+3.3V, 2.5Gbps SDH/SONET Laser Driver with Automatic Power Control

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+3.3V, 2.5Gbps SDH/SONET Laser Driver with Automatic Power Control

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19-4769; 9/98
+3.3V, 2.5Gbps SDH/SONET Laser Driver with Automatic Power Control
Single +3.3V Power Supply 62mA Supply Current +3.3V Programmable Modulation Current from 60mA Programmable Bias Current from 100mA Rise/Fall Time 90ps Automatic Average Power Control with Failure Monitor Complies with ANSI, ITU, Bellcore SDH/SONET Specifications Enable Control
MAX3867
MAX3867 complete, single +3.3V laser driver SDH/SONET applications 2.5Gbps. device accepts differential PECL data clock inputs provides bias modulation currents driving laser. synchronizing input latch bypassed clock signal available. automatic power control (APC) feedback loop incorporated maintain constant average optical power over temperature lifetime. wide modulation current range 60mA bias current 100mA easy program, making this product ideal various SDH/SONET applications. MAX3867 also provides enable control, programmable slow-start circuit laser turn-on delay, failure-monitor output indicate when loop unable maintain average optical power. MAX3867 available small 48-pin TQFP package well dice.
Ordering Information
PART MAX3867ECM MAX3867E/D TEMP. RANGE -40°C +85°C -40°C +85°C PIN-PACKAGE TQFP Dice*
Applications
SONET/SDH Transmission Systems Add/Drop Multiplexers Digital Cross-Connects Section Regenerators 2.5Gbps Optical Transmitters
*Dice designed operate over this range, tested guaranteed +25°C only. Contact factory availability.
Configuration appears data sheet.
Typical Operating Circuit
+3.3V ENABLE LATCH +3.3V FAIL *FERRITE BEAD 0.056µF SERIALIZER WITH CLOCK GEN. 84.5 84.5 84.5 84.5 CLK+ CLKMD BIASMAX MODSET APCFILT APCSET CAPC 1000pF
DATA+
OUTOUT+
MAX3890
DATA-
MAX3867
BIAS
Maxim Integrated Products
free samples latest literature: http://www.maxim-ic.com, phone 1-800-998-8800. small orders, phone 1-800-835-8769.
+3.3V, 2.5Gbps SDH/SONET Laser Driver with Automatic Power Control MAX3867
ABSOLUTE MAXIMUM RATINGS
Supply Voltage, VCC. -0.5V +7.0V Current into BIAS .-20mA +150mA Current into OUT+, OUT- .-20mA +100mA Current into MD.-5mA +5mA Voltage DATA+, DATA-, CLK+, CLK-, ENABLE, LATCH, FAIL, SLWSTRT.-0.5V (VCC 0.5V) Voltage APCFILT, CAPC, MODSET, BIASMAX, APCSET .-0.5V +3.0V Voltage OUT+, OUT-.+1.5V (VCC 1.5V) Voltage BIAS .+1.0V (VCC 0.5V) Current into FAIL .-10mA +30mA Continuous Power Dissipation +85°C) TQFP (derate 20.8mW/°C above +85°C) .1354mW Storage Temperature Range .-65°C +165°C Operating Junction Temperature Range .-55°C +150°C Processing Temperature (die) .+400°C Lead Temperature (soldering, 10sec) .+300°C
Stresses beyond those listed under "Absolute Maximum Ratings" cause permanent damage device. These stress ratings only, functional operation device these other conditions beyond those indicated operational sections specifications implied. Exposure absolute maximum rating conditions extended periods affect device reliability.
ELECTRICAL CHARACTERISTICS
(VCC +3.14V +5.5V, -40°C +85°C. Typical values +3.3V, IMOD 30mA, IBIAS 60mA, +25°C, unless otherwise noted.) (Note PARAMETER Supply Current Bias Current Range Bias Current Bias-Current Stability Bias-Current Absolute Accuracy Differential Input Voltage Common-Mode Input Voltage Clock Data Input Current Input High Voltage (ENABLE, LATCH) Input Voltage (ENABLE, LATCH) Output High Voltage FAIL Output Voltage FAIL Monitor-Diode Reverse Bias Voltage Monitor-Diode Current Range Monitor-Diode Bias Setpoint Stability Monitor-Diode Bias Absolute Accuracy Note Note Note Note Note Note (Note (Note 18µA Sourcing 50µA Sinking 100µA -480 1000 (Note VICM SYMBOL IBIAS IBIAS-OFF (Note (Note ENABLE (Note open loop, IBIAS 100mA open loop, IBIAS open loop Figure PECL compatible 1.49 0.44 1.32 1600 VID/4 CONDITIONS UNITS ppm/°C mVp-p ppm/°C
Characteristics -40°C guaranteed design characterization. Dice tested +25°C only. Tested RMODSET 2.49k, RBIASMAX 1.69k, excluding IBIAS IMOD. Voltage BIAS (VCC 1.6V). Both bias modulation currents will switched current pins grounded. Accuracy refers part-to-part variation. Assuming that laser monitor-diode transfer function does change with temperature.
