19-3162; Rev 3; 6/11
KIT
ATION
EVALU
BLE
AVAILA
155Mbps to 4.25Gbps SFF/SFP Laser Driver
with Extinction Ratio Control
General Description
The MAX3738 is a +3.3V laser driver designed for mul-
tirate transceiver modules with data rates from
155Mbps to 4.25Gbps. Lasers can be DC-coupled to
the MAX3738 for reduced component count and ease
of multirate operation.
Laser extinction ratio control (ERC) combines the features
of automatic power control (APC), modulation compensa-
tion, and built-in thermal compensation. The APC loop
maintains constant average optical power. Modulation
compensation increases the modulation current in pro-
portion to the bias current. These control loops, com-
bined with thermal compensation, maintain a constant
optical extinction ratio over temperature and lifetime.
The MAX3738 accepts differential data input signals.
The wide 5mA to 60mA (up to 85mA AC-coupled) mod-
ulation current range and up to 100mA bias current
range, make the MAX3738 ideal for driving FP/DFB
lasers in fiber optic modules. External resistors set the
required laser current levels. The MAX3738 provides
transmit disable control (TX_DISABLE), single-point
fault tolerance, bias-current monitoring, and photocur-
rent monitoring. The device also offers a latched failure
output (TX_FAULT) to indicate faults, such as when the
APC loop is no longer able to maintain the average
optical power at the required level. The MAX3738 is
compliant with the SFF-8472 transmitter diagnostic and
SFP MSA timing requirements.
The MAX3738 is offered in a 4mm x 4mm, 24-pin thin
QFN package and operates over the extended -40°C to
+85°C temperature range.
♦
Single +3.3V Power Supply
♦
47mA Power-Supply Current
♦
85mA Modulation Current
♦
100mA Bias Current
♦
Automatic Power Control (APC)
♦
Modulation Compensation
♦
On-Chip Temperature Compensation
♦
Self-Biased Inputs for AC-Coupling
♦
Ground-Referenced Current Monitors
♦
Laser Shutdown and Alarm Outputs
♦
Enable Control and Laser Safety Feature
Features
MAX3738
Ordering Information
PART
MAX3738ETG
MAX3738ETG+
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
24 Thin QFN-EP*
24 Thin QFN-EP*
+Denotes
a lead(Pb)-free/RoHS-compliant package.
*EP
= Exposed pad.
Pin Configuration
MODBCOMP
TH_TEMP
APCFILT2
20
MODSET
APCSET
TOP VIEW
APCFILT1
19
18 MD
17 V
CC
16 OUT+
15 OUT-
14 V
CC
*EP
7
PC_MON
8
BC_MON
9
SHUTDOWN
10
GND
11
TX_FAULT
12
GND
13 BIAS
Applications
Multirate OC-3 to OC-48 FEC Transceivers
Gigabit Ethernet SFF/SFP and GBIC
Transceivers
1Gbps/2Gbps/4Gbps Fibre Channel SFF/SFP
and GBIC Transceivers
MODTCOMP 1
V
CC
2
IN+ 3
IN- 4
V
CC
5
TX_DISABLE 6
24
23
22
21
MAX3738
Typical Application Circuit appears at end of data sheet.
*THE EXPOSED PADDLE MUST BE SOLDERED TO SUPPLY
GROUND ON THE CIRCUIT BOARD.
PIN1 INDICATED BY + ON LEAD-FREE PACKAGE.
________________________________________________________________
Maxim Integrated Products
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.
