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19-4800; Rev 0; 3/00
3.3V, 622Mbps LVDS, Dual 4:2 Crosspoint Switch
General Description
The MAX3640 is a dual-path crosspoint switch for use at OC-12 data rates. The MAX3640 can be used to receive and transmit 622Mbps low-voltage differential signals (LVDS) across a backplane with minimum jitter accumulation. Each path incorporates input buffers, multiplexers, a crosspoint switch, and output drivers. The four output channels have a redundant set of outputs for test or fanning purposes. The device offers signal-path redundancy for critical data streams. The MAX3640 has a unique power-saving feature. When a set of four output channels has been de-selected, the output drivers are powered down to reduce power consumption by 165mW. The fully differential architecture ensures low crosstalk, jitter accumulation, and signal skew. The MAX3640 is available in a 48-pin TQFP package and operates from a +3.3V supply over the 0C to +85C temperature range. o Single +3.3V Supply o 257mW Power Consumption (four output channels enabled) o 2.8psRMS Output Random Jitter o 42ps Output Deterministic Jitter o Power-Down Feature for Deselected Outputs o 110ps Channel-to-Channel Skew o 240ps Output Edge Speed o LVDS Inputs/Outputs o LVDS Output 3-State Enable
Features
MAX3640
Applications
SONET/SDH Backplanes High-Speed Parallel Links Digital Cross-Connects System Interconnects ATM Switch Cores
PART MAX3640UCM
Ordering Information
TEMP. RANGE 0C to +85C PIN-PACKAGE 48 TQFP
Pin Configuration appears at end of data sheet.
Typical Operating Circuit
MAX3869 LASER DRIVER OPTICAL TRANSCEIVER 2.5Gbps MAX3831 4-CHANNEL INTERCONNECT MUX/DEMUX 622Mbps
SONET SOURCE A MAX3640 CROSSPOINT SWITCH SONET SOURCE B 622Mbps
MAX3866 TIA AND LA
MAX3876 CDR
PARALLEL DATA OUTPUT
________________________________________________________________ Maxim Integrated Products
1
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3.3V, 622Mbps LVDS, Dual 4:2 Crosspoint Switch MAX3640
ABSOLUTE MAXIMUM RATINGS
Supply Voltage, VCC ................................................-0.5V to 5.0V Input Voltage (LVDS, TTL)..........................-0.5V to (VCC + 0.5V) Output Voltage (LVDS) ...............................-0.5V to (VCC + 0.5V) Continuous Power Dissipation (TA = +85C) 48-Pin TQFP (derate 12.5mW/C) .................................813mW Operating Temperature Range...............................0C to +85C Storage Temperature Range ............................ -55C to +150C Lead Temperature (soldering, 10s) .................................+300C
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.
DC ELECTRICAL CHARACTERISTICS
(VCC = +3.0V to 3.6V, LVDS differential load = 100 1%, TA = 0C to +85C. Typical values are at VCC = +3.3V, TA = +25C, unless otherwise noted.)
PARAMETER Supply Current LVDS INPUTS AND OUTPUTS Input Voltage Range Differential Input Threshold Threshold Hysteresis Differential Input Impedance Input Common-Mode Current Output Voltage High Output Voltage Low Output Voltage Swing Change in Magnitude of Differential Output for Complementary States Offset Output Voltage Change in Magnitude of Output Offset Voltage for Complementary States Differential Output Impedance Output Current TTL INPUTS Input Voltage High Input Voltage Low Input Current High Input Current Low VIH VIL IIH IIL VIH = 2.0V VIL = 0.8V -250 -550 2.0 0.8 V V A A VIN VIDTH VHYST RIN IOS VOH VOL |VOD| |VOD| VOS |VOS| ENA, ENB = GND ENA, ENB = VCC Shorted together 80 1 120 12 Figure 1 1.125 LVDS input, VOS = 1.2V Figure 1 Figure 1 Figure 1 0.925 250 400 25 1.275 25 85 0 -100 90 100 245 1.475 115 2400 100 mV mV mV A V V mV mV mV mV M mA SYMBOL ICC CONDITIONS Eight outputs enabled Four outputs enabled MIN TYP 130 78 MAX 175 UNITS mA
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3.3V, 622Mbps LVDS, Dual 4:2 Crosspoint Switch
AC ELECTRICAL CHARACTERISTICS
(VCC = +3.0V to 3.6V, LVDS differential load = 100 1%, TA = 0C to +85C. Typical values are at VCC = +3.3V, TA = +25C, unless otherwise noted.) (Note 1)
PARAMETER Parallel Input/Output Data Rate Output Rise/Fall Time Output Random Jitter Output Deterministic Jitter LVDS Output Differential Skew LVDS Output Channel-toChannel Skew LVDS Output Enable Time LVDS Output Disable Time LVDS Propagation Delay from Input to Output tD tr, tf RJ DJ tSKEW1 tSKEW2 266 66 2.5 (Note 2) 20% to 80% 150 SYMBOL CONDITIONS MIN TYP 622 240 2.8 42 24 350 4 200 50 110 MAX UNITS Mbps ps psRMS ps ps ps ns ns ns
MAX3640
Note 1: AC characteristics are guaranteed by design and characterization. Note 2: Deterministic jitter (DJ) is the arithmetic sum of pattern-dependent jitter and pulse-width distortion. DJ is measured while applying 100mVp-p noise (f 2MHz) to the power supply.
