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19-1249; Rev 0b; 10/97
622Mbps LAN/WAN Laser Driver with
Automatic Power Control and Safety Shutdown
________________General Description
The MAX3766 is a complete, easy-to-program laser
driver for fiber optic LAN transmitters, optimized for
operation at 622Mbps. It includes a laser modulator,
automatic power control (APC), and a failure indicator
with latched shutdown.
Laser modulation current can be programmed up to
60mA at 622Mbps. A programmable modulation tem-
perature coefficient can be used to keep the transmit-
ted extinction ratio nearly constant over a wide
temperature range. The modulator operates at data
rates up to 1.25Gbps at reduced modulation current.
APC circuitry uses feedback from the laser’s monitor
photodiode to adjust the laser bias current, producing
constant output power regardless of laser temperature
or age. The MAX3766 supports laser bias currents up
to 80mA.
The MAX3766 provides extensive laser safety features,
including a failure indicator with latched shutdown and
a smooth start-up bias generator. These features help
ensure that the transmitter output does not reach haz-
ardous levels. The MAX3766 is available in a compact
20-pin QSOP and dice.
KIT
ATION
EVALU
BLE
AVAILA
____________________________Features
o
60mA Modulation Current
o
80mA Bias Current
o
200ps Edge Speed
o
Modulation-Current Temperature Compensation
o
Automatic Power Control
o
Laser-Fail Indicator with Latched Shutdown
o
Smooth Laser Start-Up
MAX3766
Ordering Information
PART
MAX3766EEP
MAX3766E/D
TEMP. RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
20 QSOP
Dice*
*Dice
are designed to operate over this range, but are tested and
guaranteed at T
A
= +25°C only. Contact factory for availability.
________________________Applications
622Mbps ATM Transmitters
1.25Gbps Fiber Optic LAN Transmitters
1.25Gbps Ethernet Transmitters
TOP VIEW
BIASMAX 1
TC 2
REF2 3
20 REF1
19 POWERSET
18 MD
17 GNDOUT
Pin Configuration
Typical Application Circuits appear at end of data sheet.
MOD 4
GND 5
IN- 6
IN+ 7
GND 8
V
CC
9
ENABLE 10
MAX3766
16 BIAS
15 OUT+
14 OUT-
13 V
CCOUT
12 FAIL
11 SAFETY
QSOP
________________________________________________________________
Maxim Integrated Products
1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.
For small orders, phone 408-737-7600 ext. 3468.
622Mbps LAN/WAN Laser Driver with
Automatic Power Control and Safety Shutdown
MAX3766
ABSOLUTE MAXIMUM RATINGS
Supply Voltage, V
CC
, V
CCOUT
.................................-0.5V to 7.0V
Voltage at IN+, IN-, ENABLE,
SAFETY,
FAIL
...........................................-0.5V to (V
CC
+ 0.5V)
Voltage at MOD, BIASMAX, POWERSET, TC ..........-0.5V to 4.0V
Current out of REF1, REF2 .................................-0.1mA to 10mA
Current into OUT+, OUT- ....................................-5mA to 100mA
Current into BIAS.................................................-5mA to 130mA
Current into MD .......................................................-5mA to 5mA
Current into
FAIL
...................................................-5mA to 30mA
Current into SAFETY..............................................-5mA to 10mA
Continuous Power Dissipation (T
A
= +85°C)
QSOP (derate 9.1mW/°C above +85°C) .......................590mW
Operating Junction Temperature Range ...........-40°C to +150°C
Processing Temperature (dice) .......................................+400°C
Storage Temperature Range .............................-55°C to +150°C
