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general description the max3293/max3294/max3295 low-power, high- speed transmitters for rs-485/rs-422 commu - nication operate from a single +3.3v power supply. these devices contain one differential transmitter. the max3295 transmitter operates at data rates up to 20mbps, with an output skew of less than 5ns, and a guaranteed driver propagation delay below 25ns. the max3293 (250kbps) and max3294 (2.5mbps) are slew-rate limited to minimize emi and reduce reflections caused by improperly terminated cables. the max3293/max3294/max3295 output level is guar - anteed at +1.5v with a standard 54 ? load, compliant with rs-485 specifications. the transmitter draws 5ma of supply current when unloaded, and 1a in low-power shutdown mode (de = gnd). hot-swap circuitry eliminates false transitions on the data cable during circuit initialization or connection to a live backplane, and short-circuit current limiting and ther - mal-shutdown circuitry protect the driver against exces - sive power dissipation. the max3293/max3294/max3295 are offered in a 6-pin sot23 package, and are specified over the automotive temperature range. applications rs-485/rs-422 communications clock distribution telecom equipment automotive security equipment point-of-sale equipment industrial control features space-saving 6-pin sot23 package 250kbps/2.5mbps/20mbps data rates available operate from a single +3.3v supply esd protection 9kvChuman body model slew-rate limited for errorless data transmission (max3293/max3294) 1a low-current shutdown mode -7v to +12v common-mode input voltage range current limiting and thermal shutdown for driver-overload protection hot-swap inputs for telecom applications automotive temperature range (-40c to +125c) pin configuration appears at end of data sheet. +denotes a lead(pb)-free/rohs-compliant package. t = tape and reel. /v denotes automotive-qualified package. part maximum data rate (mbps) slew- rate limited top mark max3293aut+t 0.25 yes abni or abvh max3294aut+t 2.5 yes abnj or abvi max3295aut+t 20 no abnk or abvj max3295aut/v+t 20 no +acsb part temp range pin-package max3293 aut+t -40c to +125c 6 sot23-6 max3294 aut+t -40c to +125c 6 sot23-6 max3295 aut+t -40c to +125c 6 sot23-6 max3295 aut/v+t -40c to +125c 6 sot23-6 max3293max3294 max3295 d di de max3280emax3281e max3283e max3284e r ro 120 ? zy max3293Cmax3295 20mbps, +3.3v, sot23 rs-485/ rs-422 transmitters 19-2770; rev 4; 12/14 selector guide ordering information typical operating circuit downloaded from: http:///
(all voltages referenced to gnd, unless otherwise noted.) supply voltage (v cc ) ............................................................ +6v de, di ...................................................................... -0.3v to +6v y, z ........................................................................ -7v to +12.5v maximum continuous power dissipation (t a = +70c) sot23 (derate 8.2mw/c above +70c) ................. 654.1mw operating temperature ranges max32_ _aut .............................................. -40c to +125c storage temperature range ............................ -65c to +160c junction temperature ..................................................... +160c lead temperature (soldering, 10s) ................................. +300c soldering temperature (reflow) ....................................... +260c (v cc = +3.3v 5%, t a = t min to t max , unless otherwise noted. typical values are at v cc = +3.3v and t a = +25c.) (notes 1, 2) parameter symbol conditions min typ max units power supply supply voltage v cc 3.135 3.300 3.465 v supply current in normaloperation i q no load, di = v cc or gnd, de = v cc 5 ma supply current in shutdown mode i shdn no load, de = gnd 1 10 a driver differential driver output v od figure 1, de = v cc , di = gnd or v cc r = 50 ? (rs-422), t a +85c 2.0 v cc v r = 27 ? (rs-485), t a +85c 1.5 v cc change in magnitude ofdifferential output voltage ? vod figure 1, r = 27 ? or 50 ? , de = v cc (note 3) 0.2 v driver common-modeoutput voltage v oc figure 1, r = 27 ? or 50 ? , de = v cc , di = v cc or gnd -1 +3 v change in magnitude ofcommon-mode voltage ?v oc figure 1, r = 27 ? or 50 ? (note 3) 0.2 v driver logic input high voltage