MAXIM MAX3841ETG

19-2905; Rev 0; 8/03
12.5Gbps CML 2 × 2 Crosspoint Switch
Features
♦ Up to 12.5Gbps Operation
♦ Less Than 10psP-P Deterministic Jitter
♦ Less Than 0.7psRMS Random Jitter
♦ 1.8V, 2.5V, and 3.3V DC-Coupled CML I/O
♦ Independent Output Power-Down
♦ 4mm × 4mm Thin QFN Package
♦ -40°C to +85°C Operation
♦ +3.3V Core Supply
♦ 215mW Power Consumption (Excluding
Termination Currents)
Applications
Ordering Information
OC-192, 10GbE Switch/Line Cards
OC-192, 10GbE Optical Modules
PART
TEMP RANGE
PINPACKAGE
PKG.
CODE
MAX3841ETG
-40°C to +85°C
24 Thin QFN
T2444-1
System Redundancy/Self Test
Clock Fanout
Pin Configuration appears at end of data sheet.
Typical Application Circuit
1.8V
3.3V
10Gbps
SERIAL
OPTICAL
MODULE
2.5V
3.3V
1.8V
VCC1OUT
VCC
VCC2IN
10Gbps
CDR/SERDES
ASIC
2.5V
SDI+
OUT1+
SDI-
OUT1IN1+
SDO+
MAX3841
SDO+
IN2-
SDO-
OUT2+
SDI+
SDI-
OUT2-
IN1-
SDO-
IN2+
2.5V
1.8V
VCC1IN
SEL1 SEL2
VCC2OUT
ENO1
ENO2
GND
LOOPBACK
________________________________________________________________ Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
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1
MAX3841
General Description
The MAX3841 is a low-power, 12.5Gbps 2 × 2 crosspoint switch IC for high-speed serial data loopback,
redundancy, and switching applications. The MAX3841
current-mode logic (CML) inputs and outputs have isolated VCC connections to enable DC-coupled interfaces
to 1.8V, 2.5V, or 3.3V CML ICs. Fully differential signal
paths and Maxim’s second-generation SiGe technology
provide optimum signal integrity, minimizing jitter,
crosstalk, and signal skew. The MAX3841 is ideal for
serial OC-192 and 10GbE optical module, line card,
switch fabric, and similar applications.
The MAX3841 has 150mVP-P minimum differential input
sensitivity, and 500mVP-P nominal differential output
swing. Unused outputs can be powered down individually to conserve power. In addition to functioning as a 2
× 2 switch, the MAX3841 can be configured as a 2:1
multiplexer, 1:2 buffer, or dual 1:1 buffer. The MAX3841
is available in a 4mm × 4mm 24-pin thin QFN package,
and consumes only 215mW with both outputs enabled.
MAX3841
12.5Gbps CML 2 × 2 Crosspoint Switch
ABSOLUTE MAXIMUM RATINGS
Supply Voltage, VCC..............................................-0.5V to +4.0V
CML Supply Voltage (VCC_IN, VCC_OUT)...........-0.5V to +4.0V
Continuous Output Current (OUT1±, OUT2±)...................±25mA
CML Input Voltage (IN1±, IN2±)...........-0.5V to (VCC_IN + 0.5V)
LVCMOS Input Voltage (SEL1, SEL2,
ENO1, ENO2) .........................................-0.5V to (VCC + 0.5V)
Continuous Power Dissipation (TA = +85°C)
24-Pin Thin QFN (derate 20.8mW/°C
above +85°C).............................................................1352mW
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range .............................-55°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°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, VCC_IN = +1.71V to VCC, VCC_OUT = +1.71V to VCC, TA = -40°C to +85°C. Typical values are at VCC =
+3.3V, VCC_IN = VCC_OUT = 1.8V, TA = +25°C, unless otherwise noted.)
