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19-3354; Rev 0; 8/04
SFP Copper-Cable Preemphasis Driver
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 0C to +85C temperature range. Drives Up to 15m with 24AWG Cable Drives Up to 30in of FR4 0.25W Total Power with +3.3V Supply Selectable 1600mVP-P or 1200mVP-P Differential Output Swing Selectable Output Preemphasis Fixed Input Equalization Loss-of-Signal Detection with Selectable Sensitivity Transmit Disable
Features
MAX3982
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
Ordering Information
PART MAX3982UTE TEMP RANGE 0C to +85C PINPACKAGE 16 Thin QFN PKG CODE T1633-4
Pin Configuration appears at end of data sheet.
Typical Application Circuit
DISK ENCLOSURE +3.3V V TX_DISABLE CC PE0 PE1 LOSLEV MAX3982 OUTLEV 0.01F IN+ INGND OUT+ OUT 15m (24AWG) UP TO 4.25Gbps LOS COPPER-CABLE DIFFERENTIAL 100 TWIN-AX 0.01F 0.01F IN+ INGND SFP ACTIVE CABLE ASSEMBLY +3.3V VCC LOS FABRIC SWITCH 5V 4.7k
VCC OR GND SWITCH OR SERDES TX+ TX0.01F
4.25Gbps LIMITING AMPLIFIER
OUT+ OUT0.01F
0.01F
SWITCH OR SERDES RX+ RX-
+3.3V 0.01F RX+ RX 5V 4.7k LOS GND 0.01F OUT+ OUTVCC IN+ IN0.01F 0.01F OUT+ OUT-
+3.3V 0.01F VCC IN+ IN0.01F TX+ TXVCC OR GND
4.25Gbps LIMITING AMPLIFIER
MAX3982
LOS
PE0 PE1 LOSLEV
GND
OUTLEV TX_DISABLE
________________________________________________________________ Maxim Integrated Products
1
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.
SFP Copper-Cable Preemphasis Driver MAX3982
ABSOLUTE MAXIMUM RATINGS
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 (VCC + 0.5V) LOS Open Collector Supply Voltage with 4.7k Pullup Resistor..............................-0.5V to +5.5V Continuous Power Dissipation at +85C (derate 20.8mW/C above +85C) .................................1.35W Operating Junction Temperature Range (TJ) ....-55C to +150C Storage Ambient Temperature Range (TS) .......-55C to +150C
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 = 0C to +85C. Typical values are at TA = +25C and VCC = +3.3V, unless otherwise noted.)
PARAMETER Supply Current Inrush Current Power-On-Reset Delay OPERATING CONDITIONS Supply Voltage Supply-Noise Tolerance Operating Ambient Temperature Bit Rate CID Voltage, Logic High Voltage, Logic Low Current, Logic High Current, Logic Low STATUS OUTPUT: LOS LOS asserted LOS Open Collector Current Sink LOS unasserted, VOL 0.4V with 4.7k pullup resistor, pullup supply = 5.5V VCC = 0V, pullup supply = 5.5V, external pullup resistor 4.7k LOS Assert Level LOS Deassert Level LOS Hysteresis LOSLEV = high (Note 1) LOSLEV = low (Note 1) LOSLEV = high (Note 1) LOSLEV = low (Note 1) LOSLEV = high (Note 1) LOSLEV = low (Note 1) Time from IN dropping below assert level, or rising above deassert level to 50% point of LOS Rise-time or fall-time (10% to 90%), external pullup resistor = 4.7k 250 20 4 10 0 1.0 0 100 50 300 120 25 25 A mA A mVP-P mVP-P mVP-P mVP-P mVP-P mVP-P s VIH VIL IIH IIL VIH = VCC + 0.5V VIL = 0.8V TA NRZ data (Note 1) Consecutive identical digits (bits) (Note 1) 2.0 0.8 -150 350 VCC 1MHz f < 2GHz 0 1.0 3.0 3.3 40 25 85 4.25 10 3.6 V mVP-P C Gbps Bits V V A A tPOR SYMBOL CONDITIONS TX_DISABLE=low Current beyond steady-state current 1 MIN TYP 75 MAX 97 10 40 UNITS mA mA ms
CONTROL INPUTS: TX_DISABLE, PE0, PE1, OUTLEV, LOSLEV
LOS Response Time
LOS Transition Time
ns
2
_______________________________________________________________________________________
SFP Copper-Cable Preemphasis Driver
ELECTRICAL CHARACTERISTICS (continued)
(VCC = +3.0V to +3.6V, TA = 0C to +85C. Typical values are at TA = +25C and VCC = +3.3V, unless otherwise noted.)
