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MAX3766EEP
Datasheet
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Maxim MAX3766E-D, MAX3766EEP Datasheet

________________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 tem­perature coefficient can be used to keep the transmit­ted 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 haz­ardous levels. The MAX3766 is available in a compact 20-pin QSOP and dice.
________________________Applications
622Mbps ATM Transmitters
1.25Gbps Fiber Optic LAN Transmitters
1.25Gbps Ethernet Transmitters
____________________________Features
♦ 60mA Modulation Current ♦ 80mA Bias Current ♦ 200ps Edge Speed ♦ Modulation-Current Temperature Compensation ♦ Automatic Power Control ♦ Laser-Fail Indicator with Latched Shutdown ♦ Smooth Laser Start-Up
MAX3766
622Mbps LAN/WAN Laser Driver with
Automatic Power Control and Safety Shutdown
________________________________________________________________
Maxim Integrated Products
1
19-1249; Rev 0b; 10/97
PART
MAX3766EEP MAX3766E/D -40°C to +85°C
-40°C to +85°C
TEMP. RANGE PIN-PACKAGE
20 QSOP Dice*
EVALUATION KIT
AVAILABLE
Ordering Information
*
Dice are designed to operate over this range, but are tested and
guaranteed at T
A
= +25°C only. Contact factory for availability.
Typical Application Circuits appear at end of data sheet.
Pin Configuration
20 19 18 17 16 15 14 13
1 2 3 4 5 6 7 8
REF1 POWERSET MD GNDOUTMOD
REF2
TC
BIASMAX
TOP VIEW
BIAS OUT+ OUT­V
CCOUT
GND
IN+
IN-
GND
12 11
9
10
FAIL SAFETYENABLE
V
CC
MAX3766
QSOP
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.
MAX3766
622Mbps LAN/WAN Laser Driver with Automatic Power Control and Safety Shutdown
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
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.
Supply Voltage, VCC, V
CC
OUT
.................................-0.5V to 7.0V
Voltage at IN+, IN-, ENABLE,
SAFETY,
FAIL ...........................................-0.5V to (VCC+ 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
CONDITIONS UNITSMIN TYP MAXPARAMETER
V4.5 5.0 5.5Supply Voltage, V
CC
(Note 1) °C-40 25 85Ambient Operating Temperature
Referenced to V
CC
V-1.4 -1.3 -1.19Input Common-Mode Voltage
V0.8Enable Input Low
V
IN+
- V
IN-
, common-mode input =
VCC- 1.3V, Figure 1
V2.0Enable Input High
mV500 1000 1800Differential Input Signal Amplitude
VVCC- 2.5Voltage at BIAS
While using APC %50Data Duty Cycle
GbpsDC to 1.25Data Rate
VVCC- 2.5Voltage at OUT+, OUT-
Not tested mA/mA0.001 to 0.1Laser to PIN Coupling
R
F AIL
= 5.1kΩ V4.3
FAIL Output High
(Note 3) mA0.5 80Bias-Current Range
ICC(Note 2)
IMD> 15µA, R
F AIL
= 5.1kΩ V0.33 0.44
FAIL Output Low
mA21 25 32Supply Current
µA0.1 10
Bias Current when Driver is Disabled or Shut Down
Input data low (Note 2) µA1 200Modulation Current
Input data high (Note 3) mA2 60
Modulation-Current Programmable Range
RTC= 0Ω ppm/°C-50
Minimum Modulation-Current Temperature Compensation
µA10
Modulation Current when Driver is Disabled or Shut Down
All DC testing uses 5.1kΩ load kΩ2.7 to 20
FAIL Load
RTC= open ppm/°C5600
Maximum Modulation-Current Temperature Compensation
RECOMMENDED OPERATING CONDITIONS
DC PARAMETERS
MAX3766
622Mbps LAN/WAN Laser Driver with
Automatic Power Control and Safety Shutdown
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
Note 1: Dice are tested at room temperature only (TA= +25°C). Note 2: V
CC
= +5.5V, R
BIASMAX
= 887Ω, R
MOD
= 887Ω, R
POWERSET
= 287Ω, RTC= 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 tR≈ 300ps.
Note 6: AC specifications are guaranteed by design and characterization.
