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1 ? fn8037.7 ISL4241E, isl4243e q fn packaged, 15kv esd protected, +2.7v to +5.5v, 10nanoamp, 250kbps, rs-232 transmitters/receivers intersil?s ISL4241E, isl4243e devices are 2.7v to 5.5v powered rs-232 transmitters/receivers which meet ela/tia-232 and v.28/v.24 specifications, even at vcc = 3.0v. additionally, they provide 15kv esd protection (iec61000-4-2 air gap and human body model) on transmitter outputs and receiver inputs (rs-232 pins). targeted applications are pdas, palmtops, and notebook and laptop computers where the low operational, and even lower standby, power consumpt ion is critical. efficient on-chip charge pumps, coupled with manual and automatic power-down functions, reduce the standby supply current to a 10na trickle. tiny 5mmx5m m quad flat no-lead (qfn) packaging and the use of small, low value capacitors ensure board space savings as well. data rates greater than 250kbps are guaranteed at worst case load conditions. the ISL4241E, isl4243e?s are 3 driver, 5 receiver devices that, coupled with the 5x 5 qfn package, provide the industry?s smallest, lowest power complete serial port suitable for pdas, and laptop or notebook computers. the 32 ld 5x5 qfn requires 60% less board area than a 28 ld tssop, and is nearly 20% thinner. the devices also include a noninverting always-active receiver for ?wake-up? capability. the isl4243e features an au tomatic power-down function that powers down the on-chip power-supply and driver circuits. this occurs when an attached peripheral device is shut off or the rs-232 cable is removed, conserving system power automatically without changes to the hardware or operating system. it powers up again when a valid rs-232 voltage is applied to any receiver input. table 1 summarizes the featur es of both the ISL4241E and isl4243e, while application note an9863 summarizes the features of each device comp rising the 3v rs-232 family. features ? pb-free available (rohs compliant) ? parameters fully specified for 10% tolerance supplies and full industrial temp range ? available in small qfn (5mmx5mm) package which is 60% smaller than a 28 lead tssop ? esd protection for rs-232 i/o pins to 15kv (iec61000) ? meets eia/tia-232 and v.28/v .24 specifications at 3v ? rs-232 compatible with v cc = 2.7v ? on-chip voltage converters require only four external 0.1f capacitors ? manual and automatic power-down features ? receiver hysteresis for improved noise immunity ? guaranteed minimum data rate . . . . . . . . . . . . . 250kbps ? wide power supply range . . . . . . single +2.7v to +5.5v ? low supply current in power-down state . . . . . . . . .10na applications ? any space constrained system requiring rs-232 ports - battery powered, hand-held, and portable equipment - laptop computers, notebooks - pdas and palmtops, data cables - cellular/mobile phones, digital cameras, gps receivers related literature ? technical brief tb363 ?guidelines for handling and processing moisture sensit ive surface mount devices ? ?technical brief tb379 ?thermal characterization of packages for ics? ? technical brief tb389 ?pcb land pattern design and surface mount guidelines for qfn packages? table 1. summary of features part number no. of tx. no. of rx. qfn pkg. available? no. of monitor rx. (r outb ) data rate (kbps) rx. enable function? ready output? manual power- down? automatic power- down function? ISL4241E 3 5 yes 2 250 yes no yes no isl4243e 3 5 yes 1 250 no no yes yes data sheet june 10, 2010 caution: these devices are sensitive to electrosta tic discharge; follow proper ic handling procedures. 1-888-intersil or 1-888-468-3774 | intersil (and design) is a registered trademark of intersil americas inc. copyright intersil americas inc. 2004, 2008, 2010. all rights reserved all other trademarks mentioned are the property of their respective owners
2 fn8037.7 june 10, 2010 ordering information part number part marking temp. range (c) package pkg. dwg. # ISL4241Eir isl 4241eir -40 to +85 32 ld qfn l32.5x5b ISL4241Eir-t* isl 4241eir -40 to +85 32 ld qfn tape & reel l32.5x5b ISL4241Eirz (note) isl4241 eirz -40 to +85 32 ld qfn (pb-free) l32.5x5b ISL4241Eirz-t* (note) isl4241 eirz -40 to +85 32 ld qfn tape & reel (pb-free) l32.5x5b isl4243eir isl 4243eir -40 to +85 32 ld qfn l32.5x5b isl4243eir-t* isl 4243eir -40 to +85 32 ld qfn tape & reel l32.5x5b isl4243eirz (note) isl4243 eirz -40 to +85 32 ld qfn (pb-free) l32.5x5b isl4243eirz-t* (note) isl4243 eirz -40 to +85 32 ld qfn tape & reel (pb-free) l32.5x5b *please refer to tb347 for detai ls on reel specifications. note: these intersil pb-free