PARAMETER SYMBOL CONDITIONS Measured differentially at point A of Figure 2 (Note 1) Measured differentially 100MHz to 2GHz (Note 1) Measured differentially at point B of Figure 2 (Notes 1, 2) TX_DISABLE = low, OUTLEV = high TX_DISABLE = low, OUTLEV = low TX_DISABLE = high Common-Mode Output Output Resistance Output Return Loss Output Transition Time Random Jitter tr, tf (OUT+) + (OUT-), measured at point B of Figure 2; TX_DISABLE = low, OUTLEV = high (Notes 1, 2) OUT+ or OUT- to VCC, single ended 100MHz to 2GHz (Note 1) 20% to 80% (Notes 1, 3) (Notes 1, 3) PE1 0 Output Preemphasis See Figure 1 0 1 1 Source to IN Residual Output Deterministic Jitter at 1.0625Gbps to 2.125Gbps (Notes 1, 4, 5) 6 mil FR4 10in Source to IN Residual Output Deterministic Jitter at 4.25Gbps (Notes 1, 4, 5) 6 mil FR4 10in OUT to Load 1m, 24AWG 5m, 24AWG 10m, 24AWG 15m, 24AWG OUT to Load 1m, 24AWG 5m, 24AWG 10m, 24AWG 15m, 24AWG PE1 0 0 1 1 PE1 0 0 1 1 PE0 0 1 0 1 PE0 0 1 0 1 PE0 0 1 0 1 0.15 0.20 UIP-P 0.10 0.15 UIP-P 2 4 8 14 dB 42 10 50 80 1.6 50 MIN TYP MAX UNITS
MAX3982
EQUALIZER AND CABLE DRIVER SPECIFICATIONS Input Swing Input Resistance Input Return Loss 600 85 10 1450 1000 40 60 58 mVP-P dB ps psRMS 1800 1350 mVP-P 100 2000 115 mVP-P dB
Differential Output Swing
Note 1: Guaranteed by design and characterization. Note 2: PE1 = PE0 = 1 for maximum preemphasis, load is 50 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. _______________________________________________________________________________________ 3
SFP Copper-Cable Preemphasis Driver MAX3982
VLOW_PP VHIGH_PP
V HIGH _ PP PE(dB) = 20 log VLOW _ PP
Figure 1. Illustration of Tx Preemphasis in dB
TEST SETUP PCBOARD (FR4) SIGNAL SOURCE A B
MAX3982
6 mil IN OUT 6 mil
24AWG 100 TWIN-AX
1in L 10in SMA CONNECTORS OSCILLOSCOPE OR ERROR DETECTOR
L = 2in SMA CONNECTORS
L 1in
6 mil FR4 4.0 R 4.4 tan = 0.022
D
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.
4
_______________________________________________________________________________________
SFP Copper-Cable Preemphasis Driver MAX3982
TEST SETUP PC BOARD (FR4) SIGNAL SOURCE A B
MAX3982
6 mil IN OUT 6 mil
24AWG 100 TWIN-AX
1in L 12in SMA CONNECTORS OSCILLOSCOPE OR ERROR DETECTOR L 1in
L = 2in L 1in 39 22pF SMA CONNECTORS
MAX3748
6 mil IN OUT
D
FR4 4.0 R 4.4 tan = 0.022
22pF 39
Figure 3. End-to-End Test Setup Using the MAX3748 as a Receiver. Deterministic jitter and eye diagrams measured at point D.