Lead Temperature (soldering, 10sec) .............................+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
PARAMETER
RECOMMENDED OPERATING CONDITIONS
Supply Voltage, V
CC
Ambient Operating Temperature
Differential Input Signal Amplitude
Input Common-Mode Voltage
Enable Input High
Enable Input Low
Voltage at OUT+, OUT-
Voltage at BIAS
FAIL
Load
Data Rate
Data Duty Cycle
Laser to PIN Coupling
DC PARAMETERS
Supply Current
FAIL
Output High
FAIL
Output Low
Bias-Current Range
Bias Current when Driver is
Disabled or Shut Down
Modulation-Current Programmable
Range
Modulation Current
Modulation Current when Driver is
Disabled or Shut Down
Minimum Modulation-Current
Temperature Compensation
Maximum Modulation-Current
Temperature Compensation
R
TC
= 0Ω
R
TC
= open
-50
5600
Input data high (Note 3)
Input data low (Note 2)
2
1
I
CC
(Note 2)
R
F AIL
= 5.1kΩ
I
MD
> 15µA, R
F AIL
= 5.1kΩ
(Note 3)
0.5
0.1
21
4.3
0.33
0.44
80
10
60
200
10
25
32
mA
V
V
mA
µA
mA
µA
µA
ppm/°C
ppm/°C
While using APC
Not tested
All DC testing uses 5.1kΩ load
V
CC
- 2.5
V
CC
- 2.5
2.7 to 20
DC to 1.25
50
0.001 to 0.1
(Note 1)
V
IN+
- V
IN-
, common-mode input =
V
CC
- 1.3V, Figure 1
Referenced to V
CC
4.5
-40
500
-1.4
2.0
0.8
5.0
25
1000
-1.3
5.5
85
1800
-1.19
V
°C
mV
V
V
V
V
V
kΩ
Gbps
%
mA/mA
CONDITIONS
MIN
TYP
MAX
UNITS
2
_______________________________________________________________________________________
622Mbps LAN/WAN Laser Driver with
Automatic Power Control and Safety Shutdown
ELECTRICAL CHARACTERISTICS (continued)
PARAMETER
Monitor-Diode Current
Programmable Range
Monitor-Diode Bias Voltage
Upper MD Voltage for Failure
Lower MD Voltage for Failure
Range of MD for No Failure
REF1 Voltage for Failure
REF1 Reference Voltage
REF2 Reference Voltage
AC PARAMETERS
(Notes 4, 5, and 6)
I
MOD
= 60mA
Output Edge Speed (20% to 80%)
Output Aberrations
Pulse-Width Distortion
Random Jitter
I
MOD
= 30mA
I
MOD
= 10mA
I
MOD
= 30mA
I
MOD
= 60mA
I
MOD
= 30mA
I
MOD
= 10mA
RMS, T
A
= +25°C, V
CC
= +5V, I
MOD
= 30mA
210
160
125
10
5
20
80
2
80
80
120
3
ps
ps
400
300
250
%
ps
V
CC
- V
MD
Referenced to V
CC
Referenced to V
CC
Width of operating window, centered at
nominal V
MD
Referenced to nominal V
REF1
T
A
= +25°C, V
REF1
T
A
= +25°C, V
REF2
0.5
2.8
2.1
3.1
2.4
3.4
2.7
300
CONDITIONS
MIN
15
1.5
-1.2
-2.8
2.1
TYP
MAX
2000
2.3
UNITS
µA
V
V
V
mV
V
V
V
MAX3766
3
Note 1:
Dice are tested at room temperature only (T
A
= +25°C).
Note 2:
V
CC
= +5.5V, R
BIASMAX
= 887Ω, R
MOD
= 887Ω, R
POWERSET
= 287Ω, R
TC
= 0Ω, V
BIAS
= V
OUT+
= V
OUT-
= 3.0V. Supply
current excludes I
BIAS
, I
OUT+
, I
OUT-
, and I
FAIL
.
Note 3:
Total output current must be reduced at high temperatures with packaged product to maintain maximum junction
temperature of T
j
= +150°C. See the
Design Procedure
section.
Note 4:
All AC parameters are measured with a 25Ω load. I
MOD
is the AC current amplitude at either OUT pin. The AC voltage at
OUT is greater than V
CC
- 2.5V.
Note 5:
Pulse-width distortion is measured at the 50% crossing point. Data input is a 155MHz square wave, with t
R
≈
300ps.
Note 6:
AC specifications are guaranteed by design and characterization.
_______________________________________________________________________________________
622Mbps LAN/WAN Laser Driver with
Automatic Power Control and Safety Shutdown
MAX3766
Typical Operating Characteristics
(Typical Operating Characteristics are measured on the MAX3766 evaluation kit, V
CC
= +5.0V, T
A
= +25°C, unless otherwise noted.)
