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general description the max3869 is a complete, single +3.3v laser driverfor sdh/sonet applications up to 2.5gbps. the device accepts differential pecl data and clock inputs and provides bias and modulation currents for driving a laser. a synchronizing input latch can be used (if a clock signal is available) to reduce jitter. an automatic power control (apc) feedback loop is incorporated to maintain a constant average optical power over temperature and lifetime. the wide modula- tion current range of 5ma to 60ma and bias current of 1ma to 100ma are easy to program, making this prod- uct ideal for use in various sdh/sonet applications. the max3869 also provides enable control, two current monitors that are directly proportional to the laser bias and modulation currents, and a failure-monitor output to indi- cate when the apc loop is unable to maintain the average optical power. the max3869 is available in 32-pin tqfp and small 32-pin qfn packages as well as dice. applications sonet/sdh transmission systemsadd/drop multiplexers digital cross-connects section regenerators 2.5gbps optical transmitters features ? single +3.3v or +5v power supply ? 64ma supply current at +3.3v ? programmable bias current from 1ma to 100ma ? programmable modulation current from 5ma to 60ma ? bias current and modulation current monitors ? 87ps rise/fall time ? automatic average power control with failuremonitor ? complies with ansi, itu, and bellcoresdh/sonet specifications ? enable control * exposed pad. ** package code: g3255-1 *** dice are designed to operate over this range, but are tested and guaranteed at t a = +25? only. contact factory for availability. + denotes lead-free package. ordering information max3869 +3.3v, 2.5gbps sdh/sonet laser driver with current monitors and apc ________________________________________________________________ maxim integrated products 1 evaluation kit available 124 ? 124 ? serializer with clock gen. 124 ? 23 ? ld 25 ? +3.3v +3.3v 0.056 f 0.01 f biasmon modmon +3.3v 1000pf biasmax latchenable fail modsetapcset apcfilt clk- clk+ data- data+ ferritebead out+ bias md out- capc 124 ? 84.5 ? 84.5 ? 84.5 ? 84.5 ? max3869 max3890 typical application circuit 19-1570; rev 4; 1/05 pin configuration appears at end of data sheet. for pricing, delivery, and ordering information, please contact maxim/dallas direct! at 1-888-629-4642, or visit maxim? website at www.maxim-ic.com. part temp range pin-package MAX3869EHJ -40? to +85? 32 tqfp-ep* MAX3869EHJ+ -40? to +85? 32 tqfp-ep* max3869egj -40? to +85? 32 qfn** max3869e/d -40? to +85? dice*** downloaded from: http:///
max3869 +3.3v, 2.5gbps sdh/sonet laser driver with current monitors and apc 2 _______________________________________________________________________________________ i md = 1ma i md = 18? 90 enable = low (note 4) apc open loop (note 3) 900 (note 2) (note 5) sourcing 50? enable, latch (note 6) enable, latch i bias = 100ma apc open loop figure 1 pecl compatible sinking 100? conditions % -15 15 monitor-diode bias absoluteaccuracy ppm/? -480 50 480 monitor-diode bias setpointstability ? 18 1000 i md monitor-diode dc current range v 1.5 monitor-diode reverse biasvoltage v 0.1 0.44 ttl output low voltage fail ? 100 i bias-off bias off-current ma 1 100 i bias ma 64 112 i cc supply current bias current range v 2.4 v cc - 0.3 v cc ttl output high voltage fail v 0.8 ttl input low voltage v 2.0 ttl input high voltage ? -1 10 i in clock and data input current ppm/? 230 bias-current stability % -15 15 (note 5) bias-current absolute accuracy mvp-p 200 1600 v id differential input voltage v v cc - v cc - v cc - 1.49 1.32 v id /4 v icm common-mode input voltage units min typ max symbol parameter dc electrical characteristics (v cc = +3.14v to +5.5v, t a = -40? to +85?. typical values are at v cc = +3.3v, i mod = 30ma, i bias = 60ma, t a = +25?, unless otherwise noted.) (note 1) stresses beyond those listed under ?bsolute 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, v cc ............................................. -0.5v to +7.0v current into bias ...........................................-20ma to +150ma current into out+, out- ................................-20ma to +100ma current into md.....................................................-5ma to +5ma voltage at data+, data-, clk+, clk-, enable, latch, fail , biasmon, modmon .....