19-2247; Rev 1; 4/02
2.5Gbps Laser Driver with Automatic
Modulation Control
General Description
The MAX3865 is designed for direct modulation of laser
diodes at data rates up to 2.5Gbps. It incorporates two
feedback loops, the automatic power-control (APC)
loop and the automatic modulation-control (AMC) loop,
to maintain constant average optical output and extinc-
tion ratio over temperature and laser lifetime. External
resistors or current output DACs may set the laser out-
put levels. The driver can deliver up to100mA of laser
bias current and up to 60mA laser modulation current
with a typical (20% to 80%) edge speed of 84ps.
The MAX3865 accepts differential clock and data input
signals with on-chip 50Ω termination resistors. The inputs
can be configured for CML or other high-speed logic. An
input data-retiming latch can be enabled to reject input
pattern-dependent jitter when a clock signal is available.
The MAX3865 provides laser bias current and modulation
current monitors, as well as a failure detector, to indicate
the laser operating status. These features are all imple-
mented on an 81mil
✕
103mil die; the MAX3865 is also
available as a 32-pin QFN package.
o
Single +3.3V or +5V Power Supply
o
68mA Supply Current
o
Up to 2.5Gbps (NRZ) Operation
o
Feedback Control for Constant Average Power
o
Feedback Control for Constant Extinction Ratio
o
Programmable Bias Current Up to 100mA
o
Programmable Modulation Current Up to 60mA
o
84ps Rise/Fall Time
o
Selectable Data Retiming Latch
o
Bias and Modulation Current Monitors
o
Failure Detector
o
ESD Protection
Features
MAX3865
†
Ordering Information
PART
MAX3865EGJ
MAX3865E/D
TEMP. RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
32 QFN
Dice*
Applications
SONET/SDH Transmission Systems
Add/Drop Multiplexers
Digital Cross-Connects
Section Regenerators
2.5Gbps Optical Transmitters
*Dice
are designed to operate from -40°C to +85°C , but are tested
and guaranteed at T
A
= +25°C only. Contact factory for availability.
Pin Configuration appears at end of data sheet.
Typical Applications Circuit
+3.3V
+3.3V
200Ω
200Ω
L
P
BIASMON
MODMON
RTEN
EN0
EN1
FAIL
V
CC
MODN
L
P
0.056µF
20Ω
15Ω
MODQ
20Ω
0.056µF
LED
20Ω
LASER
+3.3V
DATA-
DATA+
50Ω
50Ω
+3.3V
50Ω
50Ω
DATA-
DATA+
V
DR
V
CR
CLK+
CLK-
GND
MAX3892
2.5Gbps SERIALIZER
CLK+
CLK-
MAX3865
BIAS
BIAS_X
MD
MD_X
MODMAX
BIASMAX
AMCSET
APCSET
REPRESENTS A CONTROLLED-IMPEDANCE
TRANSMISSION LINE
R
MODMAX
R
BIASMAX
R
APCSET
R
AMCSET
†
Covered by U.S. Patent numbers 5,883,910, 5,850,409, and other patent pending.
________________________________________________________________
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.
2.5Gbps Laser Driver with Automatic
Modulation Control
MAX3865
ABSOLUTE MAXIMUM RATINGS
Voltage at Any Pin...............................................................+7.0V
Supply Voltage (V
CC
) ............................................-0.5V to +7.0V
Voltage at V
CR
, V
DR
, DATA+, DATA-,
CLOCK+, and CLOCK- Pins ..................-0.5V to (V
CC
+ 0.5V)
Voltage at DATA+ and
DATA- Pins ..................................(V
DR
- 1.2V) to (V
DR
+ 1.2V)
Voltage at CLK+ and CLK- Pins ......(V
CR
- 1.2V) to (V
CR
+ 1.2V)
Voltage at MODQ and MODN Pins ................0V to (V
CC
+ 1.5V)
Voltage at Any Other Pins (RTEN, EN0, EN1,
FAIL,
MODMAX, BIASMAX, AMCSET, APCSET, MD_X, BIAS,
