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general description the max3388e/max3389e are 2.5v-powered eia/tia-232 and v.28/v.24 communications interfaces with low power requirements, high data-rate capabilities, and enhanced electrostatic discharge (esd) protection. the max3388e/max3389e have two receivers and three transmitters. all rs-232 inputs and outputs are protected to ?5kv using the iec 1000-4-2 air-gap discharge method, ?kv using the iec 1000-4-2 contact discharge method, and ?5kv using the human body model. in addition to the traditional rs-232 i/o, these devices have dedicated logic-level i/o pins for additional device-to- device handshaking. during shutdown the logic-level i/o pins are active for the max3389e. an internal 62 switch is provided to switch power to external circuitry or modules.a proprietary low-dropout transmitter output stage enables rs-232 compatible performance from a +2.35v to +3.0v supply with a dual charge pump. the charge pump requires only four small 0.1? capacitors for oper- ation from a +2.5v supply. the max3388e/max3389e are capable of running at data rates up to 460kbps while maintaining rs-232-compatible output levels. the max3388e/max3389e have a unique v l pin that allows interoperation in mixed-logic voltage systems.both input and output logic levels are pin programma- ble through the v l pin. the max3388e/max3389e are available in a space-saving tssop package. features ? v l pin for compatibility with mixed-voltage systems ? additional i/o for hot-sync applications ? ?5kv esd protection on rx inputs, tx outputs,lin, and swin ? low 300? supply current ? guaranteed 460kbps data rate ? 1? low-power shutdown ? integrated switch for powering remote circuitry ? flow-through pinout ? l out active during shutdown (max3389e) applications subnotebook/palmtop computerspdas and pda cradles cell phone data cables battery-powered equipment hand-held equipment peripherals max3388e/max3389e 2.5v, 15kv esd-protected rs-232 transceivers for pdas and cell phones ________________________________________________________________ maxim integrated products 1 2423 22 21 20 19 18 17 12 3 4 5 6 7 8 shdnv cc gndt1out c2+ c1- v+ c1+ top view t2outt3out r1in r2in t2in t1in v- c2- 1615 14 13 9 1011 12 linswin v l r1out r2out swout lout t3in tssop max3388emax3389e typical operating circuit 19-1845; rev 1; 9/01 pin configuration ordering information part temp. range pin-package max3388e cug 0? to +70? 24 tssop max3388eeug -40? to +85? 24 tssop max3389e cug 0? to +70? 24 tssop max3389eeug -40? to +85? 24 tssop max3388emax3389e r2out 12 r1out v l 13 r2in 17 gnd 22 rs-232i/o t2in 8 t1in 7 c2- 5 c2+ 4 c1- 3 c1+ 1 r1in 18 t2out 20 t1out 21 v- 6 v+ 2 v cc v l 14 23 c1 0.1 f c2 0.1 f c bypass +2.5v t3in 9 t3out 19 5k 5k c30.1 f c40.1 f v l 24 shdn swin 15 16 lin 30k 11 swout shdn 10 lout = 15kv esd protection c;4. 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:///
max3388e/max3389e 2.5v, 15kv esd-protected rs-232 transceivers for pdas and cell phones 2 _______________________________________________________________________________________ absolute maximum ratings dc electrical characteristics (v cc = v l = +2.35v to +3.0v, c1?4 = 0.1?, t a = t min to t max , unless otherwise noted. typical values are at v cc = v l = +2.5v, t a = +25?.) 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. note 1: v+ and v- can have maximum magnitudes of 7v, but their absolute difference cannot exceed 13v. v cc to gnd ..............................................................-0.3v to +6v v l to gnd...................................................-0.3v to (v cc + 0.3v) v+ to gnd ................................................................-0.3v to +7v v- to gnd .................................................................+0.3v to -7v v+ + ? v- ? (note 1) ............................................................... +13v input voltages t_in, shdn, lin to gnd.......................................-0.3v to +6v r_in to gnd .....................................................................?5v swin to gnd...........................................-0.3v to (v cc + 0.3v) output voltages t_out to gnd...............................................................?3.2v r_out, swout, lout to gnd ................-0.3v to (v l + 0.3v) short-circuit duration t_out to gnd........................continuous continuous power dissipation (t a = +70?) 24-pin tssop (derate 12.2mw/? above +70?) ........975mw operating temperature ranges max338_ecug ...................................................0? to +70? max338_eeug.................................................-40? to +85? junction temperature ......................................................