-0.5v to (v cc + 0.5v) voltage at apcfilt, capc, modset, biasmax, apcset ...........................................-0.5v to +3.0v voltage at out+, out-.............................+1.5v to (v cc + 1.5v) voltage at bias .........................................+1.0v to (v cc + 0.5v) continuous power dissipation (t a = +85?) 32-pin tqfp-ep (derate 22.2mw/? above +85?) ..1444mw 32-pin qfn (derate 20.84mw/? above +85?) .......1667mw storage temperature range .............................-65? to +165? operating junction temperature range ...........-55? to +150? processing temperature (die) .........................................+400? lead temperature (soldering, 10s) .................................+300? absolute maximum ratings i bias /i biasmon a/a 37 a bias biasmon to i bias gain i mod /i modmon a/a 29 a mod modmon to i mod gain i bias = 1ma downloaded from: http:///
max3869 +3.3v, 2.5gbps sdh/sonet laser driver with current monitors and apc _______________________________________________________________________________________ 3 ac electrical characteristics (v cc = +3.14v to +5.5v, load as shown in figure 2, t a = -40? to +85?. typical values are at v cc = +3.3v, i mod = 30ma, t a = +25?.) (note 7)note 1: dice are tested at t a = +25? only. note 2: tested at r modset = 2.49k ? , r biasmax = 1.69k ? , excluding i bias and i mod . note 3: voltage on bias pin is (v cc - 1.6v). note 4: both the bias and modulation currents will be switched off if any of the current set pins are grounded. note 5: accuracy refers to part-to-part variation. note 6: assuming that the laser to monitor-diode transfer function does not change with temperature. guaranteed by design and characterization. note 7: ac characteristics are guaranteed by design and characterization. note 8: measured with 622mbps 0-1 pattern, latch = high. note 9: pwd = (wider pulse - narrower pulse) / 2. note 10: see typical operating characteristics for worst-case distribution. i mod = 5ma 300 78 latch = high, figure 3 latch = high, figure 3 20% to 80% (note 8) ps 69 (note 8) 20% to 80% (note 8) enable = low (note 4) i mod = 60ma (note 5) jitter bw = 12khz to 20mhz, 0-1 pattern (notes 8, 9) conditions t r output rise-time ps ps p-p 72 0 jitter generation ps 14 50 pwd pulse-width distortion ma 56 0 i mod modulation-current range ps 100 t h ps 100 t su input latch setup time input latch hold time bits 80 maximum consecutive identicaldigits ns 250 enable and start-up delay % ?5 output aberrations 79 t f output fall- time ? 200 i mod-off modulation-off current ppm/? -480 -8 480 modulation-current stability % -15 15 modulation-current absoluteaccuracy 87 (note 10) units min typ max symbol parameter MAX3869EHJ max3869e/d MAX3869EHJ max3869e/d data+ data- (data+) - (data-) i out + 100mv min800mv max 200mvp-p min1600mvp-p max i mod figure 1. required input signal and output polarity downloaded from: http:///
max3869 +3.3v, 2.5gbps sdh/sonet laser driver with current monitors and apc 4 _______________________________________________________________________________________ clk data t clk = 402ps t su t h figure 3. setup/hold time definition 0.056 f out+ bias out- ab a a, b are smd ferrite beads:b = blm11a601s murata electronics a = blm21a102s murata electronics b v cc 50 ? 15 ? oscilloscope 50 ? 25 ? 0.056 f v cc max3869 i out + figure 2. output termination for characterization typical operating characteristics (v cc = +3.3v, load as shown in figure 2, t a = +25?, unless otherwise noted.) eye diagram (2.488gbps, 1300nm fp laser, 1.87ghz filter, 32 tqfp-ep) max3869-01 48ps/div mitsubishi ml725c8f laser diode 0 5 1510 20 25 84 83 87 32 tqfp-epi mod = 30ma mean = 87.3ps = 1.6ps 88 90 89 86 85 91 92 typical distribution of fall time max3869-02 fall time (ps) percent of units (%) 0 5 2015 10 3025 35 114.5 113 119 32 tqfp-epi mod = 60ma v cc = 3.14v t a = +85? mean = 119.1ps = 2.0ps 120.5 123.5 122 117.5 116 125 126.5 distribution of fall time (worst-case conditions) max3869-03 fall time (ps) percent of units (%) downloaded from: http:///