+3.3V, 2.5Gbps SDH/SONET Laser Driver with Automatic Power Control
ELECTRICAL CHARACTERISTICS
(VCC +3.14V +5.5V, load shown Figure -40°C +85°C. Typical values +3.3V, IMOD 30mA, +25°C.) (Note PARAMETER Input Latch Setup Time Input Latch Hold Time Modulation-Current Range Modulation-Off Current Modulation-Current Stability Modulation-Current Absolute Accuracy Output Rise Time Output Fall Time Output Aberrations Enable/Start-Up Delay Maximum Consecutive Identical Digits Pulse-Width Distortion Jitter Generation (Notes Jitter 12kHz 20MHz, pattern SYMBOL IMOD IMOD-OFF ENABLE (Note IMOD 60mA IMOD (Note (Note (Note (Note MAX3867ECM MAX3867C/D MAX3867ECM MAX3867C/D (Note -480 CONDITIONS LATCH high, Figure LATCH high, Figure UNITS ppm/°C bits psp-p
MAX3867
Note characteristics guaranteed design characterization. Note Measured with 622Mbps pattern, LATCH high. Note (wider pulse narrower pulse) Note Typical Operating Characteristics worst-case distribution.
+3.3V, 2.5Gbps SDH/SONET Laser Driver with Automatic Power Control MAX3867
DATA+ DATA100mV 800mV 200mVp-p
(DATA+) (DATA-) IOUT+
1600mVp-p
IMOD
Figure Required Input Signal Output Polarity
tCLK 402ps
FERRITE BEADS BLM11A601S MURATA ELECTRONICS BLM21A102S MURATA ELECTRONICS
0.056µF
MAX3867
OUT0.5pF OUT+ 0.056µF BIAS OSCILLOSCOPE
DATA
Figure Setup/Hold Time Definition
COMPENSATE PACKAGE LEADS, USED DIE.
Figure Output Termination Characterization
+3.3V, 2.5Gbps SDH/SONET Laser Driver with Automatic Power Control
Typical Operating Characteristics
(VCC +3.3V, load shown Figure +25°C, unless otherwise noted.)
DIAGRAM (2.488Gbps, 1300nm LASER, 1.87GHz FILTER, 48-TQFP)
MAX3867-01
MAX3867
TYPICAL DISTRIBUTION FALL TIME
MAX3867-02a
DISTRIBUTION FALL TIME (WORST-CASE CONDITIONS)
PERCENT UNITS MEAN 111.6ps 2.9ps 48-TQFP IMOD 30mA +3.14V +85°C
MAX3867-03a
PERCENT UNITS MEAN 88ps 3.0ps 48-TQFP IMOD 30mA
50ps/div
FALL TIME (ps)
FALL TIME (ps)
ELECTRICAL DIAGRAM
MAX3867-04a
ELECTRICAL DIAGRAM
MAX3867-05a
RANDOM JITTER IMOD
MAX3867 toc05
0.022 0.020 RANDOM JITTER (UIp-p) 0.018 0.016 0.014 0.012 0.010 JITTER 12kHz 20MHz PATTERN
26mV /div PATTERN IMOD 30mA 48-TQFP
55mV /div PATTERN IMOD 60mA 48-TQFP
50ps/div
50ps/div
IMOD (mA)
IBIASMAX RBIASMAX
MAX3867-06
IMOD RMODSET
MAX3867-07
RAPCSET
(mA)
MAX3867-08
RBIASMAX
IMOD (mA)
IBIASMAX (mA)
RMODSET
RAPCSET
+3.3V, 2.5Gbps SDH/SONET Laser Driver with Automatic Power Control MAX3867
Typical Operating Characteristics (continued)
(VCC +3.3V, load shown Figure +25°C, unless otherwise noted.)