V
CC
- V
MD
V1.5 2.1 2.3Monitor-Diode Bias Voltage
Referenced to V
CC
V-2.8Lower MD Voltage for Failure
Referenced to V
CC
V-1.2Upper MD Voltage for Failure
Referenced to nominal V
REF1
V0.5REF1 Voltage for Failure
TA= +25°C, V
REF2
V2.1 2.4 2.7REF2 Reference Voltage
Width of operating window, centered at nominal V
MD
TA= +25°C, V
REF1
V
CONDITIONS
2.8 3.1 3.4REF1 Reference Voltage
mV300Range of MD for No Failure
I
MOD
= 60mA 210 400
Output Edge Speed (20% to 80%)
I
MOD
= 10mA
ps
125 250
I
MOD
= 30mA 160 300
I
MOD
= 30mA %10Output Aberrations
µA15 2000
Monitor-Diode Current Programmable Range
UNITSMIN TYP MAXPARAMETER
I
MOD
= 60mA 5 80
I
MOD
= 30mA 20 80
I
MOD
= 10mA
ps
80 120
Pulse-Width Distortion
RMS, TA= +25°C, VCC= +5V, I
MOD
= 30mA ps2 3Random Jitter
AC PARAMETERS (Notes 4, 5, and 6)
MAX3766
622Mbps LAN/WAN Laser Driver with Automatic Power Control and Safety Shutdown
4 _______________________________________________________________________________________
Typical Operating Characteristics
(Typical Operating Characteristics are measured on the MAX3766 evaluation kit, VCC= +5.0V, TA = +25°C, unless otherwise noted.)
0
20
10
30
40
-40 0
20
-20 40
60
80 100
SUPPLY CURRENT vs. TEMPERATURE
(EXCLUDES OUTPUT CURRENTS AND I
FAIL
)
MAX3766-01
AMBIENT TEMPERATURE (°C)
SUPPLY CURRENT (mA)
6000
4000
1 1k10 100 10k 100k 1M
MODULATION CURRENT TEMPCO
vs. R
TC
MAX3766-02
RTC (Ω)
TEMPCO (ppm/°C)
0
2000
100
1
1 1k10
100
10k
100k
DIE MODULATION CURRENT vs. R
MOD
(TJ = +25°C)
MAX3766-03
R
MOD
(Ω)
LASER MODULATION CURRENT (mAp-p)
10
TEMPCO = 0ppm/°C
TEMPCO = 5600ppm/°C
TEMPCO = 3000ppm/°C
100
1
1 1k10 100 10k 100k
MODULATION CURRENT vs. R
MOD
(20 QSOP, TA = +25°C)
MAX3766-04
R
MOD
(Ω)
LASER MODULATION CURRENT (mAp-p)
10
TEMPCO = 0ppm/°C
TEMPCO = 3000ppm/°C
TEMPCO = 5600ppm/°C
125µW/div
161ps/div
EYE DIAGRAM
(622Mbps, 1300nm LASER, 470MHz FILTER)
MAX3766-07
231- 1 PRBS
20
30
40
50
60
70
-40 0
20
-20 40
60
80 100
MODULATION CURRENT
vs. TEMPERATURE
MAX3766-05
AMBIENT TEMPERATURE (°C)
MODULATION CURRENT (mAp-p)
RTC = 100Ω
RTC = 330Ω
RTC = 1kΩ
RTC = 3.3kΩ
RTC = 10kΩ
RTC = 100kΩ
0
50
100
150
200
250
0 3010 20
40
50 60
MODULATION EDGE SPEED AND
PWD vs. AMPLITUDE
MAX3766-06
MODULATION CURRENT (mAp-p)
20% TO 80% EDGE SPEED (ps)
TA = +85°C
TA = +25°C
TA = -40°C
PULSE-WIDTH
DISTORTION (ps)
60mA/div
81ps/div
EYE DIAGRAM
(1.244Gbps, 25Ω LOAD, I
MOD
= 60mA)
MAX3766-08
231- 1 PRBS
0.01
10.1 10 100 1000
MONITOR CURRENT vs. R
POWERSET
MAX3766-09
R
POWERSET
(kΩ)
MD CURRENT (mA)
0.1
1
10
MAX3766
622Mbps LAN/WAN Laser Driver with
Automatic Power Control and Safety Shutdown
_______________________________________________________________________________________
5
100
1 1k10 100 10k 100k
BIAS CURRENT vs. R
BIASMAX
(NO APC, OPEN-LOOP CONFIGURATION)
MAX3766-10
R
BIASMAX
(Ω)
I
BIAS
(mA)
1
10
10
0.001
-40 -20 0 20 40 60 80 100
MONITOR CURRENT vs. TEMPERATURE
0.01
MAX3766-11
AMBIENT TEMPERATURE (°C)
I
MD
(mA)
0.1
1
NOMINAL = 1mA
NOMINAL = 200µA
NOMINAL = 20µA
NOMINAL = 2µA
100
260 240 220 200 180 160
140