max3869 +3.3v, 2.5gbps sdh/sonet laser driver with current monitors and apc _______________________________________________________________________________________ 5 120 0 11 0 100 300 i biasmax vs. r biasmax max3869-07 r bia s max ( k ? ) i biasmax (ma) 40 80 100 20 60 1.2 0 0.1 1 10 100 i md vs. r apcset 0.4 max3869-09 r ap cs et ( k ? ) i md (ma) 0.6 0.8 1.0 1.10.3 0.2 0.1 0.5 0.7 0.9 100 0 1 10 100 i mod vs. r modset 2010 max3869-08 r m o d s et ( k ? ) i mod (ma) 4030 60 7050 80 90 0 10 6050 40 30 20 90 70 80 100 -40 -15 10 35 60 85 supply current vs. temperature (exclude i bias , i mod , 25 ? load) max3869-10 temperature ( c) supply current (ma) v cc = +5.5v v cc = +3.14v 0 10 3020 40 50 -40 -15 10 35 60 85 bias-current monitor gain vs. temperature max3869-11 temperature (?) gain (i bias /i biasmon ) i bias = 100ma, i mod = 50ma i bias = 10ma, i mod = 10ma electrical eye diagram (i mod = 30ma, 2 13 -1 +80 cid, 32 tqfp-ep) max3869-04 100ps/div 250mv/div electrical eye diagram (i mod = 60ma, 2 13 -1 +80 cid, 32 tqfp-ep) max3869-05 100ps/div 400mv/div 3.0 4.03.5 5.04.5 6.05.5 6.5 7.57.0 8.0 5 152025 10 30 35 40 45 50 random jitter vs. i mod max3869-06 i mod (ma) random jitter (psp-p) typical operating characteristics (continued) (v cc = +3.3v, load as shown in figure 2, t a = +25?, unless otherwise noted.) downloaded from: http:///
max3869 +3.3v, 2.5gbps sdh/sonet laser driver with current monitors and apc 6 _______________________________________________________________________________________ pin description typical operating characteristics (continued) (v cc = +3.3v, load as shown in figure 2, t a = +25?, unless otherwise noted.) name function 1, 4, 7 v cc 1 power supply for digital circuits 2 data+ noninverting pecl input pin 3 data- inverting pecl input 8 latch ttl/cmos latch input. high for latched data, low for direct data. internal 100k ? pull-up to v cc . 6 clk- negative pecl clock input. leave unconnected if latch function is not used. 5 clk+ positive pecl clock input. connect to v cc if latch function is not used. 14 apcfilt connect a capacitor (c apcfilt = 0.1?) from this pad to ground to filter the apc noise. 12 modmon modulation current monitor. sink current source that is proportional to the laser modulationcurrent. 11 biasmon bias current monitor. sink current source that is proportional to the laser bias current. 10, 15 gnd1 ground for digital circuits 9 enable ttl/cmos enable input. high for normal operation, low to disable laser bias and modulationcurrent. internal 100k ? pull-up to v cc . 19 out+ positive modulation-current output. i mod flows through this pad when input data is high. 16, 18, 21 v cc4 power supply for output circuitry 17 bias laser bias current output 13 fail ttl/cmos failure output. indicates apc failure when low. 0. 5 1510 20 25 52 0 10 30 40 50 60 pulse-width distortion vs. i mod max3869-13 i mod (ma) pwd (ps) v cc = +5v v cc = +3.3v 0 5 10 15 20 25 30 35 40 -40 -15 10 35 60 85 modulation-current monitor gain vs. temperature max3869-12 temperature (?) gain (i mod /i modmon ) i bias = 100ma, i mod = 50ma i bias = 10ma, i mod = 10ma downloaded from: http:///
_______________detailed description the max3869 laser driver consists of two main parts: ahigh-speed modulation driver and a laser-biasing block with automatic power control (apc). the circuit design is optimized for both high-speed and low-voltage (+3.3v) operation. to minimize the pattern-dependent jitter of the input signal at speeds as high as 2.5gbps, the device accepts a differential pecl clock signal for data retiming. when latch is high, the input data is synchronized by the clock signal. when latch is low, the input data is directly applied to the output stage. the output stage is composed of a high-speed differential pair and a programmable modulation current source. since the modulation output drives a maximum current of 60ma into the laser with an edge speed of 100ps, large transient voltage spikes can be generated (due to the parasitic inductance). these transients and the laser forward voltage leave insufficient headroom for the proper operation of the laser driver if the modulation output is dc-coupled to the laser diode. to solve this problem, the max3869? modulation output is designed to be ac-coupled to the cathode of a laser diode. an external pull-up inductor is necessary to dc-bias the modulation output at v cc . such a configuration isolates laser forward voltage from the output circuitry and allows the output at out+ to swing above and belowthe supply voltage v cc . a simplified functional diagram is shown in figure 4.the max3869 modulation output is optimized for driv- ing a 25 ? load; the minimum required voltage at out+ is 2.0v. modulation current swings of 80ma are possi-ble, but due to minimum power-supply and jitter requirements at 2.5gbps, the specified