155Mbps to 4.25Gbps SFF/SFP Laser Driver
with Extinction Ratio Control
MAX3738
ABSOLUTE MAXIMUM RATINGS
Supply Voltage V
CC
...............................................-0.5V to +6.0V
IN+, IN-, TX_DISABLE, TX_FAULT, SHUTDOWN,
BC_MON, PC_MON, APCFILT1, APCFILT2,
MD, TH_TEMP, MODTCOMP, MODBCOMP,
MODSET, and APCSET Voltage.............-0.5V to (V
CC
+ 0.5V)
OUT+, OUT-, BIAS Current.............................-20mA to +150mA
Continuous Power Dissipation (T
A
= +70°C)
TQFN (derate 27.8mW/°C above +70°C) ..................2222mW
Operating Junction Temperature Range ...........-55°C to +150°C
Storage Temperature Range .............................-55°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Soldering Temperature (reflow)
Lead(Pb)-free...............................................................+260°C
Containing lead(Pb) .....................................................+240°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
(V
CC
= +2.97V to +3.63V, T
A
= -40°C to +85°C. Typical values are at V
CC
= +3.3V, I
BIAS
= 60mA, I
MOD
= 60mA, T
A
= +25°C, unless
otherwise noted.) (Notes 1, 2)
PARAMETER
POWER SUPPLY
Supply Current
Power-Supply Noise Rejection
I/O SPECIFICATIONS
Differential Input Swing
Common-Mode Input
LASER BIAS
Bias-Current-Setting Range
Bias Off Current
Bias-Current Monitor Ratio
LASER MODULATION
Modulation Current-Setting
Range
Output Edge Speed
Output Overshoot/Undershoot
Random Jitter
(Notes 6, 7)
2.7Gbps, 5mA
Deterministic Jitter (Notes 6, 8)
1.25Gbps, 5mA
622Mbps, 5mA
155Mbps, 5mA
Modulation-Current Temperature
Stability
Modulation-Current-Setting Error
Modulation Off Current
(Note 6)
15 load,
T
A
= +25°C
I
MOD
I
MOD
I
MOD
I
MOD
5mA
10mA
5mA
85mA
85mA
85mA
85mA
I
MOD
I
MOD
I
MOD
10mA
85mA
10mA
85mA
I
MOD
(Note 5)
20% to 80%
(Notes 6, 7)
5mA
I
MOD
85mA
5
65
±6
0.62
18
20
24
45
±175
±125
1.3
40
41
46
100
±600
±480
±20
±15
0.1
ppm/°C
%
mA
ps
P-P
85
80
mA
ps
%
ps
RMS
TX_DISABLE = high
I
BIAS
/ I
BC_MON
62
76
1
100
0.1
90
mA
mA
mA/mA
V
ID
V
CM
DC-coupled, Figure 1
0.2
1.7
2.4
V
CC
-
V
ID
/ 4
V
P-P
V
I
CC
PSNR
(Note 3)
f
1MHz, 100mA
P-P
(Note 4)
47
33
60
mA
dB
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
10mA < I
MOD
TX_DISABLE = high
2
_______________________________________________________________________________________
155Mbps to 4.25Gbps SFF/SFP Laser Driver
with Extinction Ratio Control
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= +2.97V to +3.63V, T
A
= -40°C to +85°C. Typical values are at V
CC
= +3.3V, I
BIAS
= 60mA, I
MOD
= 60mA, T
A
= +25°C, unless
otherwise noted.) (Notes 1, 2)
PARAMETER
Monitor-Diode Input Current
Range
MD Pin Voltage
MD Current Monitor Ratio
APC Loop Time Constant
APC Setting Stability
APC Setting Accuracy
I
MOD
Compensation-Setting
Range by Bias
I
MOD
Compensation-Setting
Range by Temperature
Threshold-Setting Range for
Temperature Compensation
LASER SAFETY AND CONTROL
Bias and Modulation Turn-Off
Delay
Bias and Modulation Turn-On
Delay
Threshold Voltage at Monitor
INTERFACE SIGNALS
TX_DISABLE Input High
TX_DISABLE Input Low
TX_DISABLE Input Current
TX_FAULT Output Low
Shutdown Output High
Shutdown Output Low
V
HI
V
LO
R
PULL
= 45k
V
HI
= V
CC
V
LO
= V
GND
Sinking 1mA, open collector
Sourcing 100μA
Sinking 100μA
V
CC
- 0.4
0.4
-70
(typ)
2.0
0.8
15
-140
0.4
V
V
μA
V
V
V
V
REF
C
APC_FILT
= 0.01μF, I
MD
/ I
BIAS
= 1/80
(Note 6)
C
APC_FILT
= 0.01μF, I
MD
/ I
BIAS
= 1/80
(Note 6)
Figure 5
1.14
1.3
5
600
1.39
μs
μs
V
K
TC
T
TH
I
MD
/ I
PC_MON
C
APC_FILT
= 0.01μF, I
MD
/ I
BIAS
= 1/70
(Note 6)
T
A
= +25°C
K = I
MOD
/ I
BIAS
TC = I
MOD
/ T (Note 6)
(Note 6)
0
0
+10
0.85
0.93
3.3
±100
±480
±15
1.5
1.0
+60
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MAX3738
AUTOMATIC POWER AND EXTINCTION RATIO CONTROLS
I
MD
Average current into the MD pin
18
1500
1.4
1.15
μA
V
mA/mA
μs
ppm/°C
%
mA/mA
mA/°C
°C
Note 1:
Note 2:
Note 3:
Note 4:
Note 5:
Note 6:
Note 7:
Note 8:
AC characterization is performed using the circuit in Figure 2 using a PRBS 2
23
- 1 or equivalent pattern.
Specifications at -40°C are guaranteed by design and characterization.
Excluding I
BIAS
and I
MOD
. Input data is AC-coupled. TX_FAULT open, SHUTDOWN open.
Power-supply noise rejection (PSNR) = 20log
10
(V
noise (on VCC
) /
ΔV
OUT
). V
OUT
is the voltage across the 15Ω load when IN+
is high.
The minimum required voltage at the OUT+ and OUT- pins is +0.75V.
Guaranteed by design and characterization.
Tested with 00001111 pattern at 2.7Gbps.
DJ includes pulse-width distortion (PWD).
