-Cable Signal Conditioner
1V/div
-15
VCC
-20
1µF CAPACITOR FROM
POR PIN TO GROUND
-25
200mA/div
-30
ICC
-35
-40
0
0.4 0.8 1.2 1.6 2.0 2.4 2.8 3.2 3.6 4.0
2ms/div
FREQUENCY (GHz)
8
_______________________________________________________________________________________
Quad Copper-Cable Signal Conditioner
PIN
NAME
1, 2, 16, 17
TX_SD1 to
TX_SD4
3, 15
VCC1
4, 7, 10, 13
TX_IN1- to
TX_IN4-
PC Board Receiver Negative Data Inputs, CML. These inputs are internally differentially terminated to
the corresponding TX_IN+ with 100Ω.
5, 8, 11, 14
TX_IN1+ to
TX_IN4+
PC Board Receiver Positive Data Inputs, CML. These inputs are internally differentially terminated to
the corresponding TX_IN- with 100Ω.
6, 9, 12, 40,
43, 46
GND
18
FUNCTION
PC Board Receiver Signal Detect, TTL Output. This output is open-collector TTL, and therefore
requires an external 4.7kΩ to 10kΩ pullup resistor to VCC. These outputs sink current when the input
signal level is not valid.
Power-Supply Connection for TX Inputs. Connect to +3.3V.
Circuit Ground
Cable Transmitter Enable Input, LVTTL with 40kΩ Internal Pullup. This pin enables all four cable
TX_ENABLE transmitter outputs TX_OUT[1:4]. When low, differential output is less than 30mVP-P. Set high or open
for normal operation.
19
N.C.
No Connection. Do not connect this pin.
20, 23, 26,
29, 32
VCC2
Power-Supply Connection for TX Outputs. Connect to +3.3V.
21, 24, 27,
30
TX_OUT1+ to
Cable Transmitter Positive Data Outputs, CML. These outputs are terminated with 50Ω to VCC2.
TX_OUT4+
22, 25, 28,
31
TX_OUT1- to
Cable Transmitter Negative Data Outputs, CML. These outputs are terminated with 50Ω to VCC2.
TX_OUT4-
33
TX_PE0
Cable Transmitter Preemphasis Control Input, LVTTL with 40kΩ Internal Pullup. This pin is the least
significant bit of the 2-bit preemphasis control. Set high or open to assert this bit.
34
TX_PE1
Cable Transmitter Preemphasis Control Input, LVTTL with 40kΩ Internal Pullup. This pin is the most
significant bit of the 2-bit preemphasis control. Set high or open to assert this bit.
35, 36, 50,
51
RX_SD4 to
RX_SD1
Cable Receiver Signal Detect, TTL Output. This output is open-collector TTL, and therefore it requires
an external 4.7kΩ to 10kΩ pullup resistor to VCC. These outputs sink current when the input signal
level is not valid.
37, 49
VCC3
38, 41, 44,
47
RX_IN4- to
RX_IN1-
Cable Receiver Negative Data Inputs, CML. These inputs are internally differentially terminated to the
corresponding RX_IN+ with 100Ω.
39, 42, 45,
48
RX_IN4+ to
RX_IN1+
Cable Receiver Positive Data Inputs, CML. These inputs are internally differentially terminated to the
corresponding RX_IN- with 100Ω.
52
Power-Supply Connection for RX Inputs. Connect to +3.3V.
PC Board Transmitter Enable Input, LVTTL with 40kΩ Internal Pullup. This pin enables all four PC
RX_ENABLE board transmitter outputs RX_OUT[1:4]. When low, differential output is less than 30mVP-P. Set high
or open for normal operation.
53
POR
Power-On Reset Connection. Connect external capacitor 0.1µF ≤ CPOR ≤ 10µF to ground. See the
Detailed Description.
54, 57, 60,
63, 66
VCC4
Power-Supply Connection for RX Outputs. Connect to +3.3V.
_______________________________________________________________________________________
9
MAX3983
Pin Description
MAX3983
Quad Copper-Cable Signal Conditioner
Pin Description (continued)
PIN
NAME
FUNCTION
55, 58, 61,
64
RX_OUT4+ to
PC Board Transmitter Positive Data Outputs, CML. These outputs are terminated with 50Ω to VCC4.
RX_OUT1+
56, 59, 62,
65
RX_OUT4- to
PC Board Transmitter Negative Data Outputs, CML. These outputs are terminated with 50Ω to VCC4.
RX_OUT1PC Board Transmitter Preemphasis Control Input, LVTTL with 40kΩ Internal Pullup. Set high or open
to assert this bit.