Typical Operating Characteristics
(VCC = +3.3V, TA = +25C, unless otherwise noted. PRBS7 + 100CID pattern is PRBS 27, 100 zeros, 1010, PRBS 27, 100 ones, 0101.)
END-TO-END DETERMINISTIC JITTER vs. CABLE LENGTH AT 4.25Gbps
MAX3982 toc02
TRANSIENT RESPONSE
MAX3982 toc01
END-TO-END DETERMINISTIC JITTER vs. CABLE LENGTH AT 2.125Gbps
2.125Gbps PRBS7 + 100CID 12in FR4 AT INPUT USING MAX3748 AS RECEIVER, AS SHOWN IN FIGURE 3 PE[1,0] = 00 PE[1,0] = 01 PE[1,0] = 10 PE[1,0] = 11 0.9 DETERMINISTIC JITTER (UI) 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0
MAX3982 toc03
4.25Gbps K28.7 PATTERN OUTLEV = HIGH DETERMINISTIC JITTER (UI) A B C D D C B A
1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1
4.25Gbps PRBS7 + 100CID
1.0
PE[1,0] = 00
PE[1,0] = 01 12in FR4 AT INPUT USING MAX3748 AS RECEIVER, AS SHOWN IN FIGURE 3 PE[1,0] = 10 PE[1,0] = 11
A = 2dB, PE = 00 B = 4dB, PE = 01
C = 8dB, PE = 10 D = 14dB, PE = 11
0 0 5 10 CABLE LENGTH (m) 15 20
0
5
10 CABLE LENGTH (m)
15
20
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SFP Copper-Cable Preemphasis Driver MAX3982
Typical Operating Characteristics (continued)
(VCC = +3.3V, TA = +25C, unless otherwise noted. PRBS7 + 100CID pattern is PRBS 27, 100 zeros, 1010, PRBS 27, 100 ones, 0101.)
END-TO-END EYE DIAGRAM, 20m 24AWG CABLE AT 4.25Gbps
MAX3982 toc04
END-TO-END EYE DIAGRAM, 20m 24AWG CABLE AT 2.125Gbps
MAX3982 toc05
END-TO-END EYE DIAGRAM, 20m 24AWG CABLE AT 1.0625Gbps
MAX3982 toc06
4.25Gbps PRBS7 + 100CID PATTERN, 0in FR4 AT INPUT, USING MAX3748 AS RECEIVER, AS SHOWN IN FIGURE 3
2.125Gbps PRBS7 + 100CID PATTERN, 0in FR4 AT INPUT, USING MAX3748 AS RECEIVER, AS SHOWN IN FIGURE 3
1.0625Gbps PRBS7 + 100CID PATTERN, 0in FR4 AT INPUT, USING MAX3748 AS RECEIVER, AS SHOWN IN FIGURE 3
END-TO-END DETERMINISTIC JITTER vs. CABLE LENGTH AT 1.0625Gbps
1.0625Gbps PRBS7 + 100CID 12in FR4 AT INPUT USING MAX3748 AS RECEIVER, AS SHOWN IN FIGURE 3 PE[1,0] = 00 PE[1,0] = 01 PE[1,0] = 10 PE[1,0] = 11 0.45 DETERMINISTIC JITTER (UI) 0.40 0.35 0.30 0.25 0.20 0.15 0.10 0.05 0 0 5 10 CABLE LENGTH (m) 15 20 0
MAX3982 toc07
VERTICAL EYE OPENING vs. CABLE LENGTH WITH OUTLEV = LOW
PE[1,0] = 00
