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for free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800. for small orders, phone 408-737-7600 ext. 3468. ________________general description the max3224?ax3227/max3244/max3245 are 3v- powered eia/tia-232 and v.28/v.24 communications interfaces with automatic shutdown/wakeup features and high data-rate capabilities. all devices achieve a 1? supply current using maxim? revolutionary autoshutdown plus feature. these devices automatically enter a low-power shutdown mode when the rs-232 cable is disconnected or the transmitters of the connected peripherals are inactive, and the uart driving the transmitter inputs is inactive for more than 30 seconds. they turn on again when they sense a valid transition at any transmitter or receiv- er input. autoshutdown plus saves power without changes to the existing bios or operating system. the max3225/max3227/max3245 also feature megabaud operation, guaranteeing 1mbps for high- speed applications such as communicating with isdn modems. the max3224/max3226/max3244 guarantee 250kbps operation. the transceivers have a proprietary low-dropout transmitter output stage enabling true rs- 232 performance from a +3.0v to +5.5v supply with a dual charge pump. the charge pump requires only four small 0.1? capacitors for operation from a 3.3v supply. the max3224?ax3227 feature a logic-level output (ready) that asserts when the charge pump is regulat- ing and the device is ready to begin transmitting. all devices are available in a space-saving ssop pack- age. ________________________applications notebook, subnotebook, and palmtop computers cellular phones battery-powered equipment hand-held equipment peripherals printers ____________________________features ? 1? supply current ? autoshutdown plus?dn innovation of the year ? guaranteed data rate: 250kbps (max3224/3226/3244) 1mbps (max3225/3227/3245) ? guaranteed slew rate: 6v/? (max3224/3226/3244) 24v/? (max3225/3227/3245) ? meets eia/tia-232 specifications down to 3.0v ? guaranteed mouse driveability (max3244/3245) ? ready-to-transmit logic-level output max3224?ax3227/max3244/max3245 ? 1? supply current, 1mbps, 3.0v to 5.5v, rs-232 transceivers with autoshutdown plus ________________________________________________________________ maxim integrated products 1 19-1289; rev 1; 3/98 part max3224 max3225 max3226 1/1 2/2 2/2 no. of drivers/ receivers ready output 4 4 4 auto- shutdown plus 4 4 4 250k 1m 250k guaranteed data rate (bps) max3227 max3244 max3245 3/5 3/5 1/1 4 4 4 4 1m 250k 1m part max3224 cpp max3224cap max3224epp -40? to +85? 0? to +70? 0? to +70? temp. range pin-package 20 plastic dip 20 ssop 20 plastic dip MAX3224EAP max3225 cpp max3225cap 0? to +70? 0? to +70? -40? to +85? 20 ssop 20 plastic dip 20 ssop max3225epp -40? to +85? 20 plastic dip max3225eap -40? to +85? 20 ssop ordering information continued at end of data sheet. autoshutdownplus and megabaud are trademarks of maxim integrated products. ? covered by u.s. patent numbers 4,636,930; 4,679,134; 4,777,577; 4,797,899; 4,809,152; 4,897,774; 4,999,761; 5,649,210; and othe r patents pending. _____________________ selector guide _______________ordering information
max3224?ax3227/max3244/max3245 1 a supply cur r ent, 1mbps, 3.0v to 5.5v , rs-232 t ransceivers with autoshutdown plus 2 _______________________________________________________________________________________ absolute maximum ratings electrical characteristics (v cc = +3v to +5.5v, c1?4 = 0.1 f, tested at 3.3v 10%; c l = 0.047 f, c2?4 = 0.33 f, tested at 5.0v 10%; t a = t min to t max , unless otherwise noted. typical values are at t a = +25 c.) stresses beyond those listed under ?bsolute maximum ratings?may cause permanent damage to the device. these are stress rating s only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specificatio ns is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. v cc to gnd .............................................................. -0.3v to +6v v+ to gnd (note 1) .................................................. -0.3v to +7v v- to gnd (note 1) ................................................... +0.3v to -7v v+ + ? v - ? (note 1) ................................................................ +13v input voltages t_in, forceon, forceoff to gnd ................ -0.3v to +6v r_in to gnd .................................................................... 25v output voltages t_out to gnd ............................................................. 13.2v r_out, invalid , ready to gnd ......... -0.3v to (v cc + 0.3v) short-circuit duration t_out to gnd ....................................................... continuous continuous power dissipation (t a = +70 c) 16-pin ssop (derate 7.14mw/ c above +70 c) ......... 571mw 20- p in plastic dip (derate 11.11mw/ c above +70 c) ... 889mw 20 - pin ssop (derate 8.00mw/ c above +70 c) ......... 640mw 28 - pin wide so (derate 12.5mw/ c above +70 c) ........... 1w 28 - pin ssop (derate 9.52mw/ c above +70 c) ......... 762mw operating temperature ranges max32_ _c_ _ .................................................... 0 c to +70 c max32_ _e_ _ .................................................. -40 c to +85 c storage temperature range ............................. -65 c to +160 c lead temperature (soldering, 10sec) ............................. +300 c note 1: v+ and v- can have maximum magnitudes of 7v, but their absolute difference cannot exceed 13v. v cc = 5.0v forceon = gnd, forceoff = v cc , all r_in idle, all t_in idle t a = +25 c v cc = 3.3v t_in, forceon, forceoff conditions k 3 5 7 input resistance v 0.5 input hysteresis 1.8 2.4 v 1.5 2.4 input threshold high 0.8 1.5 v 0.6 1.2 input threshold low v -25 +25 input voltage range v v cc - 0.6 v cc - 0.1 output voltage high v 0.4 output voltage low a 1 10 supply current, shutdown a 1 10 supply current, autoshutdown plus a 0.05 10 output leakage current a 0.01 1 transmitter input hysteresis v 0.5 v 2.4 input logic threshold high ma 0.3 1 supply current, autoshutdown plus disabled v 0.8 input logic threshold low 2 units min typ max symbol parameter forceoff = gnd t a = +25 c v cc = 5.0v v cc = 3.3v t a = +25 c r_out (max3244/max3245), receivers disabled t_in, forceon, forceoff v cc = 5.0v forceon = forceoff = v cc , no load t_in, forceon, forceoff i out = -1.0ma v cc = 3.3v i out = 1.6ma dc characteristics (v cc = 3.3v or 5.0v, t a = +25 c) logic inputs and receiver outputs receiver inputs input leakage current
max3224?ax3227/max3244/max3245 1 a supply cur r ent, 1mbps, 3.0v to 5.5v , rs-232 t ransceivers with autoshutdown plus _______________________________________________________________________________________ 3 electrical characteristics (continued) (v cc = +3v to +5.5v, c1?4 = 0.1 f, tested at 3.3v 10%; c l = 0.047 f, c2?4 = 0.33 f, tested at 5.0v 10%; t a = t min to t max , unless otherwise noted. typical values are at t a = +25 c.) conditions 300 10m output resistance v 5 5.4 output voltage swing units min typ max symbol parameter figure 4a t1in = t2in = gnd, t3in = v cc , t3out loaded with 3k to gnd, t1out and t2out loaded with 2.5ma each sec 15 30 60 t autoshdn receiver or transmitter edge to transmitters shutdown s 100 t wu receiver or transmitter edge to transmitters enabled s 30 t invl receiver positive or negative threshold to invalid low s 1 t invh receiver positive or negative threshold to invalid high v v cc - 0.6 invalid , ready (max3224?ax3227) output voltage high v 0.4 invalid , ready (max3224?ax3227) output voltage low v -0.3 0.3 receiver input threshold to invalid output low -2.7 v 2.7 receiver input threshold to invalid output high v 5 transmitter output voltage a 25 output leakage current 60 ma output short-circuit current v cc = v+ = v- = 0, transmitter outputs = 2v all transmitter outputs loaded with 3k to ground v cc = 5v, figure 5b (note 2) v cc = 5v, figure 5b (note 2) v cc = 5v, figure 4b v cc = 5v, figure 4b i out = -1.0ma i out = -1.6ma figure 4a negative threshold positive threshold v cc = 0 or 3v to 5.5v, v out = 12v, transmitters disabled transmitter outputs mouse driveability (max3244/max3245) autoshutdown plus (forceon = gnd, forceoff = v cc )