+150? storage temperature range .............................-65? to +150? lead temperature (soldering, 10s) .................................+300? parameter symbol shutdown supply current supply current input logic low input logic high transmitter input hysteresis input leakage current output leakage current output voltage low output voltage high input voltage range input threshold low input threshold high input hysteresis input resistance t a = +25? i out = -1ma i out = 1.6ma r_out, shdn = 0 v l = +2.5v v l = +2.5v shdn = v cc , no load shdn = gnd, all inputs at gnd conditions min typ max 11 0 0.3 1 units ? ma 0.6 v 1.5 v 0.4 v ? ?.01 ? ? ?.05 ?0 0.4 v v l - v l - 0.6 0.13 v -25 +25 v 0.6 1.1 v v 1.8 2.4 v k 0.7 357 all transmitter outputs loaded with 3k to ground output voltage swing ?.7 ?.2 output resistance v cc = 0, transmitter output = ?v 300 10m output short-circuit current v t_out = 0 ma ?0 dc characteristics (v cc = +2.5v, t a = +25?) logic inputs (t_in, shdn ) receiver outputs receiver inputs transmitter outputs v t a = +25?, v l = +2.5v t a = +25?, v l = +2.5v downloaded from: http:///
max3388e/max3389e 2.5v, 15kv esd-protected rs-232 transceivers for pdas and cell phones _______________________________________________________________________________________ 3 timing characteristics (v cc = v l = +2.35v to +3.0v, c1?4 = 0.1?, t a = t min to t max , unless otherwise noted. typical values are at v cc = v l = +2.5v, t a = +25?.) ? t phl - t plh ? note 2: guaranteed by correlation. note 3: transmitter skew is measured at the transmitter zero crosspoint. dc electrical characteristics (continued)(v cc = v l = +2.35v to +3.0v, c1?4 = 0.1?, t a = t min to t max , unless otherwise noted. typical values are at v cc = v l = +2.5v, t a = +25?.) parameter maximum data rate receiver propagation delay receiver output enable time receiver output disable time time to exit shutdown transmitter skew receiver skew transition-region slew rate ? t phl - t plh ? t plh t phl symbol conditions r l = 3k , c l = 1000pf, one transmitter switching receiver input to receiver output, c l = 150pf ? v t_out ? > 3.7v r l = 3k , c l = 1000pf (note 3) v cc = +2.5v, t a = +25?, r l = 3k to 7k , measured from +3v to -3v or -3v to +3v, one transmitter switching c l = 150pf to 1000pf c l = 150pf to 2500pf 43 0 63 0 50 100 30 200 200 0.15 0.15 250 min typ max units kbps ? ns ns ? ns ns v/? parameter symbol conditions min typ max units output leakage current v t_out = ?2v, transmitters disabled, v cc = 0 or +2.5v ?5 ? handshaking i/o (lin, lout) input voltage range 0v cc v input threshold low lin, v l = +2.5v, t a = +25 c 0.6 1.1 v input threshold high lin, v l = +2.5v, t a = +25 c 1.7 2 v input hysteresis 0.6 v input resistance t a = +25 o c2 0 4 0 k output voltage low lout, i sink = 1.6ma 0.4 v output leakage current lout = v l , lin = low or float 10 ? switch (swin, swout) input voltage range 0v cc v on-resistance 62 100 off-leakage current shdn = 0 1 a turn-on time 0.18 ? turn-off time 0.7 ? esd protection human body model ?5 iec 1000-4-2 air-gap discharge method ?5 r_in, t_out, lin, swinesd protection iec 1000-4-2 contact discharge method ? kv r l = 3k , c l = 150pf, one transmitter switching (note 2) 460 ? t phl - t plh ? downloaded from: http:///
max3388e/max3389e 2.5v, 15kv esd-protected rs-232 transceivers for pdas and cell phones 4 _______________________________________________________________________________________ typical operating characteristics (v cc = v l = +2.5v, t a = +25 c, unless otherwise noted.) -5.0 -2.5 2.5 0 5.0 0 2000 1000 3000 4000 5000 transmitter output voltage vs. load capacitance max3388e toc01 load capacitance (pf) output voltage (v) data rate = 460kbpsload = 3k in parallel 0 2 4 6 8 10 12 14 16 0 1000 2000 3000 4000 5000 slew rate vs. load capacitance max3386e toc02 load capacitance (pf) slew rate (v/ s) slew rate + slew rate - -5.0 -2.5 2.5 0 5.0 0 100 150 200 250 50 300 350 400 450 transmitter output voltage vs. data rate max3388e toc03 data rate (kbps) output voltage (v) load = 3k , 1000pf one transmitter switchingat data rate, other transmitters at 1/8 data rate 0 2010 4030 50 60 0 2000 1000 3000 4000 5000 supply current vs. load capacitance max3388e toc04 load capacitance (pf) supply current (ma) load = 3k one transmitter switchingat data rate, other transmitters at 1/8 data rate 460kbps 240kbps 20kbps lin to lout t pd max3388e toc05 200ns/div r pullup = 1k lout 1v/div lin 45 50 6055 65 70 0 1.0 0.5 1.5 2.0 2.5 on-resistance vs. swin voltage max3388e toc06 v swin (v) r on ( ) t a = +85 c t a = +25 c t a = -40 c downloaded from: http:///