SUPPLY CURRENT TEMPERATURE (EXCLUDE IBIAS, IMOD, LOAD)
(ps) (mA) TEMPERATURE (°C) IMOD 30mA IBIAS 45mA +3.3V
MAX3867-09
PULSE-WIDTH DISTORTION IMOD
MAX3867-10
+3.3V
IMOD (mA)
Description
NAME GND2 GND1 VCC1 DATA+ DATACLK+ CLKLATCH ENABLE SLWSTRT FAIL N.C. APCFILT GND4 VCC4 Ground internal reference Ground digital circuits Power supply digital circuits Positive PECL Data Input Negative PECL Data Input Positive PECL Clock Input. Connect latch function used. Negative PECL Clock Input. Leave unconnected latch function used. TTL/CMOS Latch Input. High latched data, direct data. TTL/CMOS Enable Input. High normal operation, disable laser bias modulation currents. capacitor from this ground delays turn-on time laser bias modulation currents. TTL/CMOS output. Indicates failure when low. Connection. Leave unconnected. Connect capacitor (CAPCFILT 0.1µF) from this ground filter noise. Ground output circuitry Power Supply output circuitry FUNCTION
+3.3V, 2.5Gbps SDH/SONET Laser Driver with Automatic Power Control
Description (continued)
NAME BIAS OUT+ OUTMD GND3 VCC3 CAPC APCSET MODSET BIASMAX VCC2 Laser Bias Current Output Positive Modulation-Current Output. IMOD flows through this when input data high. Negative Modulation-Current Output. IMOD flows through this when input data low. Monitor Diode Input. Connect this monitor photodiode anode. capacitor ground required filter high-speed monitor photocurrent. Ground Power Supply capacitor connected from this ground controls dominant pole feedback loop. (CAPC 0.1µF) resistor connected from this ground sets desired average optical power. Connect 100k from this ground used. resistor connected from this ground sets desired modulation current. resistor connected from this ground sets maximum bias current. function subtract from this maximum value, Power Supply internal reference FUNCTION
MAX3867
_Detailed Description
MAX3867 laser driver consists main parts: high-speed modulation driver laser-biasing block with Automatic Power Control (APC). circuit design optimized both high-speed low-voltage (+3.3V) operation. minimize pattern-dependent jitter input signal speeds high 2.5Gbps, device accepts differential PECL clock signal data retiming. When LATCH high, input data synchronized clock signal. When LATCH low, input data directly applied output stage. output stage composed high-speed differential pair programmable modulation current source. Since modulation output drives maximum current 60mA into laser with edge speed 100ps, large transient voltage spikes generated parasitic inductance. These transients laser forward voltage leave insufficient headroom proper operation laser driver modulation output DC-coupled laser diode. solve this problem, MAX3867's modulation output designed AC-coupled cathode laser diode. external pull-up inductor necessary DC-bias modulation output VCC. Such configuration isolates laser forward voltage from output circuitry
allows output OUT+ swing above below supply voltage VCC. simplified functional diagram shown Figure MAX3867 modulation output optimized driving load; minimum required voltage OUT+ 2.0V. Modulation current swings 80mA possible, minimum power supply jitter requirements 2.5Gbps, specified maximum modulation current limited 60mA. interface with laser diode, damping resistor required impedance matching. shunt network also necessary compensate laser-diode parasitic inductance, thereby improving optical output aberrations duty-cycle distortion. data rate 2.5Gbps, capacitive load cathode laser diode will degrade optical output performance. Since BIAS output directly connected laser cathode, minimize parasitic capacitance associated with this using inductor isolate BIAS from laser cathode.
Automatic Power Control
maintain constant average optical power, MAX3867 incorporates loop compensate changes laser threshold current over temperature lifetime. back-facet photodiode mounted
+3.3V, 2.5Gbps SDH/SONET Laser Driver with Automatic Power Control MAX3867
LATCH
MAX3867
OUT+ DATA OUTIMOD
ENABLE IBIAS BIAS
172X
1000pF FAILURE DETECTOR
MODSET RMODSET
BIASMAX FAIL RBIASMAX
CAPC CAPC
APCSET RAPCSET
Figure Functional Diagram
laser package used convert optical power into photocurrent. loop adjusts laser bias current that monitor current matched reference current RAPCSET. time constant loop determined external capacitor (CAPC). eliminate pattern-dependent jitter associated with loop-time constant, guarantee loop stability, recommended value CAPC 0.1µF. When loop functioning, maximum allowable bias current external resistor, RBIASMAX. failure flag (FAIL) when bias current longer adjusted achieve desired aver8
optical power. filter loop noise, external capacitor APCFILT with recommended value 0.1µF. closed-loop operation requires user three currents with external resistors connected between ground BIASMAX, MODSET, APCSET. Detailed guidelines these resistor settings described Design Procedure section.
Open-Loop Operation
necessary, MAX3867 fully operational without APC. this case, laser current directly external resistors connected from ground BIASMAX
+3.3V, 2.5Gbps SDH/SONET Laser Driver with Automatic Power Control
MODSET. Design Procedure section more details open-loop operation.