max3224?ax3227/max3244/max3245 1 a supply cur r ent, 1mbps, 3.0v to 5.5v , rs-232 t ransceivers with autoshutdown plus 4 _______________________________________________________________________________________ timing characteristics?ax3224/max3226/max3244 (v cc = +3v to +5.5v, c1?4 = 0.1 f, tested at 3.3v 10%; c l = 0.047 f, c2?4 = 0.33 f, tested at 5.0v 10%; t a = t min to t max , unless otherwise noted. typical values are at t a = +25 c.) timing characteristics?ax3225/max3227/max3245 (v cc = +3v to +5.5v, c1?4 = 0.1 f, tested at 3.3v 10%; c l = 0.047 f, c2?4 = 0.33 f, tested at 5.0v 10%; t a = t min to t max , unless otherwise noted. typical values are at t a = +25 c.) note 2: a transmitter/receiver edge is defined as a transition through the transmitter/receiver input logic thresholds. note 3: transmitter skew is measured at the transmitter zero cross points. c l = 150pf to 2500pf c l = 150pf to 1000pf r_in to r_out, c l = 150pf r l = 3k , c l = 1000pf, one transmitter switching v cc = 3.3v, t a = +25 c, r l = 3k to 7k , measured from +3v to -3v or -3v to +3v normal operation (max3244 only) normal operation (max3244 only) (note 3) conditions 0.15 t plh s 0.15 t phl kbps 250 maximum data rate receiver propagation delay v/ s 4 30 6 30 transition-region slew rate ns 200 receiver output enable time ns 200 receiver output disable time ns 100 ? t phl - t plh ? transmitter skew ns 50 ? t phl - t plh ? receiver skew units min typ max symbol parameter v cc = 4.5v to 5.5v, r l = 3k , c l = 1000pf, one transmitter switching v cc = 3.0v to 4.5v, r l = 3k , c l = 250pf, one transmitter switching r l = 3k , c l = 1000pf, one transmitter switching v cc = 3.3v, t a = +25 c, r l = 3k to 7k , c l = 150pf to 1000pf, measured from +3v to -3v or -3v to +3v (note 3) r_in to r_out, c l = 150pf normal operation (max3245 only) normal operation (max3245 only) conditions 1000 1000 kbps 250 maximum data rate v/ s 24 150 transition-region slew rate ns 50 ? t phl - t plh ? receiver skew ns 25 ? t phl - t plh ? transmitter skew s 0.15 t phl receiver propagation delay 0.15 t plh ns 200 receiver output enable time ns 200 receiver output disable time units min typ max symbol parameter
max3224?ax3227/max3244/max3245 1 a supply cur r ent, 1mbps, 3.0v to 5.5v , rs-232 t ransceivers with autoshutdown plus _______________________________________________________________________________________ 5 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 0 1000 2000 3000 4000 5000 max3224/max3226 transmitter output voltage vs. load capacitance max3224-01 load capacitance (pf) transmitter output voltage (v) t1 transmitting at 250kbps t2 (max3224) transmitting at 15.6kbps v out+ v out- 0 2 4 6 8 10 12 14 16 0 1000 2000 3000 4000 5000 max3224/max3226 slew rate vs. load capacitance max3224-02 load capacitance (pf) slew rate (v/ m s) -slew +slew for data rates up to 250kbps 0 5 10 15 20 25 30 35 40 45 0 2000 1000 3000 4000 5000 max3224/max3226 operating supply current vs. load capacitance max3224-03 load capacitance (pf) supply current (ma) 250kbps 120kbps 20kbps t1 transmitting at 250kbps t2 (max3224) transmitting at 15.6kbps -7.5 0 -2.5 -5.0 2.5 5.0 7.5 0 1000 500 1500 2000 2500 max3225/max3227 transmitter output voltage vs. load capacitance max3224-04 load capacitance (pf) transmitter output voltage (v) 2mbps 2mbps 1.5mbps 1.5mbps 1mbps 1mbps 1 transmitter at full data rate 1 transmitter at 1/16 data rate (max3225) load = 3k w + c l 0 15 10 5 20 25 30 35 40 45 50 0 1000 500 1500 2000 2500 3000 max3225/max3227 transmitter skew vs. load capacitance max3224-07 load capacitance (pf) transmitter skew (ns) average; 10 parts 1 transmitter at 512kbps 1 transmitter at 30kbps (max3225) load = 3k w + c l 0 80 70 60 50 40 30 20 10 0 500 1000 1500 2000 2500 max3225/max3227 slew rate vs. load capacitance max3224-05 load capacitance (pf) slew rate (v/ m s) 1 transmitter at 1mbps 1 transmitter at 62.5kbps (max3225) -slew +slew 0 20 10 40 30 60 50 70 90 80 100 0 500 1000 1500 2000 2500 max3225/max3227 operating supply current vs. load capacitance max3224-06 load capacitance (pf) supply current (ma) 2mbps 1.5mbps 1mbps 1 transmitter at full data rate 1 transmitter at 1/16 data rate (max3225) load = 3k w + c l 20 24 22 30 28 26 36 34 32 38 -40 0 20 -20 40 60 80 100 max3224?ax3227 ready turn-on time vs. temperature max3224-08 temperature (?) ready turn-on time ( m s) 0 200 180 160 140 120 100 80 60 40 20 -40 0 20 -20 40 60 80 100 max3224?ax3227 ready turn-off time vs. temperature max3224-09 temperature (?) ready turn-off time (ns) __________________________________________ t ypical operating characteristics (v cc = +3.3v, 250kbps data rate, c1?4 = 0.1 f, all transmitters loaded with 3k and c l , t a = +25 c, unless otherwise noted.)