maximum mod- ulation current is limited to 60ma. to interface with the laser diode, a damping resistor (r d ) is required for impedance matching. an rc shunt network may alsobe necessary to compensate for the laser-diode para- sitic inductance, thereby improving the optical output aberrations and duty-cycle distortion. at the data rate of 2.5gbps, any capacitive load at the cathode of a laser diode will degrade the optical output performance. since the bias output is directly connect- ed to the laser cathode, minimize the parasitic capaci- tance associated with this pin by using an inductor to isolate the bias pin from the laser cathode. automatic power control to maintain constant average optical power, themax3869 incorporates an apc loop to compensate for the changes in laser threshold current over temperature and lifetime. a back-facet photodiode mounted in the max3869 +3.3v, 2.5gbps sdh/sonet laser driver with current monitors and apc _______________________________________________________________________________________ 7 name function pin 25 v cc3 power supply for apc 24 md monitor diode input. connect this pad to a monitor photodiode anode. a capacitor to groundis required to filter high-speed ac monitor photocurrent. 20 out- negative modulation-current output. i mod flows through this pad when input data is low. 32 v cc2 power supply for internal reference 31 biasmax a resistor connected from this pad to ground sets the maximum bias current. the apc function can subtract from this maximum value, but cannot add to it. 30 modset a resistor connected from this pad to ground sets the desired modulation current. 29 apcset a resistor connected from this pad to ground sets the desired average optical power.connect 100k ? from this pad to ground if apc is not used. 26 capc a capacitor connected from this pad to ground controls the dominant pole of the apc feed-back loop (c apc = 0.1?). pin description (continued) 22 gnd4 ground for output circuitry 23 gnd3 ground for apc 27 gnd2 ground for internal reference 28 n.c. no connection. leave unconnected. downloaded from: http:///
max3869 laser package is used to convert the optical power intoa photocurrent. the apc loop adjusts the laser bias current so that the monitor current is matched to a ref- erence current set by r apcset . the time constant of the apc loop is determined by an external capacitor(c apc ). to eliminate the pattern-dependent jitter asso- ciated with the apc loop-time constant, and to guaran-tee loop stability, the recommended value for c apc is 0.1?.when the apc loop is functioning, the maximum allow- able bias current is set by an external resistor, r biasmax . an apc failure flag ( fail ) is set low when the bias current can no longer be adjusted to achieve the desired aver-age optical power. to filter out the apc loop noise, use an external capacitor at apcfilt with a recommendedvalue of 0.1?. apc closed-loop operation requires the user to set three currents with external resistors connected between ground and biasmax, modset, and apcset. detailed guidelines for these resistor settings are described in the design procedure section. open-loop operation if necessary, the max3869 is fully operational withoutapc. in this case, the laser current is directly set by two external resistors connected from ground to biasmax and modset. see the design procedure section for more details on open-loop operation. +3.3v, 2.5gbps sdh/sonet laser driver with current monitors and apc 8 _______________________________________________________________________________________ latch c d v cc 1000pf i md r apcset r biasmax r modset apcset capc c apc biasmax md modset fail bias r d 25 ? i mod i bias l p1 v cc data clk enable biasmon mobmon out+ out- dq 165x failure detector 40x 5x 29 max3869 r p l p2 i mod 37 i bias 0 mux 1 figure 4. functional diagram downloaded from: http:///