v ih de, di 2.0 v input low voltage v il de, di 0.8 v input current i in de, di -2 +2 a output leakage i o y, zde = gnd, v cc = gnd or +3.3v v in = +12v -20 +20 a v in = -7v -20 +20 driver short-circuit foldbackoutput current i osfd (v cc - 1v) v out +12v, output high +25 ma -7v v out 1v, output high -25 driver short-circuitoutput current i osd 0 v out +12v, output low -250 ma -7v v out v cc , output high +250 thermal-shutdown threshold t ts 160 c thermal-shutdown hysteresis t tsh 40 c esd protection y, z human body model 9 kv max3293Cmax3295 20mbps, +3.3v, sot23 rs-485/ rs-422 transmitters www.maximintegrated.com maxim integrated 2 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. absolute maximum ratings downloaded from: http:///
(v cc = +3.3v 5%, t a = +25c, unless otherwise noted. typical values are at v cc = +3.3v.) (v cc = +3.3v 5%, t a = +25c, unless otherwise noted. typical values are at v cc = +3.3v.) parameter symbol conditions min typ max units driver propagation delay t plh figures 2, 3; r diff = 54 ? , c l = 50pf 24 70 ns t phl 24 70 driver differential output rise orfall time t r figures 2, 3; r diff = 54 ? , c l = 50pf 10 70 ns t f 10 70 driver-output skew t skew figures 2, 3; r diff = 54 ? , c l = 50pf, t skew = | t plh - t phl | (note 5) -40 +40 ns differential driver-output skew t dskew figures 2, 3; r diff = 54 ? , c l = 50pf -6 +6 ns maximum data rate figures 2, 3; r diff = 54 ? , c l = 50pf 2.5 mbps driver enable to output high t zh figures 4, 5; s2 closed, r l = 500 ? , c l = 100pf 400 ns driver enable to output low t zl figures 4, 5; s1 closed, r l = 500 ? , c l = 100pf 400 ns driver disable time from low t lz figures 4, 5; s1 closed, r l = 500 ? , c l = 100pf 100 ns driver disable time from high t hz figures 4, 5; s2 closed, r l = 500 ? , c l = 100pf 100 ns device-to-device propagationdelay matching same power supply, maximum temperaturedifference between devices = +30c (note 5) 46 ns parameter symbol conditions min typ max units driver propagation delay t plh figures 2, 3; r diff = 54 ? , c l = 50pf 400 1300 ns t phl 400 1300 driver differential output riseor fall time t r figures 2, 3; r diff = 54 ? , c l = 50pf 400 1200 ns t f 400 1200 driver-output skew t skew figures 2, 3; r diff = 54 ? , c l = 50pf, t skew = | t plh - t phl | (note 5) -400 +400 ns differential driver-output skew t dskew figures 2, 3; r diff = 54 ? , c l = 50pf -100 +100 ns maximum data rate figures 2, 3; r diff = 54 ? , c l = 50pf 250 kbps driver enable to output high t zh figures 4, 5; s2 closed, r l = 500 ? , c l = 100pf 2000 ns driver enable to output low t zl figures 4, 5; s1 closed, r l = 500 ? , c l = 100pf 2000 ns driver disable time from low t lz figures 4, 5; s1 closed, r l = 500 ? , c l = 100pf 1000 ns driver disable time from high t hz figures 4, 5; s2 closed, r l = 500 ? , c l = 100pf 1000 ns device-to-device propagationdelay matching same power supply, maximum temperaturedifference between devices = +30c (note 5) 900 ns max3293Cmax3295 20mbps, +3.3v, sot23 rs-485/ rs-422 transmitters www.maximintegrated.com maxim integrated 3 switching characteristics (max3294) switching characteristics (max3293) downloaded from: http:///
note 1: devices production tested at +25c. limits over the operating temperature range are guaranteed by design. note 2: all currents into the device are positive; all currents out of the device are negative. all voltages are referenced to device ground, unless otherwise noted. note 3: ?v od and ?v oc are the changes in v od and v oc , respectively, when the di input changes state. note 4: the maximum current applies to peak current just prior to foldback current limiting. note 5: guaranteed by design; not production tested. (v cc = +3.3v 5%, t a = +25c, unless otherwise noted. typical values are at v cc = +3.3v.) parameter symbol conditions min typ max units driver propagation delay t plh figures 2, 3; r diff = 54 ? , cl = 50 pf 25 ns t phl 25 driver differential output riseor fall time t r figures 2, 3;r diff = 54 ? , c l = 50pf t a = -40c to +125c 18.5 ns t a < +85c 15 t f t a = -40c to +125c 18.5 t a < +85c 15 driver-output skew t skew figures 2, 3; r diff = 54 ? , c l = 50pf, t skew = | t plh - t phl | 5 ns differential driver-output skew t dskew figures 