120
DATA-DEPENDENT JITTER
vs. TEMPERATURE (CMD = 0.1µF)
MAX3766-12
AMBIENT TEMPERATURE (°C)
DDJ (ps)
-40 -20 0 20 40 60 80 100
2
13
PRBS PATTERN
72 CONSECUTIVE ZEROS
223- 1 PRBS PATTERN
10µs/div
UNSUCCESSFUL STARTUP
MAX3766-13
V
ENABLE
V
MD
V
SAFETY
(τ = 30µs)
FAIL
DATA OUT (AC COUPLED)
5µs/div
100µW/
div
ABRUPT SHUTDOWN
MAX3766-16
OPTICAL OUTPUT WITH DATA ON
OPTICAL OUTPUT WITH DATA OFF
50µs/div
SUCCESSFUL STARTUP
MAX3766-14
V
ENABLE
V
MD
FAIL
V
SAFETY
(τ = 1500µs)
DATA OUT (AC COUPLED)
5µs/div
100µW/
div
SMOOTH STARTUP
MAX3766-15
OPTICAL OUTPUT WITH DATA ON
OPTICAL OUTPUT WITH DATA OFF
2.00
2.80
2.60
2.40
2.20
3.20
3.00
3.40
-45 -5
20
-25 40
60
80 100
REFERENCE VOLTAGE
vs. TEMPERATURE
MAX3766-17
AMBIENT TEMPERATURE (°C)
VOLTAGE (V)
RTC = OPEN
V
REF1
V
REF2
Typical Operating Characteristics (continued)
(Typical Operating Characteristics are measured on the MAX3766 evaluation kit, VCC= +5.0V, TA = +25°C, unless otherwise noted.)
MAX3766
622Mbps LAN/WAN Laser Driver with Automatic Power Control and Safety Shutdown
6 _______________________________________________________________________________________
Pin Description
ENABLE is a TTL-compatible input. When low or open, this pin disables the output modulation and bias current.
ENABLE10
A capacitor to ground at SAFETY determines the turn-on delay for the safety circuits. If SAFETY is grounded or TTL low, internal safety shutdown features are disabled. A TTL high at SAFETY enables the internal safety shutdown features.
SAFETY11
The FAIL output asserts low if the voltage at MD is above or below nominal. FAIL also asserts if REF1 is inadvertently tied to the positive supply. FAIL has TTL-compatible output voltage levels.
FAIL
12
Supply Voltage for the Output Current DriversV
CCOUT
13
Inverting Modulation-Current OutputOUT-14
Ground. All grounds must be connected.GND5, 8 Inverting Data InputIN-6 Noninverting Data InputIN+7 Positive Supply Voltage. All VCCpins must be connected.V
CC
9
The current into MOD programs the laser modulation current. Connect MOD to REF2 with a resistor or potentiometer.
MOD4
REF2 is the reference voltage used to program the modulation current. The tempco of REF2 is pro­grammed by RTC.
REF23
PIN
The resistance (RTC) between TC and REF1 programs the temperature coefficient of REF2. Connecting TC directly to REF1 produces the minimum tempco. Leaving TC unconnected produces the maximum tempco.
TC2
The current into BIASMAX sets the maximum laser bias current. Connecting BIASMAX directly to REF1 allows the largest possible bias current.
BIASMAX1
FUNCTIONNAME
Ground for the Output Current DriversGNDOUT17 Input for the laser monitor photodiode current. MD18 The current into POWERSET programs the average optical output power when automatic power
control is used.
POWERSET19
REF1 is a voltage reference used to program laser bias current and average power.REF120
Noninverting Modulation-Current OutputOUT+15 Connection for the DC Laser Bias CurrentBIAS16
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