Programming Bias Current
When using MAX3867 open-loop operation, bias current determined RBIASMAX resistor. select this resistor, determine required bias current +25°C. Refer IBIASMAX RBIASMAX graph Typical Operating Characteristics select value RBIASMAX that corresponds required current +25°C. When using MAX3867 closed-loop operation, RBIASMAX resistor sets maximum bias current available laser diode over temperature life. loop subtract from this maximum value cannot Refer IBIASMAX RBIASMAX graph Typical Operating Characteristics select value RBIASMAX that corresponds end-of-life bias current +85°C.
MAX3867
Optional Data Input Latch
minimize input data pattern-dependent jitter, differential clock signal should connected data input latch, which selected external LATCH control. LATCH high, input data retimed rising edge CLK+. LATCH low, input data directly connected output stage. When this latch function used, connect CLK+ leave CLK- unconnected.
Enable Control
MAX3867 incorporates laser driver enable function. When ENABLE low, both bias modulation currents off. typical laser enable time 250ns typical disable time 25ns.
Slow-Start
laser safety reasons, MAX3867 incorporates slow-start circuit which provides programmable delay time enabling laser diode. external capacitor (CSLWSTRT) connected from this ground programs delay equation: tENABLE 100k (CSLWSTRT 2.5pF)
Programming Loop
When MAX3867's feature used, program average optical power adjusting APCSET resistor. select this resistor, determine desired monitor current maintained over temperature life. Refer RAPCSET graph Typical Operating Characteristics select value RAPCSET that corresponds required current.
Failure Monitor
MAX3867 provides failure monitor (TTL/CMOS) indicate loop tracking failure. FAIL when loop longer adjust bias current maintain desired monitor current.
Interfacing with Laser Diode
minimize optical output aberrations laser parasitic inductance, shunt network required (Figure represents laser diode resistance, recommended total resistance Starting values coaxial lasers 3.3pF. should experimentally adjusted until optical output waveform optimized. bypass capacitor should also placed close laser anode possible, best performance.
Short-Circuit Protection
MAX3867 provides short-circuit protection modulation, bias monitor current sources. either BIASMAX, MODSET, APCSET shorted ground, bias modulation output will turned off.
Pattern-Dependent Jitter (PDJ)
When transmitting data with long strings consecutive identical digits (CID), droop occur contribute pattern-dependent jitter. minimize this
Design Procedure
When designing laser transmitter, optical output usually expressed terms average power extinction ratio. Table gives relationships that helpful converting between optical average power modulation current. These relationships valid average duty cycle optical waveform given laser power PAVE, slope efficiency extinction ration modulation current calculated Table Refer IMOD RMODSET graph Typical Operating Characteristics select value RMODSET that corresponds required current +25°C.
Table Optical Power Definition
PARAMETER Average Power Extinction Ratio Optical Power High Optical Power Optical Amplitude Laser Slope Efficiency Modulation Current SYMBOL PAVE Pp-p IMOD RELATION PAVE 2PAVE 2PAVE Pp-p 2PAVE Pp-p IMOD IMOD Pp-p
Programming Modulation Current
+3.3V, 2.5Gbps SDH/SONET Laser Driver with Automatic Power Control
pattern-dependent jitter, three external components must properly chosen: capacitor CAPC, which dominates loop time constant; pull-up inductor AC-coupling capacitor filter noise effects guarantee loop stability, recommended value CAPC 0.1µF. This results loop bandwidth 10kHz time constant 16µs. result, pattern-dependent jitter associated with loop time constant ignored. time constant associated with output pull-up inductor (LP), AC-coupling capacitor (CD), will also impact pattern-dependent jitter. such second-order network, frequency cutoff will dominated data rate 2.5Gbps, recommended value 0.056µF. During maximum period recommended limit peak voltage droop less than average amplitude). time constant estimated 7.8t /25, 100UI 40ns, then 7.8µH. reduce physical size this element (LP), ferrite beads recommended (Figure
MAX3867
Applications Information
following example MAX3867.