BIAS_X, BIASMON, MODMON) ............-0.5V to (V
CC
+ 0.5V)
Current into BIAS Pin ......................................-20mA to +150mA
Current into MODQ and MODN Pins ..............-20mA to +100mA
Current into MD Pin...........................................-10mA to +10mA
Operating Junction Temperature .....................-55°C to +150°C
Storage Temperature Range .............................-55°C to +150°C
Continuous Power Dissipation (T
A
= +85°C)
32-Pin QFN (derate 21.2mW/°C above +85°C) ................1.3W
Lead Temperature (soldering, 10s) .................................+300°C
Processing Temperature (die) .........................................+400°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
= +3.14V to +3.6V or +4.5V to +5.5V, T
A
= -40°C to +85°C. Typical values are at V
CC
= +3.3V, I
BIAS
= 50mA, I
MOD
= 30mA,
T
A
= +25°C, unless otherwise noted.) (Notes 1, 2, 3)
PARAMETER
Power-Supply Current
Differential Input Voltage
Instantaneous Input Voltage
Single-Ended Input Resistance
Input Return Loss, for Data+,
Data-, Clock+, and Clock-
Bias-Current Setting Range
Bias Off Current
Bias-Current Setting Accuracy
Compliance Voltage for BIAS
and BIAS_X
I
BIAS
to I
BIASMON
Ratio
Modulation-Current Setting
Range
Modulation Off Current
Modulation-Current Setting
Accuracy
Compliance Voltage for MODQ
and MODN
I
MOD
to I
MODMON
Ratio
Compliance Voltage for
BIASMON and MODMON
Voltage at MD Pin
V
MD
(Note 5)
1.8
1.0
I
MOD
EN0, EN1 = low
AMC off
I
MOD
= 60mA
I
MOD
= 5mA
+3.14V
≤
V
CC
≤
+3.6V
+4.5V
≤
V
CC
≤
+5.5V
1.8
1.8
32
V
CC
+
0.4
±0.25
V
CC
+
1.2
5.5
5
EN0, EN1 = low
APC off
(Note 5)
I
BIAS
= 100mA
I
BIAS
= 1mA
1
48
60
0.1
±15
±0.1
V
CC
+
0.4
RL
IN
SYMBOL
I
CC
V
ID
CONDITIONS
V
CC
= +3.14V to +3.6V (Note 4)
V
CC
= +4.5V to +5.5V,
typical current at V
CC
= +5.0V (Note 4)
Data and clock inputs (Figure 2)
Data and clock inputs (Figure 2) (Note 5)
Input to V
DR
, V
CR
f
≤
2.7GHz
2.7GHz < f < 4GHz
1
0.2
1.3
40
50
20
17
100
0.1
±15
MIN
TYP
68
69
MAX
85
90
1.6
V
CC
+
0.4V
60
mA
Vp-p
V
Ω
dB
mA
mA
%
mA
V
m
A/mA
UNITS
mA
mA
%
mA
V
m
A/mA
(Note 5)
V
V
2
_______________________________________________________________________________________
2.5Gbps Laser Driver with Automatic
Modulation Control
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= +3.14V to +3.6V or +4.5V to +5.5V, T
A
= -40°C to +85°C. Typical values are at V
CC
= +3.3V, I
BIAS
= 50mA, I
MOD
= 30mA,
T
A
= +25°C, unless otherwise noted.) (Notes 1, 2, 3)
PARAMETER
Bias-Setting Accuracy at
MD Pin
Modulation-Setting
Accuracy at MD Pin
EN0, EN1, and RTEN Input High
EN0, EN1, and RTEN Input Low
FAIL
Output High
FAIL
Output Low
FAIL
Current
Setup/Hold Time
Output Edge Speed
Output Overshoot
Enable/Startup
Maximum CID
Deterministic Jitter
Random Jitter
AMC Pilot Tone Frequency
f
AMC
t
SU
, t
HD
t
R
, t
F
Source 50µA
Sink 100µA
Low state, V
OL
forced to V
CC
(Figure 2) (Note 5)
Load = 20Ω, 20% to 80% (Notes 5, 7)
(Notes 5, 7)
APC and AMC off
(Notes 2, 5)
(Notes 2, 5)
(Notes 5, 7)
80
22
1.6
1
50
100
84
9
150
130
2.4
0.4
5.0
SYMBOL
I
MD
= 1mA
I
MD
= 36µA
(Note 6)
I
MD
= 1mA
I
MD
= 36µA
2.0
0.8
CONDITIONS
MIN
TYP
±15
±10
±15
±10
MAX
UNITS
%
µA
%
µA
V
V
V
V
mA
ps
ps
%
ns
bit
psp-p
ps
RMS
MHz
MAX3865
Note 1:
Note 2:
Note 3:
Note 4:
Note 5:
Note 6:
Note 7:
AC characterization performed using the circuit in Figure 1.