PARAMETER
Core Supply Current
SYMBOL
Excluding CML termination currents
VIN
AC-coupled or DC-coupled (Note 2)
Data Rate
CML Input Differential
CONDITIONS
ICC
(Note 1)
CML Input Common Mode
DC-coupled
CML Input Termination
Single ended
CML Input Return Loss
CML Output Differential
MAX
UNITS
65
90
mA
0
12.5
Gbps
1200
mVP-P
VCC_IN - 0.3
VCC_IN
V
57.5
Ω
500
600
mVP-P
50
57.5
Ω
42.5
50
(Note 2)
400
Single ended
42.5
12
dB
20% to 80% (Notes 1, 3)
30
ps
Deterministic Jitter
(Notes 1, 4)
10
psP-P
Random Jitter
VIN = 150mVP-P (Notes 1, 5)
0.3
0.7
psRMS
Propagation Delay
Any input to output (Note 1)
100
140
ps
Channel-to-Channel Skew
(Note 1)
12
ps
Output Duty-Cycle Skew
50% input duty cycle (Notes 1, 3)
8
ps
+10
µA
LVCMOS Input Current
LVCMOS Input High Voltage
tR, tF
TYP
150
Up to 10GHz
VOUT
CML Output Termination
CML Output Transition Time
MIN
IIH, IIL
-10
VIH
1.7
V
Guaranteed by design and characterization.
Differential swing is defined as VIN = (IN_+) - (IN_-) and VOUT = (OUT_+) - (OUT_-). See Figure 1.
Measured using a 0000011111 pattern at 12.5Gbps, and VIN = 400mVP-P differential.
Measured at 9.953Gbps using a pattern of 100 ones, 27 - 1 PRBS, 100 zeros, 27 - 1 PRBS, and at 12.5Gbps using a ±K28.5
pattern. VCC_IN = VCC_OUT = 1.8V, and VIN = 400mVP-P differential.
Note 5: Refer to Maxim application note HFAN-04.5.1: Measuring Random Jitter on a Digital Sampling Oscilloscope.
Note 1:
Note 2:
Note 3:
Note 4:
2
_______________________________________________________________________________________
12.5Gbps CML 2 × 2 Crosspoint Switch
110
0 OUTPUTS ENABLE
100
1 OUTPUT ENABLE
90
2 OUTPUTS ENABLE
80
130
70
110
80
70
60
50
40
40
10
35
60
60mV/div
0 OUTPUTS ENABLE
90
50
-15
1 OUTPUT ENABLE
100
60
-40
2 OUTPUTS ENABLE
120
SUPPLY CURRENT (mA)
SUPPLY CURRENT (mA)
120
CML INPUTS AND OUTPUTS AC-COUPLED
-40
85
-15
10
35
60
TEMPERATURE (°C)
TEMPERATURE (°C)
OUTPUT EYE DIAGRAM
(10.7Gbps, 223 - 1 PRBS)
OUTPUT EYE DIAGRAM
(6.25Gbps, 223 - 1 PRBS)
MAX3841 toc04
OUTPUT EYE DIAGRAM
(622Mbps, 223 - 1 PRBS)
MAX3841 toc06
60mV/div
60mV/div
28ps/div
270ps/div
DETERMINISTIC JITTER
vs. TEMPERATURE
DIFFERENTIAL OUTPUT SWING
vs. TEMPERATURE
PROPAGATION DELAY
12
10
8
6
4
MAX3841 toc09
MAX3841 toc08
550
540
DIFFERENTIAL OUTPUT (mVP-P)
27 - 1 PRBS + 100CIDs
AT 10.7Gbps
14
MAX3841 toc07
16ps/div
16
2
14ps/div
85
MAX3841 toc05
60mV/div
DETERMINISTIC JITTER (ps)
MAX3841 toc02
130
MAX3841 toc03
140
MAX3841 toc01
140
OUTPUT EYE DIAGRAM
(12.5Gbps, 223 - 1 PRBS)
SUPPLY CURRENT vs. TEMPERATURE
(CORE PLUS CML I/O CURRENTS)
CORE SUPPLY CURRENT vs. TEMPERATURE
(EXCLUDES CML I/O CURRENTS)
530
IN1
520
510
500
490
480
OUT1
470
460
±K28.5 AT 12.5Gbps
450
0
-40
-15
10
35
TEMPERATURE (°C)
60
85
-40
-15
10
35
60
85
100ps/div
TEMPERATURE (°C)
_______________________________________________________________________________________
3
MAX3841
Typical Operating Characteristics
(VCC = 3.3V, VCC_IN, VCC_OUT = 1.8V, VIN = 500mVP-P, TA = +25°C, unless otherwise noted.)