Select Laser
communication-grade laser should selected 2.488Gbps applications. Assume laser output average power PAVE 0dBm, minimum extinction ratio (8.2dB), operating temperature -40°C +85°C, laser diode following characteristics: Wavelength: 1.3µm Threshold Current: 22mA +25°C Threshold Temperature Coefficient: 1.3%/°C Laser Monitor Transfer: 0.2A/W Laser Slope Efficiency: 0.05mW/mA +25°C
Determine RAPCSET desired monitor diode current estimated PAVE 200µA. RAPCSET graph Typical Operating Characteristics shows that RAPCSET should 6.0k. Determine RMODSET achieve minimum extinction ratio (re) 6.6dB over temperature lifetime, calculate required extinction ratio 25°C. Assuming peak-to-peak optical power Pp-p 1.81mW according Table required modulation current 1.81(mW) 0.05(mW/mA) 36.2mA. IMOD RMODSET graph Typical Operating Characteristics shows that RMODSET should 4.8k. Determine RBIASMAX Calculate maximum threshold current (ITH(MAX)) +85°C life. Assuming TH(MAX) 50mA, maximum bias current should
IBIASMAX ITH(MAX) IMOD/2 this example, IBIASMAX 68.1mA. IBIASMAX RBIASMAX graph Typical Operating Characteristics shows that RBIASMAX should 3.2k.
Input Termination Requirement
MAX3867 data clock inputs PECL-compatible. However, necessary drive MAX3867 with standard PECL signal. long specified common-mode voltage differential voltage swings met, MAX3867 will operate properly.
Calculate Power Consumption
junction temperature MAX3867 dice must kept below +150°C times. total power dissipation MAX3867 estimated following: (VCC IBIAS IMOD (VCC IMOD where IBIAS maximum bias current RBIASMAX, IMOD modulation current, typical laser forward voltage. Junction temperature P(W) (°C/W)
+3.3V, 2.5Gbps SDH/SONET Laser Driver with Automatic Power Control
Modulation Current More than 60mA
power supply, headroom voltage MAX3867 significantly improved. this case, possible achieve modulation current more than 60mA with AC-coupling, junction temperature kept below 150°C. MAX3867 also DC-coupled laser diode when operating supply; voltage OUT+ should 2.0V proper operation.
Laser Safety
Using MAX3867 laser driver alone does ensure that transmitter design compliant with 825. entire transmitter circuit component selections must considered. Each customer must determine level fault tolerance required their application, recognizing that Maxim products designed authorized components systems intended surgical implant into body, applications intended support sustain life, other application where failure Maxim product could create situation where personal injury death occur.
MAX3867
Wire Bonding
high current density reliable operation, MAX3867 uses gold metalization. Make connections with gold wire only, using ball-bonding techniques. Wedge bonding recommended. Die-pad size mils (100µm) square, thickness mils (300µm) mils.
Layout Considerations
minimize inductance, keep connections between MAX3867 output pins close possible. Optimize laser diode performance placing bypass capacitor close possible laser anode. good high-frequency layout techniques multilayer boards with uninterrupted ground planes minimize crosstalk.
Configuration
BIASMAX MODSET APCSET
Chip Topography
CLK- VCC1 VCC1 DATA+ GND1 VCC1 CLK+ GND1 DATA- VCC1 GND1 LATCH GND2 VCC2 BIASMAX MODSET GND2 APCSET 0.083" N.C. (2.108mm) GND2 N.C. GND3 N.C. CAPC VCC3 GND3
VIEW
VCC2
GND2
GND2
GND3
CAPC
GND2 GND1 VCC1 DATA+ DATAVCC1 GND1 VCC1 CLK+
VCC3
GND3 GND3 GND4
N.C.
N.C.
N.C.
ENABLE GND1 GND1 SLWSTRT VCC1 FAIL GND4 N.C. APCFILT GND4 VCC4 BIAS
MAX3867
VCC4 N.C. OUT29 OUT+ N.C. VCC4 N.C. BIAS
CLK- VCC1 GND1
SLWSTRT
APCFILT
LATCH
ENABLE
GND1
FAIL
GND4
GND4
VCC1
N.C.
GND1
VCC4
N.C. N.C. OUT- VCCA GND3 VCC4 OUT+ N.C. GND4 0.070" (1.778mm)
TQFP
+3.3V, 2.5Gbps SDH/SONET Laser Driver with Automatic Power Control MAX3867
Package Information
TQFPPO.EPS
Maxim makes warranty, representation guarantee regarding suitability products particular purpose, does Maxim assume liability arising application product circuit specifically disclaims liability, including without limitation consequential incidental damages. "Typical" parameters vary different applications. operating parameters, including "typicals" must validated each customer application customer's technical experts. Maxim products designed, intended authorized components systems intended surgical implant into body, other applications intended support sustain life, other application which failure Maxim product could create situation where personal injury death occur.
_Maxim Integrated Products, Gabriel Drive, Sunnyvale, 94086 408-737-7600 1998 Maxim Integrated Products Printed registered trademark Maxim Integrated Products.

+3.3V, 2.5Gbps SDH/SONET Laser Driver with Automatic Power Control

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