67
RX_PE
68
LOOPBACK
Loopback Enable Input, LVTTL with 40kΩ Internal Pullup. Set low for normal operation. Set high or
open for internal connection of TX_IN to RX_OUT. TX_OUT continues to transmit when loopback is
enabled.
EP
Exposed Pad
Exposed Pad. Signal and supply ground. For optimal high-frequency performance and thermal
conductivity, this pad must be soldered to the circuit board ground.
VCC1
40kΩ
VCC2
2
LVTTL
TX_PE[0:1]
VCC2
VCC1
LIMITER
TX_IN[1:4]+
FIXED
EQUALIZER
CML
TX_IN[1:4]-
CML
TX_OUT[1:4]-
VCC1
VCC1
VCC2
TX_SD[1:4]
SIGNAL
DETECT
40kΩ
TX_ENABLE
TX_OUT[1:4]+
PREEMPHASIS
VCC2
LVTTL
VCC3
40kΩ
LOOPBACK
VCC4
POWER
MANAGEMENT
VCC4
VCC4
VCC3
1
RX_OUT[1:4]+
RX_OUT[1:4]-
PREEMPHASIS
CML
VCC3
RX_SD[1:4]
RX_IN[1:4]+
CML
LIMITER
VCC4
LVTTL
40kΩ
RX_PE
FIXED
EQUALIZER
0
VCC3
40kΩ
RX_ENABLE
VCC4
MAX3983
LVTTL
VCC4
VCC3
SIGNAL
DETECT
GND
Figure 3. Functional Diagram
10
POR
LVTTL
______________________________________________________________________________________
RX_IN[1:4]-
Quad Copper-Cable Signal Conditioner
The MAX3983 comprises a PC board receiver and
cable driver section (TX), as well as a cable receiver
and PC board driver section (RX). Equalization and signal detection are provided in each receiver, and preemphasis is included in each transmitter. The MAX3983
includes separate enable control for the TX outputs and
RX outputs. Loopback is provided for diagnostic testing.
PC Board Receiver and Cable Driver
(TX_IN and TX_OUT)
Data is fed into the MAX3983 from the host through a
CML input stage and fixed equalization stage. The
fixed equalizer in the PC board receiver corrects for up
to 20in of PC board loss on FR4 material. The cable driver includes four-state preemphasis to compensate for
up to 20m of 24AWG, 100Ω balanced cable. Table 1 is
provided for easy translation between preemphasis
expressions. Residual jitter of the MAX3983 is independent of up to 0.17UIP-P source jitter.
Cable Receiver and PC Board Driver
(RX_IN and RX_OUT)
The fixed equalizer on each RX input provides approximately 6dB equalization to correct for up to 5m of
28AWG, 100Ω balanced cable. The PC board driver
includes two-state preemphasis to compensate for up
to 20in of FR4 material.
Signal-Detect Outputs
Signal detect (SD) is provided on all eight data inputs.
Pullup resistors should be connected from the SD outputs to a supply in the 3.0V to 5.5V range. The signaldetect outputs are not valid until power-up is complete.
Typical signal-detect response time is 0.35µs.
In the RX section, the SD output asserts high when the
RX_IN signal amplitude is greater than 175mV P-P .
RX_SD deasserts low when the RX_IN signal amplitude
drops below 85mVP-P.
In the TX section, the SD output asserts high when the
TX_IN signal amplitude is greater than 800mV P-P .
TX_SD deasserts low when the TX_IN signal amplitude
drops below 200mVP-P.
TX and RX Enable
The TX_ENABLE and RX_ENABLE pins enable TX and
RX, respectively. Typical enable time is 15ns, and typical disable time is 25ns. The enable inputs may be
connected to signal-detect outputs to automatically
detect an incoming signal (see the Autodetect section).
Power-On Reset
To limit inrush current, the MAX3983 includes internal
power-on reset circuitry. Connect a capacitor 0.1µF ≤
CPOR ≤ 10µF from POR to ground. With CPOR = 1µF,
power-on delay is 6ms (typ).
Table 1. Preemphasis Translation
RATIO
α
VHIGH _ PP
VHIGH _ PP − VLOW _ PP
VLOW _ PP
VHIGH _ PP + VLOW _ PP
1.41
0.17
0.29
3
2.00
0.33
0.50
6
2.82
0.48
0.65
9
4.00
0.60
0.75
12
10Gbase-CX4
1−
VLOW _ PP
VHIGH _ PP
IN dB
  VHIGH _ PP  
20log

  VLOW _ PP  
VHIGH_PP
VLOW_PP
______________________________________________________________________________________
11
MAX3983
Detailed Description
MAX3983
Quad Copper-Cable Signal Conditioner
Applications Information
Signal-Detect Output Leakage Current
Considerations
If all four RX or TX signal-detect outputs are to be connected together to form one signal detect, the leakage
current of the output stage needs to be considered.
