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general description the max3800 is a +3.3v adaptive cable equalizer andcable driver implemented together on a single chip. it is designed for coaxial and twin-axial cable point-to-point communications applications. the driver features differ- ential current-mode logic (cml) inputs and outputs as well as adjustable output amplitude. the equalizer includes differential cml data inputs and outputs, a loss-of-signal ( los ) output, and a cable integrity moni- tor (cim) output. the adaptive cable equalizer is capable of equalizing differential or single-ended signals at data rates up to 3.2gbps. it automatically adjusts to attenuation caused by skin-effect losses of up to 30db at 1.6ghz. the equalizer effectively extends the usable length of cop- per cable in high-frequency interconnect applications. the max3800 is available in a 32-pin tqfp package with exposed pad and consumes only 200mw at +3.3v. the driver can be disconnected from the power supply when it is not needed, resulting in a 40% reduc- tion in supply current. applications high-speed links in communicationsand data systems backplane and interconnect applications sdh/sonet transmission equipment features ? single +3.3v operation ? typical power dissipation = 200mw at +3.3v ? data rates up to 3.2gbps ? adjustable cable driver output amplitude ? equalizer automatically adjusts for differentcable lengths ? 0db to 30db equalization at 1.6ghz (3.2gbps) ? loss-of-signal ( los ) indicator ? cable integrity monitor (cim) ? on-chip input and output terminations ? low external component count ? operating temperature range = 0 c to +85 c ? esd protection on cable inputs and outputs max3800 3.2gbps adaptive equalizer and cable driver ________________________________________________________________ maxim integrated products 1 ordering information dout ein din e out max3800 dout ein din this symbol indicates a controlled-impedance transmission line. e out rmod cim max3800 card 2 card 1 +3.3v +3.3v los rmod cim los t ypical application circuit 19-1953; rev 3; 12/05 part temp range pin-package pkg code max3800ugj 0 c to +85 c 32 qfn g3255-1 max3800uhj 0 c to +85 c 32 tqfp-ep* aa-ep max3800uhj+ 0 c to +85 c 32 tqfp-ep* aa-ep * ep = exposed pad + denotes lead-free package. 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. downloaded from: http:///
max3800 3.2gbps adaptive equalizer and cable driver 2 _______________________________________________________________________________________ absolute maximum ratings dc electrical characteristics(v cc = +3.14v to +3.46v, t a = 0? to +85?. typical values are at v cc = +3.3v and t a = +25?, unless otherwise noted.) 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 +6.0v voltage at los , rmod, and cim...............-0.5v to (v cc + 0.5v) voltage at ein+, ein-, din+, din- .....(v cc - 1v) to (v cc + 0.5v) current out of eout+, eout-, dout+, dout- ................25ma continuous power dissipation (t a = +85?) 32-pin tqfp-ep (derate 22.2mw/? above +85?) ...1444mw operating ambient temperature range ................0? to +85? storage temperature range .............................-55? to +150? lead temperature (soldering, 10s) .................................+300? parameter symbol conditions min typ max units supply current i cc includes external load current (note 1) 65 85 ma cable driver input specifications input voltage (single-ended) v din+, v din- v cc - 0.6 v cc + 0.2 v input voltage (differential) v din v din = (v din+ ) - (v din- ) 400 1100 mvp-p input impedance single-ended 45 55 65 cable driver output specifications r mod = 10k (note 2) 750 870 1000 mvp-p output voltage(differential) r mod = 20k (note 2) 400 450 550 mvp-p output impedance single-ended 50 62.5 75 cable equalizer input specifications m i ni m um c ab l e inp ut ( d i ffer enti al ) 3.2gbps, 30db cable loss at 1.6ghz (note 3) 650 700 mvp-p m axi m um c ab l e inp ut ( d i ffer enti al ) 1100 mvp-p input impedance single-ended 45 55 65 cable equalizer output specifications output voltage (differential) (note 2) 500 1000 mvp-p output impedance single-ended 50 62.5 75 v ol tag e at c im outp ut ( d i ffer enti al ) v cim no external load, v cim = (v cim+ ) - (v cim- ) -0.5 +0.5 vp-p voltage at cim output(single-ended) v cim+, v cim- no external load 0.5 v cc - 0.5 v output high (note 4) 2.4 v voltage at los output low (note 4) 0.4 v outp ut c om m on- m od e v ol tag e each output dc-coupled 50 to v cc v cc - 0.2 v downloaded from: http:///