max3224?ax3227/max3244/max3245 1 a supply cur r ent, 1mbps, 3.0v to 5.5v , rs-232 t ransceivers with autoshutdown plus 6 _______________________________________________________________________________________ t ypical operating characteristics (continued) (v cc = +3.3v, 250kbps data rate, c1?4 = 0.1 f, all transmitters loaded with 3k and c l , t a = +25 c, unless otherwise noted.) -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 0 1000 2000 3000 4000 5000 max3244 transmitter output voltage vs. load capacitance max3224-10 load capacitance (pf) transmitter output voltage (v) 1 transmitter at 250kbps 2 transmitters at 15.6kbps v out+ v out- 0 4 2 8 6 12 10 14 0 1000 2000 3000 4000 5000 max3244 slew rate vs. load capacitance max3224-11 load capacitance (pf) slew rate (v/ m s) 0 30 20 10 40 50 60 0 2000 1000 3000 4000 5000 max3244 operating supply current vs. load capacitance max3224-12 load capacitance (pf) supply current (ma) 250kbps 120kbps 20kbps 1 transmitter at 250kbps 2 transmitters at 15.6kbps -7.5 0 -2.5 -5.0 2.5 5.0 7.5 0 800 400 1200 1600 2000 max3245 transmitter output voltage vs. load capacitance max3224-13 load capacitance (pf) transmitter output voltage (v) 2mbps 2mbps 1.5mbps 1.5mbps 1mbps 1mbps 1 transmitter at full data rate 2 transmitters at 1/16 data rate 0 20 10 40 30 60 50 70 90 80 100 0 400 800 1200 1600 2000 max3245 operating supply current vs. load capacitance max3224-15 load capacitance (pf) supply current (ma) 2mbps 1.5mbps 1mbps 1 transmitter at full data rate 2 transmitters at 1/16 data rate 0 20 10 40 30 60 50 70 0 400 800 1200 1600 2000 max3245 slew rate vs. load capacitance max3224-14 load capacitance (pf) slew rate (v/ m s) 1 transmitter at 1mbps 2 transmitters at 62.5kbps 0 15 10 5 20 25 30 35 40 45 50 0 1000 2000 3000 max3245 transmitter skew vs. load capacitance max3224-16 load capacitance (pf) transmitter skew (ns)
_______________ detailed description dual charge-pump voltage converter the max3224?ax3227/max3244/max3245? internal power supply consists of a regulated dual charge pump that provides output voltages of +5.5v (doubling charge pump) and -5.5v (inverting charge pump), over the +3.0v to +5.5v range. the charge pump operates in discontinuous mode: if the output voltages are less than 5.5v, the charge pump is enabled; if the output voltages exceed 5.5v, the charge-pump is disabled. each charge pump requires a flying capacitor (c1, c2) and a reservoir capacitor (c3, c4) to generate the v+ and v- supplies. the ready output (max3224?ax3227) is low when the charge pumps are disabled in shutdown mode. the ready signal asserts high when v- goes below -4v. rs-232 transmitters the transmitters are inverting level translators that convert cmos-logic levels to 5.0v eia/tia-232 levels. the max3224/max3226/max3244 guarantee a 250kbps data rate (1mbps for the max3225/max3227/ max3245) with worst-case loads of 3k in parallel with 1000pf, providing compatibility with pc-to-pc com- munication software (such as laplink). transmitters can be paralleled to drive multiple receivers. figure 1 shows a complete system connection. max3224?ax3227/max3244/max3245 1 a supply cur r ent, 1mbps, 3.0v to 5.5v , rs-232 t ransceivers with autoshutdown plus _______________________________________________________________________________________ 7 pin name max3224 max3225 max3226 max3227 max3244 max3245 1 1 ready 2 2 28 c1+ positive terminal of voltage-doubler charge-pump capacitor 3 3 27 v+ +5.5v generated by the charge pump 4 4 24 c1- negative terminal of voltage-doubler charge-pump capacitor 5 5 1 c2+ positive terminal of inverting charge-pump capacitor 6 6 2 c2- negative terminal of inverting charge-pump capacitor 7 7 3 v- -5.5v generated by the charge pump 8, 17 13 9?1 t_out rs-232 transmitter outputs 9, 16 8 4? r_in rs-232 receiver inputs 10, 15 9 15?9 r_out ttl/cmos receiver outputs 11 10 21 invalid valid signal detector output, active low. a logic high indicates that a valid rs-232 level is present on a receiver input. 12, 13 11 12?4 t_in ttl/cmos transmitter inputs 14 12 23 forceon force-on input, active high. drive high to override autoshutdown plus, keeping transmitters and receivers on ( forceoff must be high) (table 1). 18 14 25 gnd ground 19 15 26 v cc +3.0v to +5.5v single supply voltage 20 16 22 forceoff force-off input, active low. drive low to shut down transmitters, receivers (except r2outb), and charge pump. this overrides autoshutdown plus and forceon (table 1). 20 r2outb ttl/cmos noninverting complementary receiver outputs. always active. ready to transmit output, active high. ready is enabled high when v- goes below -4v and the device is ready to transmit. function pin description laplink is a trademark of traveling software.