2, 3; r diff = 54 ? , c l = 50pf 5 ns maximum data rate figures 2, 3; r diff = 54 ? , c l = 50pf, t a +85c 20 mbps figures 2, 3; r diff = 54 ? , c l = 50pf 16 driver enable to output high t zh figures 4, 5; s2 closed, r l = 500 ? , c l = 100pf 400 ns driver enable to output low t zl figures 4, 5; s1 closed, r l = 500 ? , c l = 100pf 400 ns driver disable time from low t lz figures 4, 5; s1 closed, r l = 500 ? , c l = 100pf 100 ns driver disable time from high t hz figures 4, 5; s2 closed, r l = 500 ? , c l = 100pf 100 ns device-to-device propagationdelay matching same power supply, maximum temperaturedifference between devices = +30c (note 5) 25 ns max3293Cmax3295 20mbps, +3.3v, sot23 rs-485/ rs-422 transmitters www.maximintegrated.com maxim integrated 4 switching characteristics (max3295) downloaded from: http:///
figure 5. driver enable and disable times figure 4. enable/disable timing test load figure 3. driver propagation delays figure 2. driver timing test circuit figure 1. driver dc test load output normally low output normally high 3v0v y, z v ol y, z 0v 1.5v 1.5v v ol + 0.25v v oh - 0.25v 2.3v 2.3v t zl(shdn) , t zl t lz t zh(shdn) , t zh t hz de s1s2 output under test v cc c l r l di 3v0v z y v o 0v -v o v o 1.5v 1/2 v o 1/2 v o t plh t f t r t phl 10% 90% 90% 1.5v 10% v diff = v (y) - v (z) t skew = | t plh - t phl | v diff f = 1mhz, t r 3ns, t f 3ns di de 3v y v id c l c l r diff z y z v od rr v oc max3293Cmax3295 20mbps, +3.3v, sot23 rs-485/ rs-422 transmitters www.maximintegrated.com maxim integrated 5 test circuits and timing diagrams downloaded from: http:///
(v cc = +3.3v, t a = +25c, unless otherwise noted.) 0 10 20 30 40 max3293-95 toc09 temperature (c) propagation delay (ns) -40 20 50 80 -10 110 driver propagation delay vs. temperature t phl t plh r diff = 54 ? c l = 50pf 0 1 2 3 4 output skew vs. temperature max3293-95 toc08 temperature (c) output skew (ns) -40 20 50 80 -10 110 driver-output current vs. driver-output high voltage max3293-95 toc07 output high voltage (v) output current (ma) 0 -100 -40-60 -80 -20 -120 -7 -5 -3 -1 1 3 5 20 driver-output current vs. driver-output low voltage max3293-95 toc06 output low voltage (v) output current (ma) 20 8060 40 100 0 0 2 4 6 8 10 12 140120 1.0 2.0 2.5 3.0 3.5 max3293-95 toc05 temperature (c) differential output voltage (v) -40 20 50 80 -10 110 driver differential output voltage vs. temperature r diff = 54 ? r diff = 100 ? 1.5 0 10 3020 40 50 output current vs. differential output voltage max3293-95 toc04 differential output voltage (v) output current (ma) 1.75 2.75 2.25 2.50 2.00 3.00 3.25 3.50 0 1.61.2 0.8 0.4 2.0 max3293-95 toc03 temperature (c) supply current ( a) -40 20 50 80 -10 110 shutdown supply current vs. temperature de = gnd 0 0.5 1.0 1.5 2.0 supply current vs. temperature max3293-95 toc02 temperature (c) supply current (ma) -40 20 50 80 -10 110 de = v cc no loadno switching 0 5 10 2015 25 max3295 supply current vs. data rate max3293-95 toc01 data rate (mbps) supply current (ma) 0 10 5 15 20 de = v cc no load t a = +85c t a = +125c t a = +25c t a = -40c max3293Cmax3295 20mbps, +3.3v, sot23 rs-485/ rs-422 transmitters maxim integrated 6 www.maximintegrated.com typical operating characteristics downloaded from: http:///
(v cc = +3.3v, t a = +25c, unless otherwise noted.) pin name function 1 di driver input. a logic low on di forces the noninverting output (y) low and the inverting output (z) high. a logic high on di forces the noninverting output (y) high and the inverting output (z) low. 2 v cc positive supply. v cc = +3.3v 5%. bypass v cc to gnd with a 0.1f capacitor. 3 de driver output enable. force de high to enable driver. pull de low to disable the driver. hot-swap input, see the hot-swap capability section. 4 z inverting rs-485/rs-422 output 5 gnd ground 6 y noninverting rs-485/rs-422 output eye diagram (f in = 20mbps) max3293-95 toc14 10ns/div y, z: 500mv/div 0v y, z loaded driver-output waveform (f in = 16mbps) max3293-95 toc13 20ns/div y, z: 500mv/div 0v y, z unloaded driver-output waveform (f in = 16mbps) max3293-95 toc12 20ns/div y, z: 1v/div 0v y, z enable response time max3293-95 toc11 40ns/div de 0v0v y-z y, z, de: 2v/div driver propagation delay max3293-95 toc10 20ns/div y, z: 1v/divdi: 2v/div di 0v0v y, z max3293Cmax3295 20mbps, +3.3v, sot23 rs-485/ rs-422 transmitters maxim integrated 7 www.maximintegrated.com pin description typical operating characteristics (continued) downloaded from: http:///