optional data input latch to minimize input data pattern-dependent jitter, the dif-ferential clock signal should be connected to the data input latch, which is selected by an external latch control. if latch is high, the input data is retimed by the rising edge of clk+. if latch is low, the input data is directly connected to the output stage. when this latch function is not used, connect clk+ to v cc and leave clk- unconnected. enable control the max3869 incorporates a laser driver enable func-tion. when enable is low, both the bias and modulation currents are off. the typical laser enable time is 250ns, and the typical disable time is 25ns. current monitors the max3869 features bias- and modulation-currentmonitor outputs. the biasmon output sinks a current equal to 1/37 of the laser bias current (i bias / 37). the modmon output sinks a current equal to 1/29 of thelaser modulation current (i mod / 29). biasmon and modmon should be connected through a pull-up resis-tor to v cc . choose a pull-up resistor value that ensures a voltage at biasmon greater than v cc - 1.6v and a volt- age at modmon greater than v cc - 1.0v. slow-start for laser safety reasons, the max3869 incorporates aslow-start circuit that provides a delay of 250ns for enabling a laser diode. apc failure monitor the max3869 provides an apc failure monitor(ttl/cmos) to indicate an apc loop tracking failure. fail is set low when the apc loop can no longer adjust the bias current to maintain the desired monitor current. short-circuit protection the max3869 provides short-circuit protection for themodulation, bias, and monitor current sources. if either biasmax, modset, or apcset is shorted to ground, the bias and modulation output will be turned off. design procedure when designing a laser transmitter, the optical output isusually expressed in terms of average power and extinc- tion ratio. table 1 gives the relationships that are helpfulin converting between the optical average power and the modulation current. these relationships are valid if the mark density and duty cycle of the optical waveform are 50%. programming the modulation current for a given laser power p avg , slope efficiency ( ) , and extinction ration (r e) , the modulation current can be cal- culated using table 1. see the i mod vs. r modset graph in the typical operating characteristics and select the value of r modset that corresponds to the required cur- rent at +25?. programming the bias current when using the max3869 in open-loop operation, thebias current is determined by the r biasmax resistor. to select this resistor, determine the required bias currentat +25?. see the i biasmax vs. r biasmax graph in the typical operating characteristics and select the value of r biasmax that corresponds to the required current at +25?.when using the max3869 in closed-loop operation, the r biasmax resistor sets the maximum bias current avail- able to the laser diode over temperature and life. theapc loop can subtract from this maximum value but cannot add to it. see the i biasmax vs. r biasmax graph in the typical operating characteristics and select the value of r biasmax that corresponds to the end-of-life bias current at +85?. programming the apc loop when the max3869? apc feature is used, program theaverage optical power by adjusting the apcset resistor. to select this resistor, determine the desired monitor cur- rent to be maintained over temperature and life. see the i md vs. r apcset graph in the typical operating characteristics and select the value of r apcset that cor- responds to the required current. interfacing with laser diodes to minimize optical output aberrations caused by signalreflections at the electrical interface to the laser diode, a series damping resistor (r d ) is required (figure 4). additionally, the max3869 outputs are optimized for a25 ? load. therefore, the series combination of r d and r l (where r l represents the laser-diode resistance) max3869 +3.3v, 2.5gbps sdh/sonet laser driver with current monitors and apc _______________________________________________________________________________________ 9 parameter symbol relation average power p avg p avg = (p 0 + p 1 ) / 2 extinction ratio r e r e = p 1 / p 0 optical power high p 1 p 1 = 2p avg r e / (r e + 1) optical power low p 0 p 0 = 2p avg / (r e + 1) optical amplitude pp-p pp-p = 2p avg (r e - 1) / (r e + 1) laser slopeefficiency = pp-p / i mod modulation current i mod i mod = pp-p / table 1. optical power definition downloaded from: http:///