MAX3982 toc08
0.50
700 VERTICAL EYE OPENING (mVP-P) 600 500 PE[1,0] = 01 400 PE[1,0] = 10 300 200 100 4.25Gbps PRBS7 + 100CID 0 5 10 PE[1,0] = 11
15
CABLE LENGTH (m)
VERTICAL EYE OPENING vs. CABLE LENGTH WITH OUTLEV = LOW
MAX3982 toc09
INPUT RETURN LOSS vs. FREQUENCY
-5 DIFFERENTIAL S11 (dB) -10 -15 -20 -25 -30 -35 USING AGILENT 8720ES AND ATN MICROWAVE ATN-4112A S-PARAMETER TEST SET DE-EMBEDDING SMA CONNECTOR, COUPLING CAPACITOR, AND 1cm TRACE
MAX3982 toc10
700 PE[1,0] = 00 VERTICAL EYE OPENING (mVP-P) 600 500 400 300 PE[1,0] = 11 200 100 0 0 4.25Gbps PRBS7 + 100CID 5 10 PE[1,0] = 01
0
PE[1,0] = 10
-40 15 100 1000 FREQUENCY (MHz) 10,000
CABLE LENGTH (m)
6
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SFP Copper-Cable Preemphasis Driver MAX3982
Typical Operating Characteristics (continued)
(VCC = +3.3V, TA = +25C, unless otherwise noted. PRBS7 + 100CID pattern is PRBS 27, 100 zeros, 1010, PRBS 27, 100 ones, 0101.)
15m 24AWG CABLE ASSEMBLY OUTPUT WITHOUT MAX3982, 4.25Gbps CJTPAT
MAX3982 toc11
15m 24AWG CABLE ASSEMBLY OUTPUT WITH MAX3982 PREEMPHASIS, 4.25Gbps CJTPAT
MAX3982 toc12
DETERMINISTIC JITTER vs. CABLE LENGTH
4.25Gbps PRBS7 + 100CID DETERMINISTIC JITTER (UI) 0.8 PE[1,0] = 00 PE[1,0] = 01 PE[1,0] = 10
MAX3982 toc13
1.0
40mV/div
0.6
0.4
PE[1,0] = 11
0.2 PREEMPHASIS, PE[1,0] = 11, OUTLEV = HIGH
0 0 5 10 15 CABLE LENGTH (m)
15m 24AWG CABLE ASSEMBLY OUTPUT WITHOUT MAX3982, 4.25Gbps PRBS7 + 100CID
MAX3982 toc14
15m 24AWG CABLE ASSEMBLY OUTPUT WITH MAX3982 PREEMPHASIS, 4.25Gbps PRBS7 + 100CID
MAX3982 toc15
OUTPUT RETURN LOSS vs. FREQUENCY
-5 DIFFERENTIAL S22 (dB) -10 -15 -20 -25 -30 -35 USING AGILENT 8720ES AND ATN MICROWAVE ATN-4112A S-PARAMETER TEST SET DE-EMBEDDING SMA CONNECTOR, COUPLING CAPACITOR, AND 1cm TRACE
MAX3982 toc16
0
40mV/div PREEMPHASIS, PE[1,0] = 11, OUTLEV = HIGH
-40 100 1000 FREQUENCY (MHz) 10,000
_______________________________________________________________________________________
7
SFP Copper-Cable Preemphasis Driver MAX3982
Typical Operating Characteristics (continued)
(VCC = +3.3V, TA = +25C, unless otherwise noted. PRBS7 + 100CID pattern is PRBS 27, 100 zeros, 1010, PRBS 27, 100 ones, 0101.)