detailed description the max3293/max3294/max3295 are low-power trans - mitters for rs-485/rs-422 communication. the max3295 operates at data rates up to 20mbps, the max3294 up to 2.5mbps (slew-rate limited), and the max3293 up to 250kbps (slew-rate limited). these devices are enabled using an active-high driver enable (de) input. when disabled, outputs enter a high-impedance state, and the supply current reduces to 1a. the max3293/max3294/max3295 have a hot-swap input structure that prevents disturbance on the differential signal lines when a circuit board is plugged into a hot back - plane (see the hot-swap capability section). drivers are also short-circuit current limited and are protected against excessive power dissipation by thermal-shutdown circuitry. driver the driver accepts a single-ended, logic-level input (di) and translates it to a differential rs-485/rs-422 level output (y and z). driving de high enables the driver, while pulling de low places the driver outputs (y and z) into a high-impedance state (see table 1). low-power shutdown force de low to disable the max3293/max3294/ max3295. in shutdown mode, the device consumes a maximum of 10a of supply current. hot-swap capability hot-swap input when circuit boards are inserted into a hot or pow - ered backplane, disturbances to the enable can lead to data errors. upon initial circuit board insertion, the processor undergoes its power-up sequence. during this period, the output drivers are high impedance and are unable to drive the de input of the max3293/ max3294/max3295 to a defined logic level. leakage currents up to 10a from the high-impedance out - put could cause de to drift to an incorrect logic state. additionally, parasitic circuit board capacitance could cause coupling of v cc or gnd to de. these factors could improperly enable the driver. the max3293/max3294/max3295 eliminate all above issues with hot-swap circuitry. when v cc rises, an inter - nal pulldown circuit holds de low for approximately 10s. after the initial power-up sequence, the pulldown circuit becomes transparent, resetting the hot-swap tolerable input. figure 7. differential power-up glitch (0.1v/s) figure 6. simplified structure of the driver enable input (de) x = dont care. table 1. max3293/max3294/ max3295 (rs-485/rs-422) transmitting function table inputs outputs de di y z 0 x shutdown shutdown 1 0 0 1 1 1 1 0 differential power-up glitch (0.1v/ s) 4 s/div 2v/div v cc y z y-z 0v10mv/div ac-coupled 10mv/div ac-coupled 20mv/div v cc timer timer en de (hot swap) 10 s 100 a m1 m2 5.6k ? 2ma max3293Cmax3295 20mbps, +3.3v, sot23 rs-485/ rs-422 transmitters www.maximintegrated.com maxim integrated 8 downloaded from: http:///
hot-swap input circuitry the max3293/max3294/max3295 enable input fea - tures hot-swap capability. at the input, there are two nmos devices, m1 and m2 (figure 6). when v cc ramps from zero, an internal 10s timer turns on m2 and sets the sr latch, which also turns on m1. transistors m2, a 2ma current sink, and m1, a 100a current sink, pull de to gnd through a 5.6k ? resistor. m2 is designed to pull de to the disabled state against an external parasitic capacitance up to 100pf that may drive de high. after 10s, the timer deactivates m2 while m1 remains on, holding de low against three- state leakages that can drive de high. m1 remains on until an external source overcomes the required input current. at this time, the sr latch resets and m1 turns off. when m1 turns off, de reverts to a standard, high-impedance cmos input. whenever v cc drops below 1v, the hot-swap input is reset. hot-swap line transient during a hot-swap event when the driver is connected to the line and is powered up, the driver must not cause the differential signal to drop below 200mv. figures 7, 8, and 9 show the results of the max3295 during power-up for three different v cc ramp rates (0.1v/s, 1v/s, and 10v/ s). the photos show the v cc ramp, the single-ended signal on each side of the 100 ? termination, as well as the differential signal across the termination. esd protection