max3388e/max3389e 2.5v, 15kv esd-protected rs-232 transceivers for pdas and cell phones _______________________________________________________________________________________ 5 pin description pin name function 1 c1+ positive terminal of the voltage-doubler charge-pump capacitor 2 v+ +4.2v supply generated by the charge pump 3 c1- negative terminal of the voltage-doubler charge-pump capacitor 4 c2+ positive terminal of the inverting charge-pump capacitor 5 c2- negative terminal of the inverting charge-pump capacitor 6 v- -4.2v supply generated by the charge pump 7, 8, 9 t1in, t2in, t3in cmos transmitter inputs 10 lout handshaking output. this output is active during shutdown for the max3389e. 11 swout switch output 12, 13 r2out, r1out cmos receiver outputs. swing between 0 and v l . 14 v l logic-level supply. all cmos inputs and outputs are referred to this supply. v l = +1.8v to +3.0v. 15 swin switch input. 16 lin handshaking input. this input is active during shutdown for the max3389e. 17, 18 r2in, r1in rs-232 receiver inputs 19, 20, 21 t3out,t2out, t1out rs-232 transmitter outputs 22 gnd ground 23 v cc +2.35v to +3v supply voltage 24 shdn shutdown input. 0 = shutdown, switch open; 1 = normal operation, switch closed. downloaded from: http:///
max3388e/max3389e 2.5v, 15kv esd-protected rs-232 transceivers for pdas and cell phones 6 _______________________________________________________________________________________ detailed description dual charge-pump voltage converter the max3388e/max3389e s internal power supply consists of a regulated dual charge pump that providesoutput voltages of +4.2v (doubling charge pump) and - 4.2v (inverting charge pump), regardless of the input voltage (v cc ) over a +2.5v to +3.0v range. the charge pumps operate in a discontinuous mode: if the output voltages are less than 4.2v, the charge pumps areenabled; if the output voltages exceed 4.2v, the charge pumps are disabled. each charge pump requires flying capacitors (c1, c2) and reservoir capacitors (c3, c4) to generate the v+ and v- supplies. rs-232 transmitters the transmitters are inverting level translators that convertcmos-logic levels to ?.7v eia/tia-232-compatible levels. the max3388e/max3389e s transmitters guarantee a 250kbps data rate with loads of 3k in parallel with 1000pf and 460kbps data rate with loads of 3k in paral- lel with 150pf. figure 1 shows a complete system con-nection. these rs-232 output stages are turned off (high impedance) when the devices are in shutdown mode. when the power is off, the max3388e /max3389e permit the outputs to be driven up to ?2v. the transmitter inputs do not have pullup resistors.connect unused inputs to gnd or v l . rs-232 receivers the receivers convert rs-232 signals to cmos-logicoutput levels. the max3388e/max3389e s receivers have inverting outputs. the outputs are high imped-ance in shutdown. shutdown mode supply current falls to less than 1? when themax3388e /max3389e are placed in shutdown mode ( shdn logic low). when shut down, the device s charge pumps are turned off, v+ decays to v cc , v- is pulled to ground, the switch is opened, and the transmitter outputsare disabled (high impedance). the time required to exit max3388emax3389e i/o chip with uart cpu rs-232 power- management unit or keyboard controller shdn v l i/o chip power supply figure 1. interface under control of pmu 10 s/div 5v/div 2v/div t1 t2 v cc = +2.5v c1?4 = 0.1 f c l = 1000pf, r l = 3k figure 2. transmitter outputs when exiting shutdown table 1. shutdown logic truth table lout shdn t r an sm it t er o u tpu t s receiver outputs ch arg e pu m p swit c h max3388e max3389e l high-z high-z inactive open high-z lin h active active active closed lin lin downloaded from: http:///
max3388e/max3389e 2.5v, 15kv esd-protected rs-232 transceivers for pdas and cell phones _______________________________________________________________________________________ 7 shutdown is typically 30?, as shown in figure 2.connect shdn to v cc if the shutdown mode is not used. in shutdown mode, the receiver outputs are high imped-ance (table 1). v l logic supply input unlike other rs-232 interface devices where the receiveroutputs swing between 0 and v cc , the max3388e/ max3389e feature a separate logic supply input (v l ) that sets v oh for the receiver outputs and sets thresh- olds for the transmitter inputs. this feature allows agreat deal of flexibility in interfacing to many different types of systems with different logic levels. connect this input to the host logic supply (1.8v v l v cc ). also see the typical pda/cell-phone application sec- tion. 15kv esd protection as with all maxim devices, esd-protection structures areincorporated on all pins to protect against esds encoun- tered during handling and assembly. the max3388e/ max3389e s driver