Measured using a 2.5Gbps 2
13
- 1 PRBS with 80 0’s and 80 1’s input data pattern.
Specifications at -40°C are guaranteed by design and characterization.
V
CC
current excludes the current into MODQ, MODN, BIAS, BIAS_X, MODMON, and BIASMON pins.
Guaranteed by design and characterization.
Measured with low-frequency data. Instantaneous current into MD pin range is 36µA to 1000µA.
Measured using a 2.5Gbps repeating 0000 0000 1111 1111 pattern.
_______________________________________________________________________________________
3
2.5Gbps Laser Driver with Automatic
Modulation Control
MAX3865
V
CC
V
CC
33Ω
0.1µF
MODN
DATA+
PATTERN GENERATOR
CLK+-
50Ω
V
CC
50Ω
DATA+
V
DR
V
CR
CLK+
MODQ
33Ω
0.1µF
50Ω
RTEN
DATA-
50Ω
DATA-
V
CC
OSCILLOSCOPE
MAX3865
BIAS
50Ω
V
CC
CLK-
50Ω
CLK-
BIAS_X
V
CC
GND
EN1
EN0
Figure 1. Test Circuit
V
CC
+ 0.4V
CLK+
0.1V–0.8V
CLK-
1.3V
t
SU
DATA+
t
HD
V
CC
+ 0.4V
0.1V–0.8V
DATA-
1.3V
(DATA+) - (DATA-)
V
ID
= 0.2Vp-p–1.6Vp-p
I
MODQ
5mA–60mA
Figure 2. Required Input Signal, Setup/Hold-Time Definition, and Output Polarity
4
_______________________________________________________________________________________
2.5Gbps Laser Driver with Automatic
Modulation Control
Typical Operating Characteristics
(T
A
= +25°C, unless otherwise noted.)
OPTICAL EYE DIAGRAM
(EXTINCTION RATIO = 8.25dB,
2
13
-1 PRBS AT 2.5Gbps, 1.87GHz FILTER)
MAX3865 toc01
MAX3865
ELECTRICAL EYE DIAGRAM
(I
MODQ
= 60mA)
MAX3865 toc02
ELECTRICAL EYE DIAGRAM
(I
MODQ
= 30mA)
MAX3865 toc03
PATTERN 2
13
- 1 PRBS
DATA RATE = 2.5Gbps
PATTERN 2
13
- 1 PRBS
DATA RATE = 2.5Gbps
58ps/div
58ps/div
58ps/div
SUPPLY CURRENT (I
CC
) vs. TEMPERATURE
(EXCLUDES BIAS AND MODULATION CURRENTS)
MAX3865 toc04
DETERMINISTIC JITTER
vs. TEMPERATURE (I
MODQ
= 60mA)
MAX3865 toc05
TYPICAL DISTRIBUTION OF RISE TIME
(WORST-CASE CONDITIONS)
ELECTRICAL
MEASUREMENT
I
MODQ
= 60mA
V
CC
= +3.14V
T
A
= +85°C
MAX 3865 toc06
80
75
SUPPLY CURRENT (mA)
70
65
60
55
50
-40
-15
10
35
60
V
CC
= +5.0V
V
CC
= +3.3V
100
90
DETERMINISTIC JITTER (ps)
80
70
60
50
40
30
20
10
0
30
25
PERCENT OF UNITS (%)
20
15
10
5
0
85
-40
-20
0
20
40
60
80
100 102 104 106 108 110 112 114 116 118 120
RISE TIME (ps)
TEMPERATURE (°C)
TEMPERATURE (°C)
TYPICAL DISTRIBUTION OF FALL TIME
(WORST-CASE CONDITIONS)
MAX 3865 toc07
DIFFERENTIAL |S11| vs. FREQUENCY
-17
-19
-21
|S11| (dB)
-23
-25
-27
-29
-31
-33
MAX3865 toc08
30
25
PERCENT OF UNITS (%)
20
15
10
5
0
100 102 104 106 108 110 112 114 116 118 120
FALL TIME (ps)
ELECTRICAL
MEASUREMENT
I
MODQ
= 60mA
V
CC
= +3.14V
T
A
= +85°C
-15
-35
0
500 1000 1500 2000 2500 3000 3500 4000
FREQUENCY (MHz)
_______________________________________________________________________________________
5
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