15m 24AWG CABLE ASSEMBLY OUTPUT WITHOUT MAX3982, 4.25Gbps PRBS31
MAX3982 toc17
15m 24AWG CABLE ASSEMBLY OUTPUT WITH MAX3982 PREEMPHASIS, 4.25Gbps PRBS31
MAX3982 toc18
HOT-PLUG WITH TX_DISABLE LOW
MAX3982 toc19
3.3V VCC
0V LOW tPOR = 27ms
40mV/div
TX_DISABLE
OUT+ PREEMPHASIS, PE[1,0] = 11, OUTLEV = HIGH 10ms/div
30in FR4 OUTPUT WITHOUT MAX3982, 4.25Gbps CJTPAT
MAX3982 toc20
30in FR4 OUTPUT WITH MAX3982 PREEMPHASIS, 4.25Gbps CJTPAT
MAX3982 toc21
DETERMINISTIC JITTER vs. FR4 LENGTH
4.25Gbps PRBS7 DRIVING FR4 AT OUT+ AND OUT-, NO FR4 AT INPUT PE[1,0] = 00
MAX3982 toc22
1.2 1.0 DETERMINISTIC JITTER (UI) 0.8
100mV/div
PE[1,0] = 01 0.6 0.4 0.2 0 0 10 20 30 40 50 FR4 LENGTH (in)
PE[1,0] = 11 PE[1,0] = 10
PREEMPHASIS, PE[1,0] = 10, OUTLEV = HIGH
8
_______________________________________________________________________________________
SFP Copper-Cable Preemphasis Driver MAX3982
Typical Operating Characteristics (continued)
(VCC = +3.3V, TA = +25C, unless otherwise noted. PRBS7 + 100CID pattern is PRBS 27, 100 zeros, 1010, PRBS 27, 100 ones, 0101.)
30in FR4 OUTPUT WITHOUT MAX3982 4.25Gbps PRBS7 + 100CID
MAX3982 toc23
30in FR4 OUTPUT WITH MAX3982 PREEMPHASIS, 4.25Gbps PRBS7 + 100CID
MAX3982 toc24
TRANSMITTER ENABLE
MAX3982 toc25
VCC
3.3V HIGH
100mV/div
TX_DISABLE
LOW
OUT+ PREEMPHASIS, PE[1,0] = 10, OUTLEV = HIGH 200ns/div
30in FR4 OUTPUT WITHOUT MAX3982, 4.25Gbps PRBS31
MAX3982 toc26
30in FR4 OUTPUT WITH MAX3982 PREEMPHASIS, 4.25Gbps PRBS31
MAX3982 toc27
TRANSMITTER DISABLE
MAX3982 toc28
VCC 3.3V HIGH 100mV/div TX_DISABLE LOW
OUT+ PREEMPHASIS, PE[1,0] = 10, OUTLEV = HIGH 200ns/div
_______________________________________________________________________________________
9
SFP Copper-Cable Preemphasis Driver MAX3982
Pin Description
PIN 1 2 3 4, 8, 9 5 6 7 10 11 12, 13 14 NAME VCC1 IN+ INGND OUTLEV PE1 PE0 OUTOUT+ VCC2 TX_DISABLE FUNCTION Power-Supply Connection for Input. Connect to +3.3V. Positive Data Input, CML. This input is internally terminated with 50 to VCC1. Negative Data Input, CML. This input is internally terminated with 50 to VCC1. Circuit Ground Output-Swing Control Input, LVTTL with 40k Internal Pullup. Set to TTL high or open for maximum output swing, or set to TTL low for reduced swing. Output Preemphasis Control Input, LVTTL with 10k Internal Pullup. This pin is the most significant bit of the 2-bit preemphasis control. Set high or open to assert this bit. Output Preemphasis Control Input, LVTTL with 10k Internal Pullup. This pin is the least significant bit of the 2-bit preemphasis control. Set high or open to assert this bit. Negative Data Output, CML. This output is terminated with 50 to VCC2. Positive Data Output, CML. This output is terminated with 50 to VCC2. Power-Supply Connection for Output. Connect to +3.3V. Transmitter Disable Input, LVTTL with 10k Internal Pullup. When high or open, differential output is 40mVP-P. Set low for normal operation. Loss-of-Signal Detect, TTL Output. This output is open-collector TTL, and therefore requires an external 4.7k to 10k pullup resistor (5.5V maximum). This output sinks current when the input signal level is valid. LOS Sensitivity Control Input, LVTTL with 40k Internal Pullup. Set to TTL high or open for less sensitivity (higher assert threshold). Set to TTL low for more sensitivity (lower assert threshold). Exposed Pad. For optimal thermal conductivity, this pad must be soldered to the circuit board ground.