max3224?ax3227/max3244/max3245 when forceoff is driven to ground or when the auto- shutdown plus circuitry senses that all receiver and transmitter inputs are inactive for more than 30sec, the transmitters are disabled and the outputs go into a high- impedance state. when powered off or shut down, the outputs can be driven to 12v. the transmitter inputs do not have pull-up resistors. connect unused inputs to gnd or v cc . rs-232 receivers the receivers convert rs-232 signals to cmos-logic output levels. the max3224?ax3227 feature inverting outputs that always remain active (table 1). the max3244/max3245 have inverting three-state outputs that are high impedance when shut down ( forceoff = gnd) (table 1). 1 a supply cur r ent, 1mbps, 3.0v to 5.5v , rs-232 t ransceivers with autoshutdown plus 8 _______________________________________________________________________________________ max3244 max3245 i/o chip with uart cpu rs-232 power- management unit or keyboard controller forceoff forceon invalid figure 1. interface under control of pmu max3244 max3245 t1out r2outb tx 5k uart v cc t1in three-stated logic transition detector r2in protection diode r2out forceoff = gnd v cc to m p rx previous rs-232 tx uart shdn = gnd v cc v cc gnd rx 5k a) older rs-232: powered-down uart draws current from active receiver output in shutdown. b) new max3244/max3245: in shutdown, r2outb is used to monitor external devices and r2out is three stated, eliminating a current path through the uart? protection diode. gnd protection diode i i figure 2. the max3244/max3245 detect rs-232 activity when the uart and interface are shut down.
the max3244/max3245 feature an extra, always active, noninverting output, r2outb. r2outb output monitors receiver activity while the other receivers are high impedance, allowing ring indicator applications to be monitored without forward biasing other devices connected to the receiver outputs. this is ideal for sys - tems where v cc is set to ground in shutdown to accommodate peripherals such as uarts (figure 2). the max3224?ax3227/max3244/max3245 feature an invalid output that is enabled low when no valid rs-232 voltage levels have been detected on all receiver inputs. because invalid indicates the receiv - er input? condition, it is independent of forceon and forceoff states (figures 3 and 4). autoshutdown plus mode the max3224?ax3227/max3244/max3245 achieve a 1 a suppl y current with maxim? autoshutdown plusfeature, which operates when forceoff is high and a forceon is low. when these devices do not sense a valid signal transition on any receiver and trans - mitter input for 30sec, the on-board charge pumps are shut down, reducing supply current to 1 a. this occurs if the rs-232 cable is disconnected or if the connected peripheral transmitters are turned off, and the uart dri - ving the transmitter inputs is inactive. the system turns on again when a valid transition is applied to any rs-232 receiver or transmitter input. as a result, the sys - tem saves power without changes to the existing bios or operating system. max3224?ax3227/max3244/max3245 1 a supply cur r ent, 1mbps, 3.0v to 5.5v , rs-232 t ransceivers with autoshutdown plus _______________________________________________________________________________________ 9 table 1. output control truth table operation status forceon forceoff valid receiver level receiver or transmitter edge within 30sec t_out r_out (max3224/ max3225/ max3226/ max3227) r_out (max3244/ max3245) r2outb (max3244/ max3245) shutdown (forced off) x 0 x x high-z active high-z active normal operation (forced on) 1 1 x x active active active active normal operation (autoshutdown plus) 0 1 x yes active active active active shutdown (auto- shutdown plus) 0 1 x no high-z active active active normal operation invalid * 1 yes x active active active active normal operation invalid * 1 x yes active active active active shutdown invalid * 1 no no high-z active active active normal operation (autoshutdown) invalid * invalid ** yes x active active active active shutdown (autoshutdown) invalid * invalid ** no x high-z active high-z active x = don? care * invalid connected to forceon ** invalid connected to forceon and forceoff