human body model figure 10 shows the human body model, and figure 11 shows the current waveform it generates when discharged into low impedance. this model consists of a 100pf capac - itor charged to the esd voltage of interest, which is then discharged into the device through a 1.5k ? resistor. figure 11. current waveform figure 10. human body esd test figure 9. differential power-up glitch (10v/s) figure 8. differential power-up glitch (1v/s) i p 100% 90% 36.8% t rl time t dl current waveform peak-to-peak ringing(not drawn to scale) i r 10% 0v 0v amperes charge-current- limit resistor discharge resistance storagecapacitor c s 100pf r c 1m ? r d 1.5k ? high- voltage dc source device under test differential power-up glitch (10v/ s) 200ns/div 2v/div v cc y z y-z 0v50mv/div ac-coupled 50mv/div ac-coupled 100mv/div differential power-up glitch (1v/ s) 1 s/div 2v/div v cc y z y-z 0v100mv/div ac-coupled 100mv/div ac-coupled 200mv/div max3293Cmax3295 20mbps, +3.3v, sot23 rs-485/ rs-422 transmitters www.maximintegrated.com maxim integrated 9 downloaded from: http:///
reduced emi and relections (max3293/max3294) the max3293/max3294 are slew-rate limited, minimizing emi and reducing reflections caused by improperly ter - minated cables. figure 12 shows fourier analysis of the max3295 transmitting a 125khz signal. high-frequency harmonics with large amplitudes are evident. figure 13 shows the same information, but for the slew-rate-limited max3293, transmitting the same signal. the high-fre - quency harmonics have much lower amplitudes, and the potential for emi is significantly reduced. to minimize reflections, the line should be terminated at both ends in its characteristic impedance, and stub lengths off the main line should be kept as short as possible. the slew-rate-limited max3293 and max3294 are more toler - ant of imperfect termination. driver-output protection two mechanisms prevent excessive output current and power dissipation caused by faults or by bus contention. the first, a foldback current limit on the output stage, provides immediate protection against short circuits over the whole common-mode voltage range (see the typical operating characteristics ). the second, a thermal-shut - down circuit, forces the driver outputs into a high-imped - ance state if the die temperature exceeds +160c. figure 13. driver-output waveform and fft plot of max3293 transmitting a 125khz signal figure 12. driver-output waveform and fft plot of max3295 transmitting a 125khz signal package type package code outline no. land pattern no. 6 sot23 u6cn+2 21-0058 90-0175 v cc z de 1 6 y + 5 gnd di max3293max3294 max3295 sot23-6 top view 2 3 4 driver-output waveform and fft plot of max3293 10db/div driver-output waveform and fft plot of max3295 10db/div max3293Cmax3295 20mbps, +3.3v, sot23 rs-485/ rs-422 transmitters www.maximintegrated.com maxim integrated 10 package information for the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages . note that a +, #, or - in the package code indicates rohs status only. package drawings may show a different suffix character, but the drawing pertains to the package regardless of rohs status. chip information process: bicmos pin coniguration downloaded from: http:///
revision number revision date description pages changed 3 3/11 added lead-free parts to the ordering information and selector guide tables 1 4 12/14 added max3295aut/v+t to ordering information 1 maxim integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim integrated product. no circuit patent licenses are implied. maxim integrated reserves the right to change the circuitry and speciications without n otice at any time. the parametric values (min and max limits) shown in the electrical characteristics table are guaranteed. other parametric values quoted in this data sheet are provided for guidance. maxim integrated and the maxim integrated logo are trademarks of maxim integrated products, inc. max3293Cmax3295 20mbps, +3.3v, sot23 rs-485/ rs-422 transmitters ? 2014 maxim integrated products, inc. 11 revision history for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxim integrateds website at www.maximintegrated.com. downloaded from: http:///

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