VOH LVDS+ SINGLE ENDED 125mV MIN 200mV MAX VOS = 1.2V 75mV 250mV MIN 400mV MAX VOL
VOH 250mV MIN 400mV MAX VOL
VOS = 1.2V 75mV LVDSSINGLE ENDED 125mV MIN 200mV MAX
VOD 250mV MIN 400mV MAX 0 (LVDS+) - (LVDS-) DIFFERENTIAL OUTPUT VOLTAGE 500mV MIN 800mV MAX
Figure 1. LVDS Output Levels _______________________________________________________________________________________ 3
3.3V, 622Mbps LVDS, Dual 4:2 Crosspoint Switch MAX3640
Typical Operating Characteristics
(VCC = +3.3V, TA = +25C, unless otherwise noted.)
DIFFERENTIAL OUTPUT VOLTAGE vs. TEMPERATURE
MAX3640 toc01
SUPPLY CURRENT vs. TEMPERATURE
150 140 130 SUPPLY CURRENT (mA) 120 110 100 90 80 70 60 50 0 10 20 30 40 50 60 70 80 TEMPERATURE (C) 4 OUTPUTS ENABLED 8 OUTPUTS ENABLED 640 DIFFERENTIAL OUTPUT VOLTAGE (mVp-p) 630 620 610 600 590 580 570 560 0
20
40 TEMPERATURE (C)
60
80
622Mbps EYE DIAGRAM
MAX3640 toc03
1.25Gbps EYE DIAGRAM
INPUT = 213 - 1 PRBS CONTAINS 100 ZEROS
MAX3640 toc04
INPUT = 213 - 1 PRBS CONTAINS 100 ZEROS
100mV/div
100mV/div
200ps/div
100ps/div
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MAX3640 toc02
3.3V, 622Mbps LVDS, Dual 4:2 Crosspoint Switch MAX3640
Pin Description
PIN 1, 12, 25, 36, 41 2, 11, 26, 35 3, 5, 45, 47 4, 6, 46, 48 7, 9, 13, 15 8, 10, 14, 16 17-20 21, 23, 27, 29 22, 24, 28, 30 31, 33, 37, 39 32, 34, 38, 40 42 43 44 NAME VCC GND DIA3+, DIA4+, DIA1+, DIA2+ DIA3-, DIA4-, DIA1-, DIA2DIB1+, DIB2+, DIB3+, DIB4+ DIB1-, DIB2-, DIB3-, DIB4SEL1-SEL4 DOB4-, DOB3-, DOB2-, DOB1DOB4+, DOB3+, DOB2+, DOB1+ DOA4-, DOA3-, DOA2-, DOA1DOA4+, DOA3+, DOA2+, DOA1+ ENB ENA IN_SEL Positive Supply Voltage Supply Ground Positive LVDS, Channel-A Data Input Negative LVDS, Channel-A Data Input Positive LVDS, Channel-B Data Input Negative LVDS, Channel-B Data Input Crosspoint Switch Select, TTL Input. (Table 1) Negative LVDS, Channel-B Data Output Positive LVDS, Channel-B Data Output Negative LVDS, Channel-A Data Output Positive LVDS, Channel-A Data Output Channel-B Output Enable, TTL Input. ENB = high enables DOB1-DOB4. ENB = low powers down DOB1-DOB4 and sets them to a high-impedance state. Channel-A Output Enable, TTL Input. ENA = high enables DOA1-DOA4. ENA = low powers down DOA1-DOA4 and sets them to a high-impedance state. Input Select Pin, TTL Input. Connect to logic high (or VCC) to select DIA1-DIA4. Connect to logic low (or GND) to select DIB1-DIB4. FUNCTION
Detailed Description
Figure 2 shows the MAX3640's architecture. It consists of two data paths; each data path begins with four differential input buffers. The IN_SEL pin selects whether the A or B channels are passed to the 2x2 crosspoint switch that follows. The SEL_ pins control the routing of the crosspoint switch. Each crosspoint switch output drives a pair of LVDS output drivers. This provides a redundant set of outputs that can be used for fan-out or test purposes. Each set of outputs, DOA_ and DOB_, is enabled or disabled by the ENA and ENB pins. See Table 1 for routing controls.
LVDS Inputs and Outputs
The MAX3640 features LVDS inputs and outputs for interfacing with high-speed digital circuitry. The LVDS standard is based on the IEEE 1596.3 LVDS specification. This technology uses 500mV to 800mV differential low-voltage swings to achieve fast transition times, low power dissipation, and improved noise immunity. For proper operation, the data outputs require 100 differential termination between the inverting and noninverting pins. Do not terminate these outputs to ground. See Figure 1 for LVDS output voltage specifications. The data inputs are internally terminated with 100 differential and therefore do not require external termination.