_______________________________________________________________________________________
3
155Mbps to 4.25Gbps SFF/SFP Laser Driver
with Extinction Ratio Control
MAX3738
Typical Operating Characteristics
(V
CC
= +3.3V, C
APC
= 0.01µF, I
BIAS
= 20mA, I
MOD
= 30mA, T
A
= +25°C, unless otherwise noted.)
OPTICAL EYE DIAGRAM
(2.7Gbps, 2
7
- 1 PRBS, 2.3GHz FILTER)
MAX3738 toc01
OPTICAL EYE DIAGRAM
(1.25Gbps, 2
7
- 1 PRBS, 940MHz FILTER)
MAX3738 toc02
ELECTRICAL EYE DIAGRAM
(I
MOD
= 30mA, 2.7Gbps, 2
7
- 1 PRBS)
MAX3738 toc03
1310nm FP LASER
r
e
= 8.2dB
1310nm FP LASER
r
e
= 8.2dB
1pF BETWEEN OUT+
AND OUT-
75mV/div
54ps/div
116ps/div
52ps/div
ELECTRICAL EYE DIAGRAM
(I
MOD
= 30mA, 3.125Gbps, 2
7
- 1 PRBS)
MAX3738 toc04
ELECTRICAL EYE DIAGRAM
(I
MOD
= 30mA, 4.25Gbps, 2
7
- 1 PRBS)
MAX3738 toc05
SUPPLY CURRENT (I
CC
) vs. TEMPERATURE
(EXCLUDES BIAS AND MODULATION CURRENTS)
MAX3738 toc06
60
55
SUPPLY CURRENT (mA)
50
45
2.97V
40
35
30
3.3V
3.63V
46ps/div
34ps/div
-40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90
TEMPERATURE (°C)
BIAS-CURRENT MONITOR RATIO
vs. TEMPERATURE
MAX3738 toc07
PHOTOCURRENT MONITOR RATIO
vs. TEMPERATURE
MAX3738 toc08
MODULATION CURRENT vs. R
MODSET
80
70
60
I
MOD
(mA)
50
40
30
20
10
0
MAX3738 toc09
90
88
86
I
BIAS
/I
BC_MON
(mA/mA)
84
82
80
78
76
74
72
70
1.20
1.15
I
MD
/I
PC_MON
(mA/mA)
1.10
1.05
1.00
0.95
0.90
0.85
0.80
90
-40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90
TEMPERATURE (°C)
-40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90
TEMPERATURE (°C)
1
10
R
MODSET
(kΩ)
100
4
_______________________________________________________________________________________
155Mbps to 4.25Gbps SFF/SFP Laser Driver
with Extinction Ratio Control
Typical Operating Characteristics (continued)
(V
CC
= +3.3V, C
APC
= 0.01µF, I
BIAS
= 20mA, I
MOD
= 30mA, T
A
= +25°C, unless otherwise noted.)
DETERMINISTIC JITTER
vs. MODULATION CURRENT
MAX3738 toc10
MAX3738
PHOTODIODE CURRENT vs. R
APCSET
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
0.1
1
R
APCSET
(kΩ)
10
100
DJ (ps
P-P
)
I
MD
(mA)
50
45
40
35
30
25
20
15
10
5
0
0
10
2.7Gbps
20
30
40
50
60
70
80
90
I
MOD
(mA)
RANDOM JITTER
vs. MODULATION CURRENT
1.8
1.6
1.4
RJ (ps
RMS
)
1.2
1.0
0.8
0.6
0.4
0.2
0
0
10
20
30
40
50
60
70
80
90
I
MOD
(mA)
K (mA/mA)
MAX3738 toc12
COMPENSATION (K) vs. R
MODBCOMP
MAX3738 toc13
2.0
10
1
0.1
0.01
0.001
0.01
0.1
1
10
100
R
MODBCOMP
(kΩ)
TEMPERATURE COMPENSATION vs.
R
TH_TEMP
(R
MODTCOMP
= 500Ω)
MAX3738 toc14
TEMPERATURE COMPENSATION vs.
R
TH_TEMP
(R
MODTCOMP
= 10kΩ)
MAX3738 toc15
100
90
80
I
MOD
(mA)
R
TH_TEMP
= 12kΩ
R
TH_TEMP
= 7kΩ
70
60
50
40
30
-10 0
R
TH_TEMP
= 4kΩ
R
TH_TEMP
= 2kΩ
44
42
40
I
MOD
(mA)
38
36
34
32
30
R
TH_TEMP
= 12kΩ
R
TH_TEMP
= 7kΩ
R
TH_TEMP
= 4kΩ
R
TH_TEMP
= 2kΩ
10 20 30 40 50 60 70 80 90
TEMPERATURE (°C)
-10 0 10 20 30 40 50 60 70 80 90 100
TEMPERATURE (°C)
_______________________________________________________________________________________
MAX3738 toc11
5
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