max3224?ax3227/max3244/max3245 figures 3a and 3b depict valid and invalid rs-232 receiver voltage levels. invalid indicates the receiver input? condition, and is independent of forceon and forceoff states. figure 3 and tables 1 and 2 sum - marize the operating modes of the max3224 max3227/max3244/max3245 devices. forceon and forceoff override autoshutdown plus circuitry. when neither control is asserted, the ic selects between these states automatically based on the last receiver or transmitter input edge received. when shut down, the device? charge pumps turn off, v+ is pulled to v cc , v- is pulled to ground, the transmit - ter outputs are high impedance, and ready (max3224?ax3227) is driven low. the time required to exit shutdown is typically 100 s (figure 8). by connecting forceon to invalid , the max3224 max3227/max3244/max3245 shut down when no valid receiver level and no receiver or transmitter edge is detected for 30sec, and wake up when a valid receiver level or receiver or transmitter edge is detected. by connecting forceon and forceoff to invalid , the max3224 max3227/max3244/max3245 shutdown when no valid receiver level is detected and wake up 1 a supply cur r ent, 1mbps, 3.0v to 5.5v , rs-232 t ransceivers with autoshutdown plus 10 ______________________________________________________________________________________ +0.3v -0.3v invalid r_in invalid asserted if all receiver inputs are between +0.3v and -0.3v for at least 30 m s. 30? timer r +2.7v -2.7v invalid r_in invalid deasserted if any receiver input has been between +2.7v and -2.7v for less than 30 m s. 30? timer r autoshdn r_in t_in r s 30sec timer edge detect edge detect forceoff forceon figure 3a. invalid functional diagram, invalid low figure 3b. invalid functional diagram, invalid high figure 3c. autoshutdown plus logic powerdown* autoshdn forceoff forceon * powerdown is only an internal signal. it controls the operational status of the transmitters and the power supplies. figure 3d. power-down logic receiver input levels -2.7v -0.3v +2.7v +0.3v 0 indeterminate invalid high invalid low invalid high indeterminate figure 4a. receiver positive/negative thresholds for invalid rs-232 signal present at any receiver input invalid output yes high no low table 2. invalid truth table
when a valid receiver level is detected (same function - ality as autoshutdown feature on max3221/max3223/ max3243). a mouse or other system with autoshutdown plus may need time to wake up. figure 5 shows a circuit that forces the transmitters on for 100ms, allowing enough time for the other system to realize that the max3244/ max3245 is awake. if the other system outputs valid rs-232 signal transitions within that time, the rs-232 ports on both systems remain enabled. software-controlled shutdown if direct software control is desired, use invalid to indicate dtr or ring indicator signal. tie forceoff and forceon together to bypass the autoshutdown plus so the line acts like a shdn input. max3224?ax3227/max3244/max3245 1 a supply cur r ent, 1mbps, 3.0v to 5.5v , rs-232 t ransceivers with autoshutdown plus ______________________________________________________________________________________ 11 v cc 0 0 v+ v- v cc 0 invalid output output transmitter inputs receiver inputs } invalid region *max3224?ax3227 transmitter outputs *v cc t autoshdn t wu t wu t invl t invh t autoshdn figure 4b. autoshutdown plus, invalid, and ready timing diagram forceon master shdn line 0.1 m f 1m forceoff max3224 max3225 max3226 max3227 max3244 max3245 power- management unit figure 5. autoshutdown plus initial turn-on to wake up a mouse or another system
table 3. required minimum capacitance values max3224?ax3227/max3244/max3245 __________ applications infor mation capacitor selection the capacitor type used for c1?4 is not critical for proper operation; polarized or nonpolarized capacitors can be used. the charge pump requires 0.1 f capaci - tors for 3.3v operation. for other supply voltages, see table 3 for required capacitor values. do not use val - ues smaller than those listed in table 3. increasing the capacitor values (e.g., by a factor of 2) reduces ripple on the transmitter outputs and slightly reduces power consumption. c2, c3, and c4 can be increased without changing c1? value. however, do not increase c1 without also increasing the values of c2, c3, c4, and c bypass , to maintain 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 capaci - tors with a larger nominal value. the capacitor? equiv - alent series resistance (esr), which usually rises at low temperatures, influences the amount of ripple on v+ and v-. power-supply decoupling in most circumstances, a 0.1 f v cc bypass capacitor is adequate. in applications that are sensitive to power- supply noise, use a capacitor of the same value as charge-pump capacitor c1. connect bypass capaci - tors as close to the ic as possible. transmitter outputs when exiting shutdown figure 6 shows two transmitter outputs when exiting shutdown mode. as they become active, the two trans - mitter outputs are shown going to