15
LOS
16 EP
LOSLEV EXPOSED PAD
Pin Configuration
TOP VIEW LOSLEV LOS TX_DISABLE 14
16 VCC1 IN+ INGND 1 2 3 4
15
VCC2 13 12 VCC2 OUT+ OUTGND 11 10
MAX3982UTE
EXPOSED PAD* 5 OUTLEV 6 PE1 7 PE0 8 GND
9
THIN QFN *THE EXPOSED PAD OF THE QFN PACKAGE MUST BE SOLDERED TO GROUND FOR PROPER THERMAL OPERATION OF THE MAX3982.
10
______________________________________________________________________________________
SFP Copper-Cable Preemphasis Driver MAX3982
VCC2 VCC2 LVTTL
10k PE0 PE1 VCC1 IN+ 2
MAX3982
2 VCC2
LIMITER CML FIXED EQUALIZER PREEMPHASIS CML
OUT+ OUTLOS
IN-
VCC1 40k LOSLEV VCC2 10k TX_DISABLE VCC2 40k OUTLEV LVTTL VCC2 LVTTL VCC2 LVTTL VCC1
SIGNAL DETECT
GND
Figure 4. Functional Diagram
Detailed Description
The MAX3982 comprises a PC board receiver, a cable driver, and a loss-of-signal detector with adjustable threshold (Figure 4). Equalization is provided in the receiver. Selectable preemphasis and selectable output amplitude are included in the transmitter. The MAX3982 also includes transmit disable control for the output.
1600mVP-P. Residual jitter of the MAX3982 is independent of up to 0.20UIP-P source jitter.
Loss-of-Signal (LOS) Output
Loss-of-signal detection is provided on the data input. Pullup resistors should be connected from LOS to a supply in the range of +3.0V to +5.5V. The LOS output is not valid until power-up is complete. Typical LOS response time is 100ns. The LOS assert and deassert levels are set by the LOSLEV pin. When LOSLEV is LVTTL high or open, the LOS assert threshold is 180mV P-P. When LOSLEV is LVTTL low, the LOS assert threshold is 85mVP-P.
PC Board Receiver and Cable Driver
Data is fed into the MAX3982 through a CML input stage and fixed equalization stage. The fixed equalizer in the receiver corrects for up to 10in of PC board loss on FR4 material at 4.25Gbps. The cable driver includes four-state preemphasis to compensate for up to 15m of 24AWG, 100 balanced cable. Table 1 is provided for easy translation between preemphasis expressions. The OUTLEV pin selects the output amplitude. When OUTLEV is low, the amplitude is 1200mVP-P. When OUTLEV is high, the amplitude is
TX Disable
Transmit disable is provided to turn off the output when desired. The TX_DISABLE pin can be connected to LOS to automatically squelch the output when the incoming signal is below the threshold set by LOSLEV (see the Autodetect section).
11
______________________________________________________________________________________
SFP Copper-Cable Preemphasis Driver MAX3982
Table 1. Preemphasis Translation
Ratio 10Gbase-CX4 IN dB
VHIGH _ PP VLOW _ PP
1.26 1.58 2.51 5.01
VHIGH _ PP - VLOW _ PP VHIGH _ PP + VLOW _ PP
0.11 0.23 0.43 0.67
1-
VLOW _ PP VHIGH _ PP
0.21 0.37 0.6 0.8
V HIGH _ PP 20 log VLOW _ PP
2 4 8 14
VLOW_PP VHIGH_PP
Applications Information
Autodetect
The MAX3982 can automatically detect an incoming signal and enable the data outputs. Autodetect can be accomplished by connecting the LOS pin to TX_DISABLE. TX_DISABLE has a 10k internal pullup resistor. If a loss-of-signal is detected, the TX_DISABLE pin is forced high and disables the outputs. Leaving the inputs to the MAX3982 open (i.e., floating) is not recommended as noise amplification may occur and create undesirable output signals. Autodetect is recommended to eliminate noise amplification or possible oscillation. For periods much greater than 100ns without data transitions, autodetect disables the output.