max3869 should equal 25 ? . typical values for r d are 18 ? to 23 ? . for best performance, a bypass capacitor (0.01? typical) should be placed as close as possible to theanode of the laser diode. depending on the exact char- acteristics of the laser diode and pc board layout, a resistor (r p ) of 20 ? to 70 ? in parallel with pull-up induc- tor l p1 can be useful in damping overshoot and ringing in the optical output. in some applications (depending on laser-diode para- sitic inductance characteristics), an rc shunt network between the laser cathode and ground will help mini- mize optical output aberrations. starting values for most coaxial lasers are r = 75 ? in series with c = 3.3pf. these values should be experimentally adjusted untilthe optical output waveform is optimized. pattern-dependent jitter when transmitting nrz data with long strings of con-secutive identical digits (cids), lf droop can occur and contribute to pattern-dependent jitter (pdj). to minimize this pdj, three external components must be properly chosen: capacitor c apc , which dominates the apc loop time constant; pull-up inductor l p ; and ac- coupling capacitor c d . to filter out noise effects and guarantee loop stability,the recommended value for c apc is 0.1?. this results in an apc loop bandwidth of 10khz or a time constantof 16?. as a result, the pdj associated with an apc loop time constant can be ignored. the time constant associated with the output pull-up inductor (l p l p2 ), and the ac-coupling capacitor (c d ) will also impact the pdj. for such a second-order net-work, the pdj due to the low frequency cutoff will be dominated by l p . for a data rate of 2.5gbps, the rec- ommended value for c d is 0.056?. during the maxi- mum cid period , it is recommended to limit the peak voltage droop to less than 12% of the average (6% ofthe amplitude). the time constant can be estimated by: 12% = 1 - e -t / l p lp = 7.8t if lp = l p / 25 ? , and t = 100ui = 40ns, then l p = 7.8?. to reduce the physical size of this element (l p ), use of smd ferrite beads is recommended (figure 2). input termination requirement the max3869 data and clock inputs are pecl compat-ible. however, it is not necessary to drive the max3869 with a standard pecl signal. as long as the specified common-mode voltage and the differential voltage swings are met, the max3869 will operate properly. calculating power consumption the junction temperature of the max3869 dice must bekept below +150? at all times. the total power dissipa- tion of the max3869 can be estimated by the following: p = v cc ? i cc + (v cc - v f ) ? i bias + i mod (v cc - 25 ? ? i mod / 2) where i bias is the maximum bias current set by r bias- max , i mod is the modulation current, and v f is the typi- cal laser forward voltage. junction temperature = p(w) ? 45 (?/w) ___________applications information an example of how to set up the max3869 follows. select laser a communication-grade laser should be selected for2.488gbps applications. assume the laser output aver- age power is p avg = 0dbm, minimum extinction ratio is r e = 6.6 (8.2db), the operating temperature is -40? to +85?, and the laser diode has the following character-istics: wavelength: = 1.3? threshold current: th = 22ma at +25? threshold temperaturecoefficient: th = 1.3%/? laser to monitor transfer: mon = 0.2a/w laser slope efficiency: = 0.05mw/ma at +25? determine r apcset the desired monitor diode current is estimated by i md = p avg mon = 200?. the i md vs. r apcset graph in the typical operating characteristics shows that r apcset should be 6.0k ? . determine r modset to achieve a minimum extinction ratio (r e ) of 6.6 over temperature and lifetime, calculate the required extinc-tion ratio at +25?. assuming r e = 20, the peak-to-peak optical power p p-p = 1.81mw, according to table 1. the required modulation current is 1.81(mw) / 0.05(mw/ma)= 36.2ma. the i mod vs. r modset graph in the typical operating characteristics shows that r modset should be 4.8k ? . +3.3v, 2.5gbps sdh/sonet laser driver with current monitors and apc 10 ______________________________________________________________________________________ downloaded from: http:///
determine r biasmax calculate the maximum threshold current (i th(max) ) at t a = +85? and end of life. assuming i th(max) = 50ma, the maximum bias current should be: i biasmax = i th(max) + i mod /2 in this example, i biasmax = 68.1ma. the i biasmax vs. r biasmax graph in the typical operating characteristics shows that r biasmax should be 3.2k ? . modulation currents exceeding 60ma with a +5v power supply, the headroom voltage for themax3869 is significantly improved. in this case, it is possible to achieve a modulation current of more than 60ma with ac-coupling, if the junction temperature is kept below 150?. the max3869 can also be dc-cou- pled to a laser diode when operating with a +5v sup- ply; the voltage