opposite rs-232 lev - els (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 or undesir - able transients as they come out of shutdown. note that the transmitters are enabled only when the magnitude of v- exceeds approximately -3v. high data rates the max3224/max3226/max3244 maintain the rs-232 5.0v minimum transmitter output voltage even at high data rates. figure 7 shows a transmitter loopback test circuit. figure 8 shows a loopback test result at 120kbps, and figure 9 shows the same test at 250kbps. for figure 8, all transmitters were driven 1 a supply cur r ent, 1mbps, 3.0v to 5.5v , rs-232 t ransceivers with autoshutdown plus 12 ______________________________________________________________________________________ v cc (v) c2, c3, c4 ( f) 3.0 to 3.6 0.1 c1, c bypass ( f) 0.1 4.5 to 5.5 0.33 3.0 to 5.5 1 0.047 0.22 5 m s/div t1out forceon = forceoff t2out ready 5v/div 0 2v/div 0 5v/div 0 v cc = 3.3v c1?4 = 0.1 m f figure 6. transmitter outputs when exiting shutdown or powering up max3224 max3225 max3226 max3227 max3244 max3245 5k r_ in r_ out forceon c2- c2+ c1- c1+ v- v+ v cc c4 c3* c1 c2 c bypass v cc forceoff *c3 can be returned to v cc or gnd. t_ out t_ in gnd v cc 1000pf figure 7. loopback test circuit
simultaneously at 120kbps into rs-232 loads in parallel with 1000pf. for figure 9, a single transmitter was dri - ven at 250kbps, and all transmitters were loaded with an rs-232 receiver in parallel with 250pf. the max3225/max3227/max3245 maintain the rs-232 5.0v minimum transmitter output voltage at data rates up to 1mbps (megabaud). figure 10 shows a loopback test result with a single transmitter driven at 1mbps and all transmitters loaded with an rs-232 receiver in paral - lel with 250pf. mouse driveability the max3244/max3245 are specifically designed to power serial mice while operating from low-voltage power supplies. they have been tested with leading mouse brands from manufacturers such as microsoft and logitech. the max3244/max3245 successfully drove all serial mice tested and met their respective current and voltage requirements. the max3244/ max3245 dual charge pump ensures the transmitters will supply at least 5v during worst-case conditions. figure 11a shows the transmitter output voltages under increasing load current. figure 11b shows a typical mouse connection. max3224?ax3227/max3244/max3245 1 a supply cur r ent, 1mbps, 3.0v to 5.5v , rs-232 t ransceivers with autoshutdown plus ______________________________________________________________________________________ 13 figure 8. max3224/max3226/max3244 loopback test result at 120kbps 2 m s/div t1in t1out r1out 5v/div 5v/div 5v/div v cc = 3.3v figure 9. max3224/max3226/max3244 loopback test result at 250kbps 2 m s/div t1in t1out r1out 5v/div 5v/div 5v/div v cc = 3.3v figure 10. max3225/max3227/max3245 loopback test result at 1mbps 200ns/div t1in t1out r1out 5v/div 5v/div 5v/div v cc = 3.3v -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 0 1 2 3 4 5 6 7 8 9 10 load current per transmitter (ma) transmitter output voltage (v) v out+ v out- v out+ v out- v cc v cc = 3.0v figure 11a. max324_ transmitter output voltage vs. load current per transmitter
max3224?ax3227/max3244/max3245 1 a supply cur r ent, 1mbps, 3.0v to 5.5v , rs-232 t ransceivers with autoshutdown plus 14 ______________________________________________________________________________________ figure 11b. mouse driver test circuit +v computer serial port +v -v gnd tx serial mouse max3244 max3245 forceoff 23 r5out 15 r4out 16 r3out 17 r2out 18 r1out 19 r2outb 20 logic outputs 5k 5k 5k 5k 5k r5in 8 r4in 7 r3in 6 r2in 5 r1in 4 rs-232 inputs gnd 25 logic inputs t3in 12 t2in 13 t1in 14 c2- 2 c2+ 1 c1- 24 c1+ 28 t3out 11 t2out 10 t1out 9 v- 3 v+ 27 v cc v cc c4 0.1 m f c3 0.1 m f 0.1 m f 26 c1 0.1 m f c2 0.1 m f forceon invalid 22 21 to power- management unit +3.3v
interconnection with 3v and 5v logic the max3224?ax3227/max3244/max3245 can directly interface with various 5v logic families, includ - ing act and hct cmos. see table 4 for more infor - mation on possible combinations of interconnections. table 5 lists other maxim 3.0v to 5.5v powered trans - ceivers. max3224?ax3227/max3244/max3245 1 a supply cur r ent, 1mbps, 3.0v to 5.5v , rs-232 t ransceivers with autoshutdown plus ______________________________________________________________________________________ 15 table 4. logic family compatibility with various supply voltages system power-supply voltage (v) compatibility 3.3 compatible with all cmos families 5 compatible with all ttl and cmos families v cc supply voltage (v) 3.3 5 5 compatible with act and hct cmos, and with ac, hc, or cd4000 cmos 3.3 table 5. 3.0v to 5.5v powered rs-232 transceivers from maxim p art supply voltage range (v) no. of tx/rx guaranteed data rate (bps) supply current ( a) max3241 +3.0 to +5.5 3/5 120k 300 max3243 +3.0 to +5.5 3/5 120k 1 max3244 +3.0 to +5.5 3/5 250k 1 max3245 +3.0 to +5.5 3/5 1m 1 max3232 +3.0 to +5.5 2/2 120k 300 max3222 +3.0 to +5.5 2/2 120k 300 max3223 +3.0 to +5.5 2/2 120k 1 max3224 +3.0 to +5.5 2/2 250k 1 max3225 +3.0 to +5.5 2/2 1m 1 max3221 +3.0 to +5.5 1/1 120k 1 max3227 +3.0 to +5.5 1/1 1m 1 max3226 +3.0 to +5.5 1/1 250k 1 auto- shutdown plus yes yes yes yes yes yes auto- shutdown yes yes yes