Layout Considerations
Circuit board layout and design can significantly affect the performance of the MAX3982. 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. This should be sufficient supply filtering. Always connect all VCC pins to a power plane. Take care to isolate the input from the output signals to reduce feedthrough.
Exposed Pad Package
The exposed-pad, 16-pin QFN package incorporates features that provide a very low thermal resistance path for heat removal from the IC. The exposed pad on the MAX3982 must be soldered to the circuit board for proper thermal performance. For more information on exposed-pad packages, refer to Maxim Application Note HFAN-08.1: Thermal Considerations of QFN and Other Exposed-Paddle Packages.
Interface Schematics
VCC1 VCC2
50 IN+
50
50
50 OUT+ OUT-
IN-
GND
GND
Figure 5. IN+/IN- Equivalent Input Structure 12
Figure 6. OUT+/OUT- Equivalent Output Structure
______________________________________________________________________________________
SFP Copper-Cable Preemphasis Driver MAX3982
VCCX
LOS
RPULLUP
LVTTL IN
GND
Figure 8. Loss-of-Signal Equivalent Output Structure
GND PIN NAME LOSLEV OUTLEV VCCX RPULLUP (k) 40 VCC1 VCC2 40 10
Chip Information
TRANSISTOR COUNT: 2957 PROCESS: SiGe Bipolar
TX_DISABLE, PE0, PE1 VCC2
Figure 7. LVTTL Equivalent Input Structure
______________________________________________________________________________________
13
SFP Copper-Cable Preemphasis Driver MAX3982
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.) 12x16L QFN THIN.EPS
E
1 2
D2 b
0.10 M C A B
D D/2
D2/2
E/2
E2/2
C L
E
(NE - 1) X e
E2
L
C L
e
k (ND - 1) X e
C L
0.10 C 0.08 C A A2 A1 L
C L
L
e
e
PACKAGE OUTLINE 12, 16L, THIN QFN, 3x3x0.8mm
21-0136
14
______________________________________________________________________________________
SFP Copper-Cable Preemphasis Driver
Package Information (continued)
(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.)
MAX3982
EXPOSED PAD VARIATIONS
DOWN BONDS ALLOWED
NOTES: 1. DIMENSIONING & TOLERANCING CONFORM TO ASME Y14.5M-1994. 2. ALL DIMENSIONS ARE IN MILLIMETERS. ANGLES ARE IN DEGREES. 3. N IS THE TOTAL NUMBER OF TERMINALS. 4. THE TERMINAL #1 IDENTIFIER AND TERMINAL NUMBERING CONVENTION SHALL CONFORM TO JESD 95-1 SPP-012. DETAILS OF TERMINAL #1 IDENTIFIER ARE OPTIONAL, BUT MUST BE LOCATED WITHIN THE ZONE INDICATED. THE TERMINAL #1 IDENTIFIER MAY BE EITHER A MOLD OR MARKED FEATURE. 5. DIMENSION b APPLIES TO METALLIZED TERMINAL AND IS MEASURED BETWEEN 0.20 mm AND 0.25 mm FROM TERMINAL TIP. 6. ND AND NE REFER TO THE NUMBER OF TERMINALS ON EACH D AND E SIDE RESPECTIVELY. 7. DEPOPULATION IS POSSIBLE IN A SYMMETRICAL FASHION. 8. COPLANARITY APPLIES TO THE EXPOSED HEAT SINK SLUG AS WELL AS THE TERMINALS. 9. DRAWING CONFORMS TO JEDEC MO220 REVISION C.
PACKAGE OUTLINE 12, 16L, THIN QFN, 3x3x0.8mm
21-0136
E
2
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.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 15 (c) 2004 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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