12.5Gbps CML 2 × 2 Crosspoint Switch
MAX3841
Pin Description
PIN
NAME
1, 12
VCC
FUNCTION
2, 5
VCC1IN
3
IN1+
Positive Serial Data Input 1, CML
4
IN1-
Negative Serial Data Input 1, CML
6
SEL1
Output 1 Select, LVCMOS Input. See Table 1.
7
SEL2
Output 2 Select, LVCMOS Input. See Table 1.
8, 11
VCC2IN
+3.3V Core Supply Voltage
Supply Voltage for CML Input IN1. Connect to 1.8V, 2.5V, or 3.3V.
Supply Voltage for CML Input IN2. Connect to 1.8V, 2.5V, or 3.3V.
9
IN2+
Positive Serial Data Input 2, CML
10
IN2-
Negative Serial Data Input 2, CML
13, 24
GND
Supply Ground
14, 17
VCC1OUT
15
OUT1-
Negative Serial Data Output 1, CML
16
OUT1+
Positive Serial Data Output 1, CML
18
ENO1
Output 1 Enable, LVCMOS Input. See Table 1.
Output 2 Enable, LVCMOS Input. See Table 1.
19
ENO2
20, 23
VCC2OUT
21
OUT2-
22
OUT2+
EP
Exposed Pad
Supply Voltage for CML Output OUT1. Connect to 1.8V, 2.5V, or 3.3V.
Supply Voltage for CML Output OUT2. Connect to 1.8V, 2.5V, or 3.3V.
Negative Serial Data Output 2, CML
Positive Serial Data Output 2, CML
Ground. The exposed pad must be soldered to the circuit board ground for proper thermal and
electrical performance.
Detailed Description
The MAX3841 contains a pair of CML inputs that drive
two 2:1 multiplexers, with separate select inputs SEL1
and SEL2, providing a 2 × 2 crosspoint data path. The
outputs of the multiplexers each drive a high-performance CML output that can be disabled (powered
down) using the ENO1/ENO2 inputs. All of the data
paths are fully differential to minimize jitter, crosstalk,
and signal skew. See Figure 1 for the functional diagram.
The CML inputs accept serial NRZ data with differential
amplitude from 150mVP-P to 1200mVP-P (see Figure 2).
The CML outputs provide 500mVP-P nominal differential
swing, resulting in low power consumption.
2
IN1
CML
1
2
OUT1
CML
0
ENO1
CML Input and Output Buffers
The MAX3841 input and output buffers are terminated
with 50Ω to independent supply lines, and are also compatible with 100Ω differential terminations. (See Figures 3
and 4.) Separate power-supply connections are provided
for the core, input buffers, and output buffers to allow DCcoupling to 1.8V, 2.5V, or 3.3V CML ICs. If desired, the
CML inputs and outputs can be AC-coupled.