max3800 3.2gbps adaptive equalizer and cable driver _______________________________________________________________________________________ 3 note 1: equalizer and driver total currents (equalizer with maximum equalization and driver with maximum output swing). note 2: input voltage within specification limits, 50 to v cc at each output. note 3: minimum cable input for los to assert high. note 4: 100k load to ground. note 5: ac electrical characteristics are guaranteed by design and characterization. note 6: v din = 400mvp-p to 1100mvp-p (differential), 10k ? rmod 20k , 3.2gbps 2 13 -1 prbs with 100 consecutive ones and 100 consecutive zeros substituted. note 7: includes random jitter and deterministic jitter. note 8: differential cable input voltage = 700mvp-p, 3.2gbps 2 13 -1 prbs with 100 consecutive ones and 100 consecutive zeros substituted. cable loss is due to skin effect only. ac electrical characteristics(v cc = +3.14v to +3.46v, t a = 0? to +85?. typical values are at v cc = +3.3v and t a = +25?, unless otherwise noted.) (note 5) parameter symbol conditions min typ max units maximum input data rate 3.2 gbps cable driver specifications random jitter (note 6) 2 4 mui rms deterministic jitter (note 6) 20 60 muip-p output edge speed 20% to 80% 59 76 ps input return loss (single-ended) 3.2ghz 14 db outp ut retur n lo ss ( s i ng l e- e nd ed ) 3.2ghz 14 db equalizer specifications 0db cable loss (note 8) 170 240 muip-p 24db cable loss (note 8) 97 200 muip-p residual jitter (note 7) 30db cable loss (note 8) 112 200 muip-p output edge speed 20% to 80% 56 77 ps input return loss (single-ended) 3.2ghz 14 db outp ut retur n lo ss ( s i ng l e- e nd ed ) 3.2ghz 14 db equalization compensation 1.6ghz (skin-effect losses only) 30 db equalization time constant 5 s downloaded from: http:///
max3800 3.2gbps adaptive equalizer and cable driver 4 _______________________________________________________________________________________ 20 3025 4035 5045 55 6560 70 02 03 040 10 50 60 70 80 90 supply current vs. temperature max3800 toc01 temperature ( c) supply current (ma) driver + equalizer equalizer driver 400 600500 900800 700 12001100 1000 1300 41 0 71 3 1 61922 cable driver output voltage vs. rmod max3800 toc02 r mod (k ) driver output voltage (mv) -50 -30-40 -10-20 10 0 20 4030 50 0 0.8 1.2 1.6 0.4 2.0 2.4 2.8 3.6 3.2 4.0 driver input return loss (s11) max3800 toc03 frequency (ghz) gain (db) -50 -30-40 -10-20 10 0 20 4030 50 0 0.8 1.2 1.6 0.4 2.0 2.4 2.8 3.6 3.2 4.0 driver output return loss (s22) max3800 toc04 frequency (ghz) gain (db) 30 35 4540 50 55 0.001 0.1 0.01 1 10 100 equalizer residual jitter vs. power supply noise (100mvp-p sine wave) (40ft of madison #14887 shielded twisted pair-differential) max3800 toc05 noise frequency (mhz) jitter (ps p-p ) 40 6050 8070 100 90 110 40 50 55 45 60 65 70 75 80 85 (inches) equalizer residual jitter vs. line length (fr-4 6mil stripline - single-ended) max3800 toc09 line length jitter (ps p-p ) 3.2gbps 622mbps 2.5gbps 1.02 1.27 1.40 1.14 1.52 1.65 1.77 1.90 2.03 2.16 (meters) 20 30 40 50 60 70 80 90 100 10 20 30 40 50 (feet) equalizer residual jitter vs. cable length (madison #13887 shielded twisted pair-differential) max3800 toc07 cable length jitter (ps p-p ) 3.2gbps 622mbps 2.5gbps 3.05 6.1 9.14 12.19 15.24 (meters) 40 8060 120100 140 160 25 55 65 35 45 75 85 95 (feet) equalizer residual jitter vs. cable length (rg179b 75 coaxial cable - single-ended) max3800 toc08 cable length jitter (ps p-p ) 3.2gbps 622mbps 2.5gbps 7.65 16.76 19.81 10.67 13.72 22.86 25.91 28.96 (meters) 70 80 100 90 120 130110 140 300 500 600 400 700 800 900 1000 1100 equalizer residual jitter vs. cable input amplitude (rg179b 75 coaxial cable - single-ended) max3800 toc06 cable input amplitude (mv) jitter (ps p-p ) 25 ft 72 ft t ypical operating characteristics (t a = +25?, v cc = +3.3v, all jitter measurements done at 3.2gbps, 700mv cable input with 2 13 -1 prbs pattern with 100 consecutive ones and 100 consecutive zeros substituted. note: test pattern produces near worst-case jitter results. results will vary with pattern, unless otherwise noted.) downloaded from: http:///