max3224?ax3227/max3244/max3245 1 a supply cur r ent, 1mbps, 3.0v to 5.5v , rs-232 t ransceivers with autoshutdown plus 16 ______________________________________________________________________________________ max3244 max3245 forceon 23 r5out 15 r4out 16 r3out 17 r2out 18 r1out 19 r2outb 20 forceoff 22 r5in 8 r4in 7 r3in 6 r2in 5 r1in 4 gnd 25 t3in 12 t2in 13 t1in 14 c2- 2 c2+ 1 c1- 24 c1+ 28 t3out 11 t2out 10 t1out 9 v- 3 v+ 27 v cc c4 0.1 m f c3 0.1 m f c1 0.1 m f c bypass 0.1 m f c2 0.1 m f +3.3v 26 invalid 21 autoshutdown plus max3226 max3227 forceon ready 12 1 r1out 9 forceoff 16 invalid 10 gnd 14 t1in 11 c2- 6 c2+ 5 c1- 4 c1+ 2 r1in 8 t1out 13 v- 7 v+ 3 v cc v cc c4 0.1 m f c3 0.1 m f 0.1 m f 15 c1 0.1 m f c2 0.1 m f c bypass c bypass +3.3v to power- management unit 5k max3224 max3225 forceon ready 14 1 r2out 10 r1out 15 forceoff 20 invalid 11 r2in 9 gnd 18 rs-232 outputs ttl/cmos inputs t2in 12 t1in 13 c2- 6 c2+ 5 c1- 4 c1+ 2 r1in 16 t2out 8 t1out 17 v- 7 v+ 3 v cc v cc c4 0.1 m f c3 0.1 m f 0.1 m f 19 c1 0.1 m f c2 0.1 m f +3.3v rs-232 inputs to power- management unit ttl/cmos outputs 5k 5k 5k 5k 5k 5k 5k autoshutdown plus autoshutdown plus ___________________________________________________t ypical operating cir cuits
max3224?ax3227/max3244/max3245 1 a supply cur r ent, 1mbps, 3.0v to 5.5v , rs-232 t ransceivers with autoshutdown plus ______________________________________________________________________________________ 17 16 15 14 13 12 11 10 9 1 2 3 4 5 6 7 8 ready c1+ v+ c1- c2+ c2- v- r1in forceoff v cc gnd t1out forceon t1in invalid r1out max3226 max3227 ssop 28 27 26 25 24 23 22 21 20 19 18 17 16 15 1 2 3 4 5 6 7 8 9 10 11 12 13 14 c1+ v+ v cc gnd c1- forceon forceoff invalid r2outb r1out r2out r3out r4out r5out c2+ c2- v- r1in r2in r3in r4in r5in t1out t2out t3out t3in t2in t1in so/ssop max3244 max3245 20 19 18 17 16 15 14 13 1 2 3 4 5 6 7 8 forceoff v cc gnd t1out c1- v+ c1+ ready r1in r1out forceon t1in t2out v- c2- c2+ 12 11 9 10 t2in invalid r2out r2in dip/ssop max3224 max3225 __________________________________________________________ _ pin configurations ___________________ chip infor mation max3224 transistor count: 1129 max3225 transistor count: 1129 max3226 transistor count: 1129 max3227 transistor count: 1129 max3244/max3245 transistor count: 1335 __or dering infor mation (continued) part max3227 cae max3227eae -40 c to +85 c 0 c to +70 c 16 ssop 16 ssop temp. range pin-package max3226 cae max3226eae max3244 cwi 0 c to +70 c -40 c to +85 c 0 c to +70 c 16 ssop 16 ssop 28 wide so max3244cai max3244ewi max3244eai -40 c to +85 c -40 c to +85 c 0 c to +70 c 28 ssop 28 wide so 28 ssop max3245 cwi 0 c to +70 c 28 wide so max3245cai max3245ewi max3245eai -40 c to +85 c -40 c to +85 c 0 c to +70 c 28 ssop 28 wide so 28 ssop
max3224?ax3227/max3244/max3245 1 a supply cur r ent, 1mbps, 3.0v to 5.5v , rs-232 t ransceivers with autoshutdown plus 18 ______________________________________________________________________________________ ________________________________________________________ package infor mation ssop.eps
max3224?ax3227/max3244/max3245 1 a supply cur r ent, 1mbps, 3.0v to 5.5v , rs-232 t ransceivers with autoshutdown plus ______________________________________________________________________________________ 19 ___________________________________________ package infor mation (continued) soicw.eps
max3224?ax3227/max3244/max3245 1 a supply cur r ent, 1mbps, 3.0v to 5.5v , rs-232 t ransceivers with autoshutdown plus maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim product. no circu it patent licenses are implied. maxim reserves the right to change the circuitry and specifications without notice at any time. 20 ____________________ maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 1998 maxim integrated products printed usa is a registered trademark of maxim integrated products. ___________________________________________ package infor mation (continued) pdipn.eps

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