outputs, receiver inputs, the hand- shaking input lin, and the switch terminal swin haveextra protection against static electricity. maxim has developed state-of-the-art structures to protect these pins against an esd of ?5kv without damage. the esd structures withstand high esd in all states: normal opera- tion, shutdown, and powered down. after an esd event, maxim s e version devices keep working without latchup, whereas competing rs-232 products can latchand must be powered down to remove latchup. esd pro- tection can be tested in various ways. the transmitter out- puts and receiver inputs of this product family are characterized for protection to the following limits: 1) ?5kv using the human body model 2) ?kv using the contact discharge method specified in iec 1000-4-2 3) ?5kv using iec 1000-4-2 s air-gap discharge method esd test conditions esd performance depends on a variety of conditions.contact maxim for a reliability report that documents test setup, methodology, and results. human body model figure 3a shows the human body model, and figure 3bshows the current waveform it generates when dis- charged into a low impedance. this model consists of a 100pf capacitor charged to the esd voltage of interest, which is then discharged into the test device through a 1.5k resistor. iec 1000-4-2 the iec 1000-4-2 standard covers esd testing andperformance of finished equipment; it does not specifi- cally refer to ics. the max3388e/max3389e helps you design equipment that meets level 4 (the highest level) of iec 1000-4-2, without the need for additional esd- protection components. the major difference between tests done using the human body model and iec 1000-4-2 is higher peak current in iec 1000-4-2, because series resistance is lower in the iec 1000-4-2 model. hence, the esd with- stand voltage measured to iec 1000-4-2 is generally lower than that measured using the human body model. figure 4a shows the iec 1000-4-2 model, and figure 4b shows the current waveform for the ?kv iec 1000-4-2 level 4 esd contact discharge test. charge-current limit resistor discharge resistance storagecapacitor c s 100pf r c 1m r d 1500 high- voltage dc source device under test figure 3a. human body esd test model i p 100% 90% 36.8% t rl time t dl current waveform peak-to-peak ringing(not drawn to scale) i r 10% 0 0 amperes figure 3b. human body current waveform downloaded from: http:///
the air-gap test involves approaching the device with acharged probe. the contact discharge method connects the probe to the device before the probe is energized. machine model the machine model for esd tests all pins using a200pf storage capacitor and zero discharge resis- tance. its objective is to emulate the stress caused by contact that occurs with handling and assembly during manufacturing. all pins require this protection during manufacturing, not just rs-232 inputs and outputs. therefore, after pc board assembly, the machine model is less relevant to i/o ports. __________applications information capacitor selection the capacitor type used for c1 c4 is not critical for proper operation; polarized or nonpolarized capacitorscan be used. the charge pump requires 0.1? capacitors for 2.5v operation (table 2). do not use values smaller than those listed in table 2. increasing the capacitor values (e.g., by a factor of 2) reduces ripple on the transmitter outputs and slightly reduces power con- sumption. c2, c3, and c4 can be increased without changing c1 s value. however, do not increase c1 without also increasing the values of c2, c3, and c4 tomaintain the proper ratios (c1 to the other capacitors). when using the minimum required capacitor values, make sure the capacitor value does not degrade excessively with temperature. if in doubt, use capacitors with a larger nominal value. the capacitor s equivalent series resistance (esr), which usually rises at low tem-peratures, influences the amount of ripple on v+ and v-. power-supply decoupling in most circumstances, a 0.1? bypass capacitor is adequate. in applications that are sensitive to power- supply noise, decouple v cc to ground with a capacitor of the same value as charge-pump capacitor c1. connectbypass capacitors as close to the ic as possible. transmitter outputs when exiting shutdown figure 2 shows two transmitter outputs when exitingshutdown mode. as they become active, the two transmitter outputs are shown going to opposite rs-232 levels (one transmitter input is high; the other is low). each transmitter is loaded with 3k in parallel with 1000pf. the transmitter outputs display no ringing orundesirable transients as they come out of shutdown. note that the transmitters are enabled only when the magnitude of v- exceeds approximately 2.5v. max3388e/max3389e 2.5v, 15kv esd-protected rs-232 transceivers for pdas and cell phones 8 _______________________________________________________________________________________ charge-current limit resistor discharge resistance storagecapacitor c s 150pf r c 50m to 100m r d 330 high- voltage dc source device under test figure 4a. iec 1000-4-2 esd test model t r = 0.7ns to 1ns 30ns 60ns t 100% 90%10% i peak i figure 4b. iec 1000-4-2 esd generator current waveform table 2. minimum required capacitorvalues v cc (v) c1?4 (?) 2.5 to 3.0 0.1 downloaded from: http:///