max3800 3.2gbps adaptive equalizer and cable driver _______________________________________________________________________________________ 5 equalizer input after 115ft of cable (top) equalizer output (bottom) max3800 toc10 equalizer output eye diagram after 115ft of 50 gore 89 cable (differential, 2 7 -1 prbs) max3800 toc11 60ps/div (2.5gbps) equalizer output eye diagram after 100ft of 75 rg179 cable (single-ended, 2 7 -1 prbs) max3800 toc12 68ps/div (2.5gbps) equalizer output eye diagram after 100ft of belden 9207 cable (differential, 2 7 -1 prbs) max3800 toc13 60ps/div (2.5gbps) 60ps/div (2.5gbps) equalizer output eye diagram after 50ft of madison #14887 shielded twisted pair cable (differential, 2 7 -1 prbs) max3800 toc14 1.2 1.51.4 1.3 1.6 1.7 1.8 04 0 30 10 20 50 60 70 80 90 100 cim voltage vs. cable length (rg179b 75 coaxial cable - single-ended) max3800 toc15 cable length (feet) cim voltage (v) cim- cim+ -50 -30-40 -10-20 10 0 20 4030 50 0 0.8 1.2 1.6 0.4 2.0 2.4 2.8 3.6 3.2 4.0 equalizer input return loss (s11) max3800 toc16 frequency (ghz) gain (db) -50 -30-40 -10-20 10 0 20 4030 50 0 0.8 1.2 1.6 0.4 2.0 2.4 2.8 3.6 3.2 4.0 equalizer output return loss (s22) max3800 toc17 frequency (ghz) gain (db) t ypical operating characteristics (continued) (t a = +25?, v cc = +3.3v, all jitter measurements done at 3.2gbps, 700mv cable input with 2 13 -1 prbs pattern with 100 consecutive ones and 100 consecutive zeros substituted. note: test pattern produces near worst-case jitter results. results will vary with pattern, unless otherwise noted.) downloaded from: http:///
detailed description the max3800 consists of a cable driver (transmitter)and an adaptive cable equalizer (receiver). the driver and equalizer are implemented on the same chip, but they are completely independent. the cable driver the cable driver accepts differential or single-endedcurrent-mode logic (cml) input data at rates up to 3.2gbps. the driver output is also implemented using cml. the maximum output amplitude can be adjusted over a typical range of 450mv to 870mv by changing the value of the rmod resistor between 10k and 20k (this resistor is connected between the rmod pin and ground). the adaptive cable equalizer the adaptive cable equalizer accepts differential cmlinput data at rates up to 3.2gbps and is capable of equalizing differential or single-ended signals. it auto- matically adjusts to attenuation levels of up to 30db at 1.6ghz (due to skin-effect losses in copper cable). the equalizer consists of a cml input buffer, a loss-of-sig- nal detector, a flat response amplifier, a skin-effectcompensation amplifier, a current-steering network, a dual power-detector feedback loop, an output limiting amplifier, and a cml output buffer ( figure 1 ). general theory of operation the shape of the power spectrum of a random bitstream can be described by the square of the sinc function, where sinc f = (sin f) / f. for sufficiently long bit patterns (nonrandom bit streams), sinc 2 (f) is a good approximation. from the shape of the sinc 2 (f) function, we can estimate the ratio of the power densities at anytwo frequencies. the max3800 adaptive equalizer employs this principle by incorporating a feedback loop that continuously monitors the power at two frequencies and dynamically adjusts the equalizer to maintain the correct power ratio. cml input and output buffers the input and output buffers are implemented usingcurrent-mode logic (cml). equivalent circuits are shown in f igures 2 and 3 . for details on interfacing with max3800 3.2gbps adaptive equalizer and cable driver 6 _______________________________________________________________________________________ pin name function 1, 3, 6, 11, 14 v cce equalizer power supply 2, 7, 10, 15, 23, 24, 26, 31 gnd ground 4 ein+ positive equalizer input, cml 5 ein- negative equalizer input, cml 8 cim- negative cable integrity monitor (cim) output 9 cim+ positive cable integrity monitor (cim) output 12 eout- negative equalizer output, cml 13 eout+ positive equalizer output, cml 16, 17 n.c. no connection. leave unconnected. 