at out+ should be 2.0v for proper operation. wire bonding die for high current density and reliable operation, themax3869 uses gold metalization. make connections to the die with gold wire only, using ball-bonding tech- niques. wedge bonding is not recommended. die-pad size is 4 mils (100?) square, and die thickness is 12 mils (300?) square. layout considerations to minimize inductance, keep the connections betweenthe max3869 output pins and ld as close as possible. optimize the laser diode performance by placing a bypass capacitor as close as possible to the laser anode. use good high-frequency layout techniques and multilayer boards with uninterrupted ground planes to minimize emi and crosstalk. laser safety and iec 825 using the max3869 laser driver alone does not ensurethat a transmitter design is compliant with iec 825. the entire transmitter circuit and component selections must be considered. each customer must determine the level of fault tolerance required by their application, recogniz- ing that maxim products are not designed or authorized for use as components in systems intended for surgical implant into the body, for applications intended to sup- port or sustain life, or for any other application where the failure of a maxim product could create a situation where personal injury or death may occur. max3869 +3.3v, 2.5gbps sdh/sonet laser driver with current monitors and apc ______________________________________________________________________________________ 11 chip information transistor count: 1561substrate connected to gnd downloaded from: http:///
max3869 +3.3v, 2.5gbps sdh/sonet laser driver with current monitors and apc 12 ______________________________________________________________________________________ pin configurations chip topography max3869 top view 32 28 29 30 31 25 26 27 biasmaxmodset apcset n.c. v cc2 gnd2capc v cc3 10 13 15 14 16 11 12 9 enable biasmon gnd1 fail modmon gnd1 apcfilt v cc4 17 18 19 20 21 22 23 gnd3 24 mdgnd4 v cc4 out-out+ v cc4 bias 2 3 4 5 6 7 8 latch v cc1 clk- clk+ v cc1 data- data+ 1 v cc1 tqfp-ep* *exposed pad is connected to gnd. latch gnd1 v cc1 clk+ gnd1 data- v cc1 clk- v cc1 v cc1 data+ gnd1 enable gnd1 gnd1 biasmon modmon fail gnd4 n.c. apcfilt gnd4 v cc4 md gnd4 n.c. out+ v cc4 out- n.c. n.c. gnd3 v cc4 bias v cc2 gnd2biasmax modset gnd2 apcset n.c. gnd3 n.c. gnd3 n.c. capc v cc3 gnd3 0.083" (2.108mm) 0.070" (1.778mm) max3869 top view 32 28 29 30 31 25 26 27 biasmaxmodset apcset n.c. v cc2 gnd2capc v cc3 10 13 15 14 16 11 12 9 enable biasmon gnd1 fail modmon gnd1 apcfilt v cc4 17 18 19 20 21 22 23 gnd3 24 mdgnd4 v cc4 out-out+ v cc4 bias 2 3 4 5 6 7 8 latch v cc1 clk- clk+ v cc1 data- data+ 1 v cc1 qfn* *exposed pad is connected to gnd. downloaded from: http:///
max3869 +3.3v, 2.5gbps sdh/sonet laser driver with current monitors and apc ______________________________________________________________________________________ 13 32l,tqfp.eps f 1 2 21-0079 package outline,32l tqfp, 5x5x1.0mm, ep option package information (the package drawing(s) in this data sheet may not reflect the most current specifications. for the latest package outline information, go to www.maxim-ic.com/packages .) downloaded from: http:///
f 2 2 21-0079 package outline,32l tqfp, 5x5x1.0mm, ep option package information (continued) (the package drawing(s) in this data sheet may not reflect the most current specifications. for the latest package outline information, go to www.maxim-ic.com/packages .) max3869 +3.3v, 2.5gbps sdh/sonet laser driver with current monitors and apc 14 ______________________________________________________________________________________ downloaded from: http:///
maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim product. no circuit patent licenses are implied. maxim reserves the right to change the circuitry and specifications without notice at any time. maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 ____________________ 15 2005 maxim integrated products printed usa is a registered trademark of maxim integrated products, inc. max3869 +3.3v, 2.5gbps sdh/sonet laser driver with current monitors and apc 32l qfn.eps package information (continued) (the package drawing(s) in this data sheet may not reflect the most current specifications. for the latest package outline information, go to www.maxim-ic.com/packages .) downloaded from: http:///

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