max3388e/max3389e 2.5v, 15kv esd-protected rs-232 transceivers for pdas and cell phones high data rates the max3388e/max3389e maintain rs-232-compatibletransmitter output voltages even at high data rates. figure 5 shows a transmitter loopback test circuit. figure 6 shows a loopback test result at 250kbps, and figure 7 shows the same test at 460kbps. for figure 6, all transmitters were driven simultaneously at 250kbps into rs-232 loads in parallel with 1000pf. for figure 7, a single transmitter was driven at 460kbps, and all transmitters were loaded with an rs-232 receiver in parallel with 150pf. power switch the max3388e/max3389e contain an internal switchfor powering external circuitry. this can be used to power hot-sync circuitry or other low-power circuitry. the switch on- resistance is typically 62 . the swin side of the switch is esd protected to ?5kv. logic-level i/o in addition to the traditional rs-232 i/o, themax3388e/max3389e have a logic-level transceiver from the rs-232 connector side to the cmos-logic side. the input impedance is typically 30k , and the output is open drain. the logic level i/o is active duringshutdown for the max3389e. this i/o transceiver is useful for hot syncing or other dedicated communication capability. the input is esd protected to ?5kv. typical pda/cell-phone application the max3388e/max3389e designed with pda applica- tions in mind. two transmitters and two receivers handlestandard full-duplex communication protocol, while an extra transmitter allows a ring indicator (ri) signal to alert the uart on the pc. without the ring indicator transmit- ter, solutions for these applications would require soft- ware-intensive polling of the cradle inputs. the ri signal is generated when a pda, cellular phone, or other cradled device is plugged into its cradle. this generates a logic-low signal to ri transmitter input, creat-ing +3.7v at the ring indicate pin. the pc s uart ri input is the only pin that can generate an interrupt from signalsarriving through the rs-232 port. the interrupt routine for this uart will then service the rs-232 full-duplex com- munication between the pda and the pc. as cell phone design becomes more like that of pdas, cell phones will require similar docking ability and com- munication protocol. cell phones operate on a single lithium-ion (li+) battery and generate a regulated out- put voltage of +2.35v to +3v from the phone connector. the baseband logic coming from the phone connector can be as low as 1.8v at the transceivers. to prevent forward biasing of a device internal to the cell phone, the max3388e/max3389e come with a logic power- supply pin (v l ) that limits the logic levels presented to max3388emax3389e 5k r_ in r_ out c2- c2+ c1- c1+ v- v+ v cc c4 c3 c1 c2 0.1 f v cc shdn t_ out t_ in gnd v cc c l figure 5. loopback test circuit 1 s/div t1in t1out 2v/div5v/div r1out 5v/div c l = 1000pf figure 6. loopback test results at 250kbps _______________________________________________________________________________________ 9 downloaded from: http:///
the phone. the receiver outputs will sink to zero for lowoutputs, but will not exceed v l for logic highs. the input logic levels for the transmitters are also altered,scaled by the magnitude of the v l input. the devices will work with v l as low as 1.8v. this is useful with cell phones and other power-efficient devices with corelogic voltage levels that go as low as 1.8v. chip information transistor count: 1323 max3388e/max3389e 2.5v, 15kv esd-protected rs-232 transceivers for pdas and cell phones 10 ______________________________________________________________________________________ 1 s/div t1in t1out 2v/div5v/div r1out 5v/div c l = 150pf figure 7. loopback test results at 460kbps downloaded from: http:///
max3388e/max3389e 2.5v, 15kv esd-protected rs-232 transceivers for pdas and cell phones package information tssop.eps 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 _____________________ 11 2001 maxim integrated products printed usa is a registered trademark of maxim integrated products. downloaded from: http:///

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