18 los equalizer loss-of-signal output, active-low 19, 22, 27, 30, 32 v ccd driver power supply 20 din+ positive driver input, cml 21 din- negative driver input, cml 25 rmod driver output modulation adjust. a resistor connected from this pin to gnd controls driver outputvoltage. 28 dout+ positive driver output, cml 29 dout- negative driver output, cml ep exposed pad ground. the exposed pad must be soldered to the circuit board ground plane for proper thermaland electrical performance. pin description downloaded from: http:///
max3800 3.2gbps adaptive equalizer and cable driver _______________________________________________________________________________________ 7 variable attenuator limitingamp cable driver flatresponse amp f max3800 loop filter |h(f)| |h(f)| variable attenuator 200mhz pwr detector 600mhz pwr detector cim- cim+ cml cml cml cml r mod ein dout eoutdin p0wer detector los current steering network skineffect compen- sation amp figure 1. functional diagram in- in+ gnd esd structures v cc 50 50 gnd esdstructures 62.5 62.5 out- out+ v cc figure 2. cml input equivalent circuit figure 3. cml output equivalent circuit downloaded from: http:///
max3800 cml, see maxim application note hfan-1.0, interfacing between cml, pecl, and lvds. flat response and skin-effect compensation amplifiers the buffered input waveform is fed equally to twoamplifiers?he flat response amplifier and the skin- effect compensation amplifier. the flat response ampli- fier has a constant gain over the entire frequency range of the device, and the skin-effect compensation amplifi- er has a gain characteristic that approximates the inverse of the skin-effect attenuation inherent in copper cable. the skin-effect attenuation, in db per unit length, is proportional to the square root of the frequency. the output currents from the two amplifiers are supplied to the current-steering network. note that when los asserts low, equalization is minimized. current-steering network the function of the current-steering network is to com-bine adjustable quantities of the output currents from the flat response and skin-effect compensation ampli- fiers to achieve a desired current ratio. the ratio adjust- ment is controlled by the dual power-detector feedback loop. the current-steering network is implemented with a pair of variable attenuators that feed into a current-summing node. the variable attenuators are used to attenuate the output currents of the flat response and skin-effect compensation amplifiers under control of the dual power-detector feedback loop. the outputs of the two attenuators are combined at the summing node and then fed to the output limiting amplifier and the feed- back loop. dual power-detector feedback loop the output of the current-steering network is applied tothe inputs of two frequency-specific power detectors. one of the power detectors is tuned to 200mhz and the other is tuned to 600mhz. the outputs of the two power detectors are applied to the inverting (200mhz power detector) and noninverting (600mhz power detector) inputs of the differential loop amplifier. the differential outputs of the loop amplifier control the variable attenu- ators in the current-steering network. output limiting amplifier the output limiting amplifier amplifies the signal fromthe current-steering network to achieve the specified output voltage swing. applications information refer to maxim application note hfdn-10.0, equalizing gigabit copper cable links with the max3800 (avail- able at www.maxim-ic.com ) for additional applications information. selecting rmod the cable driver output amplitude can be adjusted byconnecting a resistor with a value from 10k to 20k between the rmod pin and ground. the exact outputamplitude of the driver for a given value of rmod resis- tance is dependent on a number of factors. refer to the typical operating characteristics ?able driver output voltage vs. rmod?for typical values. cable integrity