SEL1
2
IN2
CML
1
2
CML
ENO2
MAX3841
Figure 1. Functional Diagram
4
OUT2
0
_______________________________________________________________________________________
SEL2
12.5Gbps CML 2 × 2 Crosspoint Switch
75mV
MIN
600mV
MAX
V+
150mV
MIN
(V+) - (V-)
1200mV
MAX
ENO1
ENO2
SEL1
SEL2
OUT1
OUT2
0
0
0
0
IN2
IN1
0
0
0
1
IN2
IN2
0
0
1
0
IN1
IN1
0
0
1
1
IN1
IN2
1
1
X
X
Disabled
Disabled
Applications Information
Select and Enable Controls
The MAX3841 provides two LVCMOS-compatible
select inputs, SEL1 and SEL2. Either data input can be
connected to either or both data outputs. The MAX3841
provides two LVCMOS-compatible enable inputs,
ENO1 and ENO2, so each output can be disabled
independently. The MAX3841 can also be used as a
1:2 driver, 2:1 multiplexer, or a dual 1:1 buffer by using
the LVCMOS control inputs accordingly (see Table 1).
Figure 2. Definition of Differential Voltage Swing
VCC_IN
50Ω
50Ω
Power-Supply Connections
IN_+
Each of the input and output power-supply connections
(VCC1IN, VCC2IN, VCC1OUT, VCC2OUT) is independent and need not be connected to the same voltage.
The input and output supplies can be connected to
1.8V, 2.5V, or 3.3V, but the core supply (VCC) must be
connected to 3.3V for proper operation.
IN_-
MAX3841
Input and Output Interfaces
Figure 3. Equivalent CML Input Circuit
The MAX3841 inputs and outputs can be AC-coupled
or DC-coupled according to the application. If an input
or output is not used it should be terminated with 50Ω
to the correct input or output supply voltage. For more
information about interfacing with logic families, refer to
Maxim application note HFAN-01.0: Introduction to
LVDS, PECL, and CML.
VCC_OUT
50Ω
50Ω
OUT_+
OUT_-
MAX3841
Package and Layout Considerations
The MAX3841 is packaged in a 4mm × 4mm 24-pin thin
QFN with exposed pad. The exposed pad provides
thermal and electrical connectivity to the IC and must
be soldered to a high-frequency ground plane. Use
multiple vias to connect the exposed pad underneath
the package to the PC board ground plane.
Use good layout techniques for the 10Gbps PC board
transmission lines, and configure the layout near the IC to
minimize impedance discontinuities. Power-supply
decoupling capacitors should be located as close as
possible to the IC.
Figure 4. Equivalent CML Output Circuit
_______________________________________________________________________________________
5
MAX3841
Table 1. Output Controls
V-
12.5Gbps CML 2 × 2 Crosspoint Switch
Chip Information
TRANSISTOR COUNT: 950
PROCESS: SiGe BiCMOS
ENO2
VCC2OUT
OUT2-
OUT2+
GND
TOP VIEW
VCC2OUT
MAX3841
Pin Configuration
24 23 22 21 20 19
VCC
1
18 ENO1
VCC1IN
2
17 VCC1OUT
IN1+
3
IN1-
4
VCC1IN
5
14 VCC1OUT
SEL1
6
13 GND
16 OUT1+
MAX3841
9
10 11 12
SEL2
IN2+
IN2-
VCC
8
VCC2IN
7
VCC2IN
15 OUT1-
THIN QFN*
*THE EXPOSED PAD OF THE QFN PACKAGE MUST BE
SOLDERED TO GROUND FOR PROPER THERMAL AND
ELECTRICAL OPERATION.
6
_______________________________________________________________________________________
12.5Gbps CML 2 × 2 Crosspoint Switch
24L QFN THIN.EPS
PACKAGE OUTLINE
12,16,20,24L QFN THIN, 4x4x0.8 mm
21-0139
A
_______________________________________________________________________________________
7
MAX3841
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.)
MAX3841
12.5Gbps CML 2 × 2 Crosspoint Switch
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.)
PACKAGE OUTLINE
12,16,20,24L QFN THIN, 4x4x0.8 mm
21-0139
A
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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