19-2197; Rev 2; 1/08
KIT
ATION
EVALU
E
BL
AVAILA
2.7Gbps Dual Mux/Buffer with Loopback
General Description
The MAX3783 is a dual serial multiplexer (mux) and
buffer with selectable line-side loopback for system
interconnect and serial backplane applications up to
2.7Gbps. Each independent channel consists of a trans-
mitter with fanout of two and a receiver with a 2:1 input
mux. Selectable loopback paths support system testing.
Operating from a single 3.3V supply, this device has
current-mode logic (CML) inputs and outputs, which
can be AC-coupled for PECL compatibility, if desired.
The IC is packaged in a compact 48-pin TQFP-EP pack-
age with exposed pad. Typical power consumption is
1.12W.
♦
Provides Redundant Serial I/O
♦
11ps Deterministic Jitter
♦
Selectable Loopback
♦
On-Chip 50Ω Termination Resistors
♦
3.3V Power Supply
♦
Two-Port Integration
Features
MAX3783
Applications
2.7Gbps Serial Communications
System Interconnect
Serial Backplane
Fail-Over and Protection Switching
PART
MAX3783UCM
MAX3783UCM+
Ordering Information
TEMP RANGE
0°C to +85°C
0°C to +85°C
PIN-PACKAGE
48 TQFP-EP*
48 TQFP-EP*
*EP = Exposed pad.
+
Denotes a lead-free package.
Pin Configuration
Typical Application Circuit appears at end of data sheet.
V
CC
LO1A+
LO1A-
V
CC
LO2A+
44
43
42
41
40
48
47
46
45
39
38
GND
SIA-
SIA+
V
CC
LB1A
LB2A
LB1B
LB2B
V
CC
SIB+
SIB-
GND
37
36
35
34
33
32
31
30
29
28
27
26
25
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
LO2A-
V
CC
GND
SELA
V
CC
SOA+
SOA-
LI2A+
LI2A-
V
CC
LI1A+
LI1A-
GND
GND
LI1B-
LI1B+
V
CC
LI2B-
LI2B+
MAX3783
*EXPOSED PAD MUST BE SOLDERED TO SUPPLY GROUND ON THE CIRCUIT BOARD.
________________________________________________________________
Maxim Integrated Products
SOB+
SOB-
V
CC
LO1B+
LO1B-
TQFP-EP*
V
CC
LO2B+
LO2B-
V
CC
GND
SELB
V
CC
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
2.7Gbps Dual Mux/Buffer with Loopback
MAX3783
ABSOLUTE MAXIMUM RATINGS
Supply Voltage, V
CC
...............................................-0.5V to 4.0V
Continuous Current at Serial Outputs...............................±36mA
Voltage at SEL_,
LB_
Pins ..........................-0.5V to (V
CC
+ 0.5V)
Common-Mode Input Voltage (SI_, LI_) .....-0.5V to (V
CC
+ 0.5V)
Differential Input Voltage (SI_, LI_) (Note 1) .......................±2.8V
Continuous Power Dissipation (T
A
= +85°C)
48-Pin TQFP-EP (derate 27mW/°C above +85°C) .........1.76W
Storage Ambient Temperature ..........................-55°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Note 1:
The sum of the common-mode voltage and differential voltage on any input pin must be within -0.5V to (V
CC
+ 0.5V).
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
(V
CC
= 3.0V to 3.6V, serial data rate = 2.75Gbps, T
A
= 0°C to +85°C. Typical values at V
CC
= 3.3V, T
A
= +25°C, unless otherwise
noted.)
PARAMETER
Maximum Serial Data Rate
Power Dissipation
Supply Current
CML Differential Output Voltage
CML Differential Input Voltage
CML Output Impedance
CML Input Impedance
Random Jitter
Deterministic Jitter
CML Output Edge Speed
(20% to 80%)
Propagation Delay
Multiplexer Switch Time
TTL Input Current High
TTL Input Current Low
t
R
, t
F
I
CC
V
OD
V
ID
R
OUT
R
IN
Single ended
Differential
(Note 3)
(Notes 3, 4, 5)
2.5Gbps input (Note 6)
1.25Gbps input (Note 3)
LI_ to SO_, SI_ to LO_, LI_ to LO_ (Note 3)
SEL_ or
LB_
to valid output
V
IH
= +2.0V to (V
CC
+0.3V)
V
IL
= -0.3V to +0.8V
R
L
= 50
to V
CC
, or 100 differential (Note 2)
1200
200
42.5
85
AC-coupled inputs, outputs
SYMBOL
CONDITIONS
MIN
2.75
TYP
3.125
1.12
340
1500
1600
50
100
1
11
70
80
340
9
180
440
1.68
466
2200
2200
57.5
116
2
25
135
200
500
ps
RMS
ps
p-p
ps
ps
ns
μA
μA
MAX
UNITS
Gbps
W
mA
mVp-p
mVp-p
Tested using a repeating 1010 pattern at 500Mbps.
AC specifications are guaranteed by design and characterization.
Deterministic jitter is measured with a repeating K28.5 pattern.
With the peak-to-peak input swing on the selected (transmitted) CML input equal to or greater than that on the nonselected
inputs.
Note 6:
AC specifications are guaranteed by test.
Note 2:
Note 3:
Note 4:
Note 5:
2
_______________________________________________________________________________________
2.7Gbps Dual Mux/Buffer with Loopback
Typical Operating Characteristics
(V
CC
= 3.3V, T
A
= +25°C, unless otherwise noted.)