Each SD output sinks a maximum of 25µA when asserted, so when four are connected together, a maximum of
100µA is possible. The value of the pullup resistor connected to pullup voltage VPULLUP should be selected so
the leakage current does not cause the output voltage to
fall below the threshold of the next stage. For example, if
the signal-detect outputs are connected together and to
a stage with a logic-high threshold of 1.5V, the pullup
resistor needs to be chosen so VPULLUP - ILEAKAGE x
R PULLUP > 1.5V. In this case, if V PULLUP = 3.0V,
RPULLUP should be less than 15kΩ.
Autodetect
The MAX3983 can automatically detect an incoming signal and enable the appropriate outputs. Autodetect of
the RX side is done by connecting RX_SD[1:4] together
with a pullup resistor (value 4.7kΩ to 10kΩ to VCC) to
RX_ENABLE. For the TX side, this is done by connecting
TX_SD[1:4] together with a pullup resistor (value 4.7kΩ
to 10kΩ to VCC) to TX_ENABLE (Figure 4). If signal is
detected on all channels, SD is high and forces the corresponding ENABLE high. Leaving the inputs to the
MAX3983 open (i.e., floating) is not recommended, as
noise amplification can occur and create undesirable
output signals. Autodetect is recommended to eliminate
noise amplification or possible oscillation. When using
autodetect, the link length is determined by the received
signal strength. It is possible to reach longer distances if
the autodetect configuration is not used.
Using Loopback with Autodetect
If the MAX3983 is configured for autodetection,
RX_ENABLE is controlled by the RX_SD[1:4] outputs.
Since loopback requires RX_ENABLE to be high, a simple OR gate can be used to enable the RX outputs
when either RX_SD[1:4] is high or when LOOPBACK is
high (Figure 5).
InfiniBand and 10Gbase-CX4 Transition
Time Specification
InfiniBand specifies a minimum transition time (20% to
80%) of 100ps and CX4 specifies a minimum of 60ps.
Both are specified at the connector interface to the
cable. The output transition times of the MAX3983 are
45ps (typ) and therefore require some care to increase
this time. Approximately 3in of FR4 with 4-mil-wide lines
is sufficient to lengthen the transition time to 60ps. For
100ps transition times, additional length can be used or
an additional 1.5pF capacitor can be placed across the
outputs of the MAX3983. Do not use high-speed dielectric material for the circuit board if the application
requires the use of the InfiniBand or CX4 type connector
system. With such materials, the fast edges of the
3.0V ≤ VPULLUP ≤ 5.5V
3.0V ≤ VPULLUP ≤ 5.5V
4.7kΩ ≤ R ≤ 10kΩ
4.7kΩ ≤ R ≤ 10kΩ
RX OR TX_SD1
MAX3983
RX OR TX_SD2
RX OR TX_SD3
RX OR TX_SD4
RX_SD1
MAX3983
RX_SD2
RX_SD3
RX_SD4
RX_ENABLE
RX OR TX_ENABLE
LOOPBACK
TO HOST
Figure 4. Autodetection Using Corresponding Signal-Detect
Outputs and Enable Input
12
Figure 5. Loopback in Autodetect Mode
______________________________________________________________________________________
Quad Copper-Cable Signal Conditioner
Crosstalk
For InfiniBand and 10Gbase-CX4 applications, it is
imperative to know the near-end crosstalk characteristics
of the cable assemblies. 10Gbase-CX4 has defined the
upper limit over frequency for near-end crosstalk (NEXT)
with single and multiple aggressors. InfiniBand has only
specified a percentage as measured in the time domain
relative to the transmitter output. Regardless of the specification method, NEXT is a critical component of the link
performance. When using larger amounts of preemphasis, the received eye height is small and vulnerable to
NEXT. For those situations requiring a large transmit preemphasis, the NEXT should be less than -30dB at frequencies from 1GHz to 3GHz. It should be noted that
cables that meet the 10Gbase-CX4 NEXT and MDNEXT
should provide adequate isolation.