SUPPLY CURRENT vs. TEMPERATURE
(EXCLUDES OUTPUT CURRENTS AND I
FAIL
)
MAX3766-01
MODULATION CURRENT TEMPCO
vs. R
TC
MAX3766-02
DIE MODULATION CURRENT vs. R
MOD
(T
J
= +25°C)
LASER MODULATION CURRENT (mAp-p)
TEMPCO = 3000ppm/°C
TEMPCO = 0ppm/°C
MAX3766-03
40
6000
100
SUPPLY CURRENT (mA)
30
TEMPCO (ppm/°C)
4000
TEMPCO = 5600ppm/°C
10
20
2000
10
0
0
-40
-20
0
20
40
60
80
100
1
10
100
1k
R
TC
(Ω)
10k
100k
1M
AMBIENT TEMPERATURE (°C)
1
1
10
100
1k
10k
100k
R
MOD
(Ω)
MODULATION CURRENT vs. R
MOD
(20 QSOP, T
A
= +25°C)
LASER MODULATION CURRENT (mAp-p)
TEMPCO = 0ppm/°C
MAX3766-04
MODULATION CURRENT
vs. TEMPERATURE
R
TC
= 100Ω
MODULATION CURRENT (mAp-p)
60
R
TC
= 330Ω
50
R
TC
= 1kΩ
R
TC
= 3.3kΩ
40
R
TC
= 10kΩ
R
TC
= 100kΩ
MAX3766-05
MODULATION EDGE SPEED AND
PWD vs. AMPLITUDE
MAX3766-06
100
70
250
20% TO 80% EDGE SPEED (ps)
200
T
A
= +85°C
T
A
= +25°C
TEMPCO = 3000ppm/°C
10
TEMPCO = 5600ppm/°C
150
100
T
A
= -40°C
50
PULSE-WIDTH
DISTORTION (ps)
0
10
20
30
40
50
60
30
1
1
10
100
1k
10k
100k
R
MOD
(Ω)
20
-40
-20
0
20
40
60
80
100
AMBIENT TEMPERATURE (°C)
0
MODULATION CURRENT (mAp-p)
EYE DIAGRAM
(622Mbps, 1300nm LASER, 470MHz FILTER)
MAX3766-07
EYE DIAGRAM
(1.244Gbps, 25Ω LOAD, I
MOD
= 60mA)
2 - 1 PRBS
31
MAX3766-08
MONITOR CURRENT vs. R
POWERSET
MAX3766-09
10
2 - 1 PRBS
31
MD CURRENT (mA)
1
125µW/div
60mA/div
0.1
0.01
161ps/div
81ps/div
0.1
1
10
R
POWERSET
(kΩ)
100
1000
4
_______________________________________________________________________________________
622Mbps LAN/WAN Laser Driver with
Automatic Power Control and Safety Shutdown
Typical Operating Characteristics (continued)
(Typical Operating Characteristics are measured on the MAX3766 evaluation kit, V
CC
= +5.0V, T
A
= +25°C, unless otherwise noted.)
MAX3766
BIAS CURRENT vs. R
BIASMAX
(NO APC, OPEN-LOOP CONFIGURATION)
MAX3766-10
MONITOR CURRENT vs. TEMPERATURE
MAX3766-11
DATA-DEPENDENT JITTER
vs. TEMPERATURE (CMD = 0.1µF)
240
220
DDJ (ps)
200
180
160
140
2 PRBS PATTERN
72 CONSECUTIVE ZEROS
13
MAX3766-12
100
10
260
1
I
BIAS
(mA)
I
MD
(mA)
NOMINAL = 1mA
2
23
- 1 PRBS PATTERN
10
0.1
NOMINAL = 200µA
NOMINAL = 20µA
0.01
NOMINAL = 2µA
1
1
10
100
1k
10k
100k
R
BIASMAX
(Ω)
0.001
-40
-20
0
20
40
60
80
100
AMBIENT TEMPERATURE (°C)
120
100
-40
-20
0
20
40
60
80
100
AMBIENT TEMPERATURE (°C)
UNSUCCESSFUL STARTUP
V
ENABLE
V
MD
FAIL
MAX3766-13
SUCCESSFUL STARTUP
MAX3766-14
SMOOTH STARTUP
MAX3766-15
V
ENABLE
V
MD
FAIL
OPTICAL OUTPUT WITH DATA ON
100µW/
div
V
SAFETY
(τ = 30µs)
V
SAFETY
(τ = 1500µs)
OPTICAL OUTPUT WITH DATA OFF
DATA OUT (AC COUPLED)
DATA OUT (AC COUPLED)
50µs/div
5µs/div
10µs/div
ABRUPT SHUTDOWN
MAX3766-16
REFERENCE VOLTAGE
vs. TEMPERATURE
MAX3766-17
3.40
3.20
3.00
VOLTAGE (V)
2.80
2.60
2.40
2.20
2.00
V
REF2
R
TC
= OPEN
V
REF1
OPTICAL OUTPUT WITH DATA ON
100µW/
div
OPTICAL OUTPUT WITH DATA OFF
5µs/div
-45
-25
-5
20
40
60
80
100
AMBIENT TEMPERATURE (°C)
_______________________________________________________________________________________
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