monitor (cim) the differential cim output current is directly propor- tional to the output current of the loop amplifier (which controls the current-steering network?ee detailed description ). this is an analog current output that indi- cates the amount of equalization that is being applied. a convenient way to monitor the cim current is to con- nect a 100k resistor from each of the cim outputs to ground, and then measure the voltage at the cim pins. the amount of equalization (and thus the cim output level) is affected by various factors, including cable type, cable length, signal bandwidth, etc. refer to the typical operating characteristics ?im voltage vs. cable length?for typical values under specific condi-tions. loss-of-signal ( l l o o s s ) output loss-of-signal is indicated by the los output. a low level on los indicates that the equalizer input signal power has dropped below a threshold. the los output indicates a loss of signal. when the equalizer no longerdetects a signal from the channel, the los output goes low. when there is sufficient input voltage to the chan-nel (typically greater that 650mv), los is high. the los output is suitable for indicating problems with the trans-mission link caused by, for example, a broken cable, a defective driver, or a lost connection to the equalizer. 3.2gbps adaptive equalizer and cable driver 8 _______________________________________________________________________________________ downloaded from: http:///
single-ended operation for single-ended operation of the cable driver or equal-izer, connect the unused input to ground through a series combination of a capacitor (of equal value to other ac-coupling capacitors) and a 50 resistor. note that the max3800 is specified for differential operation. layout considerations the max3800? performance can be significantlyaffected by circuit-board layout and design. use good high-frequency design techniques, including minimiz- ing ground inductance and using fixed-impedance transmission lines for the high-frequency data signals. power-supply decoupling capacitors should be placed as close as possible to v cc . max3800 3.2gbps adaptive equalizer and cable driver _______________________________________________________________________________________ 9 max3800 top view 32 28 29 30 31 25 26 27 gndv ccd dout-dout+ v ccd v ccd gndrmod 10 13 15 14 16 11 12 9 cim+ v cce gnd eout+ eout- gnd v cce n.c. 2 3 4 5 6 7 8 cim- gnd v cce ein- ein+ v cce gnd 1 v cce 17 18 19 20 21 22 23 gnd 24 gndv ccd din- din+v ccd n.c. los pin configuration downloaded from: http:///
max3800 3.2gbps adaptive equalizer and cable driver 10 ______________________________________________________________________________________ 32l qfn.eps package information (the package drawing(s) in this data sheet may not reflect the most current specifications. for the latest package outline info rmation go to www.maxim-ic.com/packages .) downloaded from: http:///
max3800 3.2gbps adaptive equalizer and cable driver ______________________________________________________________________________________ 11 package information (continued) (the package drawing(s) in this data sheet may not reflect the most current specifications. for the latest package outline info rmation go to www.maxim-ic.com/packages .) downloaded from: http:///
max3800 3.2gbps adaptive equalizer and cable driver 12 ______________________________________________________________________________________ 32l,tqfp.eps f 1 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 info rmation go to www.maxim-ic.com/packages .) downloaded from: http:///
max3800 3.2gbps adaptive equalizer and cable driver 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 ____________________ 13 2005 maxim integrated products printed usa is a registered trademark of maxim integrated products, inc. f 2 2 21-0079 package outline,32l tqfp, 5x5x1.0mm, ep option package infor mation (continued) (the package drawing(s) in this data sheet may not reflect the most current specifications. for the latest package outline info rmation go to www.maxim-ic.com/packages .) downloaded from: http:///

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