Layout Considerations
Circuit board layout and design can significantly affect
the performance of the MAX3983. Use good high-frequency design techniques, including minimizing
ground inductance and using controlled-impedance
transmission lines on the data signals. Power-supply
decoupling should also be placed as close to the VCC
pins as possible. There should be sufficient supply filtering. Always connect all VCCs to a power plane. Take
care to isolate the input from the output signals to
reduce feedthrough. The performance of the equalizer
is optimized for lossy environments. For best results,
use board material with a dielectric tangential loss of
approximately 0.02 and 4-mil-wide transmission lines.
High-speed materials with tangential loss of less than
0.01 can be used, but require special care to reduce
near-end crosstalk in cable assemblies.
VCCX
5pF
RX_IN[1:4]+
TX_IN[1:4]+
50Ω
VCCX - 1.5V
50Ω
RX_IN[1:4]TX_IN[1:4]-
GND
Figure 6. RX_IN and TX_IN Equivalent Input Structure
VCCX
50Ω
50Ω
Exposed-Pad Package
The exposed-pad, 68-pin QFN package incorporates
features that provide a very low thermal resistance path
for heat removal from the IC. The pad is electrical
ground on the MAX3983 and must be soldered to the
circuit board for proper thermal and electrical performance. For more information on exposed-pad packages, refer to Maxim Application Note HFAN-08.1:
Thermal Considerations of QFN and Other ExposedPaddle Packages.
RX_OUT[1:4]+
TX_OUT[1:4]+
RX_OUT[1:4]TX_OUT[1:4]-
GND
Figure 7. RX_OUT and TX_OUT Equivalent Output Structure
______________________________________________________________________________________
13
MAX3983
Interface Schematics
MAX3983 will produce excessive crosstalk in InfiniBand
and CX4 cable assemblies.
MAX3983
Quad Copper-Cable Signal Conditioner
VCCY
VCCX
RX_SD[1:4]
TX_SD[1:4]
40kΩ
LVTTL IN
GND
PIN NAME
VCCX
VCCY
RX_ENABLE,
LOOPBACK, RX_PE
VCC3
VCC4
TX_ENABLE,
TXPE[0:1]
VCC1
VCC2
Figure 8. LVTTL Equivalent Input Structure
14
GND
Figure 9. Signal-Detect Equivalent Output Structure
______________________________________________________________________________________
Quad Copper-Cable Signal Conditioner
58
57
56
RX_ENABLE
59
POR
60
RX_OUT4+
61
VCC4
RX_OUT4-
62
VCC4
63
RX_OUT3+
64
RX_OUT3-
RX_OUT2-
65
RX_OUT2+
VCC4
66
VCC4
RX_OUT1+
67
VCC4
RX_PE
68
RX_OUT1-
LOOPBACK
TOP VIEW
55
54
53
52
TX_SD1
1
51 RX_SD1
TX_SD2
2
50 RX_SD2
VCC1
3
49 VCC3
TX_IN1-
4
48 RX_IN1+
TX_IN1+
5
47 RX_IN1-
GND
6
46 GND
TX_IN2-
7
45 RX_IN2+
TX_IN2+
8
44 RX_IN2-
GND
9
TX_IN3-
10
TX_IN3+
11
41 RX_IN3-
43 GND
MAX3983
42 RX_IN3+
22
23
24
25
26
27
28
29
30
31
32
33
34
TX_PE1
21
TX_PE0
20
VCC2
19
TX_OUT2-
TX_ENABLE
18
TX_OUT4-
35 RX_SD4
VCC2
36 RX_SD3
17
TX_OUT4+
16
TX_SD4
TX_OUT3-
TX_SD3
VCC2
37 VCC3
TX_OUT3+
38 RX_IN4-
15
TX_OUT2+
14
VCC1
VCC2
TX_IN4+
TX_OUT1-
39 RX_IN4+
TX_OUT1+
40 GND
13
N.C.
12
VCC2
GND
TX_IN4-
68 QFN*
*THE EXPOSED PAD OF THE QFN PACKAGE MUST BE SOLDERED TO GROUND
FOR PROPER THERMAL AND ELECTRICAL OPERATION OF THE MAX3983.
Chip Information
TRANSISTOR COUNT: 7493
PROCESS: SiGe Bipolar
______________________________________________________________________________________
15
MAX3983
Pin Configuration
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
68L QFN.EPS
MAX3983
Quad Copper-Cable Signal Conditioner
PACKAGE OUTLINE, 68L QFN, 10x10x0.9 MM
1
C
21-0122
2
PACKAGE OUTLINE, 68L QFN, 10x10x0.9 MM
1
C
21-0122
2
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
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Printed USA
is a registered trademark of Maxim Integrated Products.