MAX3783
ELECTRICAL EYE DIAGRAM
2.75 Gbps, 2
23
- 1 PRBS PATTERN
MAX3783 toc01
ELECTRICAL EYE DIAGRAM
2.75 Gbps, K28.5 PATTERN
MAX3783 toc02
ELECTRICAL EYE DIAGRAM
3.125 Gbps, K28.5 PATTERN
MAX3783 toc03
195mV/
div
195mV/
div
195mV/
div
88ps/div
88ps/div
88ps/div
SUPPLY CURRENT vs. TEMPERATURE
MAX3783 toc04
CML DIFFERENTIAL OUTPUT VOLTAGE
vs. CML DIFFERENTIAL INPUT VOLTAGE
MEASURED USING 1010
PATTERN, 500Mbps
1.55
V
OD
(V)
MAX3783 toc05
500
1.60
450
SUPPLY CURRENT (mA)
400
1.50
350
1.45
300
250
0
15
30
45
60
75
90
TEMPERATURE (°C)
1.40
200
700
1200
V
ID
(mV)
1700
2200
DETERMINISTIC JITTER vs. CML
DIFFERENTIAL INPUT VOLTAGE
MAX3783 toc06
MULITPLEXER SWITCH TIME
MAX3783 toc07
25
20
LO2A+
DJ (ps)
15
3.125Gbps
10
2.75Gbps
5
LB2A
LO2A-
10ns
9ns
0
200
700
1200
V
ID
(mV)
1700
2200
10ns/div
_______________________________________________________________________________________
3
2.7Gbps Dual Mux/Buffer with Loopback
MAX3783
Pin Description
PIN
1, 12, 24,
30, 31, 37
2
3
4, 9, 14, 17,
20, 23, 27,
34, 38, 41,
44, 47
5
6
7
8
10
11
13
15
16
18
19
21
22
25
26
28
29
32
33
35
36
39
40
42
43
45
46
48
EP
NAME
GND
SIA-
SIA+
Supply Ground
Serial Input A Negative, CML
Serial Input A Positive, CML
FUNCTION
V
CC
LB1A
LB2A
LB1B
LB2B
SIB+
SIB-
SELB
SOB+
SOB-
LO1B+
LO1B-
LO2B+
LO2B-
LI2B+
LI2B-
LI1B+
LI1B-
LI1A-
LI1A+
LI2A-
LI2A+
LO2A-
LO2A+
LO1A-
LO1A+
SOA-
SOA+
SELA
Exposed
Pad
+3.3V Supply
Line Out 1A Loopback Mode Select. TTL low selects loopback.
Line Out 2A Loopback Mode Select. TTL low selects loopback.
Line Out 1B Loopback Mode Select. TTL low selects loopback.
Line Out 2B Loopback Mode Select. TTL low selects loopback.
Serial Input B Positive, CML
Serial Input B Negative, CML
Serial Output B Input Select, TTL
Serial Output B Positive, CML
Serial Output B Negative, CML
Line Out 1B Positive, CML
Line Out 1B Negative, CML
Line Out 2B Positive, CML
Line Out 2B Negative, CML
Line In 2B Positive, CML
Line In 2B Negative, CML
Line In 1B Positive, CML
Line In 1B Negative, CML
Line In 1A Negative, CML
Line In 1A Positive, CML
Line In 2A Negative, CML
Line In 2A Positive, CML
Line Out 2A Negative, CML
Line Out 2A Positive, CML
Line Out 1A Negative, CML
Line Out 1A Positive, CML
Serial Output A Negative, CML
Serial Output A Positive, CML
Serial Out A Input Select, TTL
Ground. Must be soldered to the circuit board for proper thermal and electrical performance (see
the
Exposed-Pad (EP) Package
section).
4
_______________________________________________________________________________________
2.7Gbps Dual Mux/Buffer with Loopback
Functional Diagram
MAX3783
1
SOA
2
CML
V
CC
15kΩ
SELA
0
15kΩ
LB2A
SIA
2
CML
1
CML
0
15kΩ
LB1A
V
CC
2
LO1A
0
1
CML
V
CC
2
LO2A
CML
2
LI2A
CML
2
LI1A
Input Stages
The input amplifiers accept CML or AC-coupled PECL
signals and each input has an on-chip 100Ω differential
impedance for optimal termination, as shown in Figure 1.
MAX3783
V
CC
MAX3783
IN+
50Ω
1.2kΩ
V
CC
- 0.5V
V
CC
50Ω
IN-
Figure 1. Input Structure
1
SOB
2
CML
V
CC
15kΩ
SELB
0
15kΩ
LB2B
SIB
2
CML
1
CML
0
15kΩ
LB1B
V
CC
2
LO1B
0
1
CML
V
CC
2
LO2B
CML
2
LI2B
CML
2
LI1B
Control Lines
TTL-compatible control lines are provided to select the
MAX3783’s operating mode (Table 1). SELA and SELB
set the mux for channels A and B, respectively, to
select LI1_ or LI2_ to connect to the SO_ output.
LB1A,
LB1B, LB2A,
and
LB2B
enable loopback mode for
each of the four LO_ outputs. All control lines are inter-
nally pulled high through 15kΩ resistors.
Table 1. Operating Modes
SEL_
0
1
SO_
LI2_
LI1_
LB_
0
1
LO_
LI_
SI_
Output Buffers
The outputs are high-speed CML interfaces with 50Ω
back termination, as shown in Figure 2.
Detailed Description
The MAX3783 is a 2.7Gbps dual serial mux/buffer with
selectable line-side loopback for system test. Each half
of the MAX3783 provides a transmitter with a fanout of
two and a receiver with a 2:1 mux, as shown in the func-
tional diagram.
Exposed-Pad (EP) Package
The exposed pad on the 48-pin TQFP-EP provides a
very low thermal-resistance path for heat removal from
the IC. The pad is also electrical ground on the
MAX3783 and must be soldered to the circuit board for
proper thermal and electrical performance.
5
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