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3.3V, 622Mbps LVDS, Dual 4:2 Crosspoint Switch MAX3640
DIA1+ 1 DIA1-
2x2 CROSSPOINT SWITCH 0
MAX3640
DOA1+
DOA1DIB1+ 0 DIB1DOB1SEL1 1
DOB1+
DIA2+ 1 DIA20
DOA2+
DOA2-
DIB2+ 1 0 DIB2-
DOB2+
DOB2-
SEL2 DIA3+ 1 DIA32x2 CROSSPOINT SWITCH 0 DOA3DIB3+ 0 DIB3DOB3SEL3 DIA4+ DOA4+ 1 DIA40 DOA4DIB4+ 0 DIB4DOB4SEL4 1 DOB4+ 1 DOB3+
DOA3+
IN_SEL
ENA
ENB
Figure 2. Functional Diagram
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3.3V, 622Mbps LVDS, Dual 4:2 Crosspoint Switch MAX3640
Table 1. Output Routing
ROUTING CONTROLS IN_SEL SEL1 SEL2 0 0 0 0 1 1 1 1 IN_SEL 0 0 0 0 1 1 1 1 0 0 1 1 0 0 1 1 SEL3 0 0 1 1 0 0 1 1 0 1 0 1 0 1 0 1 SEL4 0 1 0 1 0 1 0 1 OUTPUT SIGNALS Signal at DOA1/DOB1 DIB1 DIB1 DIB2 DIB2 DIA1 DIA1 DIA2 DIA2 Signal at DOA3/DOB3 DIB3 DIB3 DIB4 DIB4 DIA3 DIA3 DIA4 DIA4 Signal at DOA2/DOB2 DIB1 DIB2 DIB1 DIB2 DIA1 DIA2 DIA1 DIA2 Signal at DOA4/DOB4 DIB3 DIB4 DIB3 DIB4 DIA3 DIA4 DIA3 DIA4
Note: Disabling the outputs by using ENA or ENB will drive the DOA_ or DOB_ data outputs to a high-impedance state.
+3.3V
182 48 Zo = 50 LVPECL DRIVER Zo = 50 48 182
48
MAX3640
48
+3.3V
Figure 3. LVPECL to LVDS Interface
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3.3V, 622Mbps LVDS, Dual 4:2 Crosspoint Switch MAX3640
Applications Information
Interfacing LVPECL Outputs to MAX3640 LVDS Inputs
To DC-couple between LVPECL and LVDS, use the resistor network shown in Figure 3. Note that the LVPECL output is optimized for a 50 load to VCC - 2V, so an equivalent network is used. Also, the network attenuation should be such that the LVPECL output signal after attenuation is well within the LVDS input range. Note that the LVDS input impedance is a true 100 between the inputs. The differential impedance does not contribute to the DC termination impedance, but does contribute to the AC termination impedance. This means that AC and DC impedance will always be different.
Layout Techniques
For best performance, use good high-frequency layout techniques. Filter voltage supplies, and keep ground connections short. Use multiple vias where possible. Also, use controlled-impedance transmission lines to interface with the MAX3640 data inputs and outputs.
Interface Models
Figure 4 shows the interface model for the LVDS inputs, while Figure 5 shows the model for the LVDS outputs.
VCC
VCC
MAX3640
25k
DIA1+
1.5k
5k 50
VCC 50
DIA11.5k
Figure 4. LVDS Input Model
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3.3V, 622Mbps LVDS, Dual 4:2 Crosspoint Switch MAX3640
Chip Information
VCC
TRANSISTOR COUNT: 2453
VCC
45 45 VCC
DOA1+
DOA1-
MAX3640
Figure 5. LVDS Output Model
Pin Configuration
IN_SEL DOA1+ DOA2+
38
DOA139
48
47
46
45
44
43
42
41
40
37
DOA2-
DIA2+
DIA1+
DIA2-
DIA1-
ENA
ENB VCC
VCC GND DIA3+ DIA3DIA4+ DIA4DIB1+ DIB1DIB2+ DIB2GND VCC
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
36 35 34 33 32 31 30 29 28 27 26 25
VCC GND DOA3+ DOA3DOA4+ DOA4DOB1+ DOB1DOB2+ DOB2GND VCC
MAX3640
DIB3+ DIB3DIB4+ DIB4SEL1 SEL2 SEL3 SEL4 DOB4DOB4+ DOB3DOB3+
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3.3V, 622Mbps LVDS, Dual 4:2 Crosspoint Switch MAX3640
Package Information
32L/48L,TQFP.EPS
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3.3V, 622Mbps LVDS, Dual 4:2 Crosspoint Switch MAX3640
NOTES
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3.3V, 622Mbps LVDS, Dual 4:2 Crosspoint Switch MAX3640
NOTES
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.
12 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2000 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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