plastic pack aged products employ special pb-free material sets, molding compounds/die attach materi als, and 100% matte tin plate plus anneal (e3 termination finish, which is rohs compliant and compatible with both snpb and pb-free soldering operations). intersil pb-free products are msl classified at pb-fr ee peak reflow temperatures that meet or exceed the pb-free requirements of ipc/jed ec j std-020. pinouts ISL4241E (32 ld qfn) top view isl4243e (32 ld qfn) top view r1 in r2 in r3 in r4 in r5 in t1 out t2 out c1- en shdn r1 outb r2 outb r1 out r2 out t3 out t3 in t2 in t1 in r5 out r3 out r4 out v- c2- c2+ c1+ v+ gnd v cc nc 7 11 12 13 14 15 9 10 6 1 2 3 4 5 8 16 18 19 24 23 22 21 20 17 27 28 29 30 31 25 26 32 nc nc nc pd r1 in r2 in r3 in r4 in r5 in t1 out t2 out c1- forceon forceoff invalid r2 outb r1 out r2 out t3 out t3 in t2 in t1 in r5 out r3 out r4 out v- c2- c2+ c1+ v+ gnd v cc nc 7 11 12 13 14 15 9 10 6 1 2 3 4 5 8 16 18 19 24 23 22 21 20 17 27 28 29 30 31 25 26 32 nc nc nc pd ISL4241E, isl4243e
3 fn8037.7 june 10, 2010 pin descriptions pin function v cc system power supply input (2.7v to 5.5v). v+ internally generated positiv e transmitter supply (+5.5v). v- internally generated negative transmitter supply (-5.5v). gnd ground connection. this is also the potential of the thermal pad (pd). c1+ external capacitor (voltage doubl er) is connected to this lead. c1- external capacitor (voltage doubl er) is connected to this lead. c2+ external capacitor (voltage in verter) is connected to this lead. c2- external capacitor (voltage in verter) is connected to this lead. t in ttl/cmos compatible transmitter inputs. t out 15kv esd protected , rs-232 level (nominally 5.5v) transmitter outputs. r in 15kv esd protected , rs-232 compatible receiver inputs. r out ttl/cmos level receiver outputs. r outb ttl/cmos level, noninverting, always enabled receiver outputs. invalid active low output that indicates if no valid rs -232 levels are present on any receiver input. forceoff active low to shut down transmitters and on-chip power supply. this overrides any automatic ci rcuitry and forceon (see table 2) . forceon active high input to override automatic power-down circuitry thereby keeping tran smitters active. (forceoff must be high). en active low receiver enable control. shdn active low input to shut down transmitters and on-boar d power supply, to place device in low power mode. nc no connection pd exposed thermal pad. connect to gnd. ISL4241E, isl4243e
4 fn8037.7 june 10, 2010 typical operating circuits ISL4241E isl4243e 26 v cc t1 out t2 out t3 out t1 in t2 in t3 in t 1 t 2 t 3 0.1 f + 0.1 f + 0.1 f 12 11 6 7 10 8 28 23 27 31 v+ v- c1+ c1- c2+ c2- + 0.1 f 29 30 r1 out r1 in 1 5k r2 out r2 in 2 17 5k r3 out r3 in 3 15 5k r4 out r4 in 4 14 5k r5 out r5 in r 5 5 13 5k 18 r2 outb c 1 c 2 + c 3 c 4 en shdn 22 gnd 21 +3.3v + 0.1 f 19 24 v cc ttl/cmos logic rs-232 levels rs-232 levels r1 outb 20 r 1 r 2 r 3 r 4 levels 26 v cc t1 out t2 out t3 out t1 in t2 in t3 in t 1 t 2 t 3 0.1 f + 0.1 f + 0.1 f 12 11 6 7 10 8 28 23 27 31 v+ v- c1+ c1- c2+ c2- + 0.1 f 29 30 r1 out r1 in 1 5k r2 out r2 in 2 17 5k r3 out r3 in 3 15 5k r4 out r4 in 4 14 5k r5 out r5 in r 5 5 13 5k 18 r2 outb c 1 c 2 + c 3 c 4 forceon forceoff 22 gnd 21 +3.3v + 0.1 f 19 24 v cc ttl/cmos logic rs-232 levels rs-232 levels r 1 r 2 r 3 r 4 20 invalid to power control levels logic ISL4241E, isl4243e
5 fn8037.7 june 10, 2010 absolute maximum rati ngs thermal information v cc to ground. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3v to 6v v+ to ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3v to 7v v- to ground. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +0.3v to -7v v+ to v- . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14v input voltages t in , forceoff , forceon, en , shdn . . . . . . . . . -0.3v to 6v r in . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25v output voltages t out . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.2v r out , invalid . . . . . . . . . . . . . . . . . . . . . . . . -0.3v to v cc +0.3v short circuit duration t out . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . continuous esd rating . . . . . . . . . . . . see ?esd performance? on page 7 thermal resistance (typical, notes 1, 2) ja ( c/w) jc ( c/w) 32 ld qfn package. . . . . . . . . . . . . . . 32 2.0 maximum storage temperature range . . . . . . . . . .-65 c to +150 c pb-free reflow profile. . . . . . . . . . . . . . . . . . . . . . . . .see link below http://www.intersil.com/pbfree/pb-freereflow.asp operating conditions temperature range ISL4241Eir, isl4243eir . . . . . . . . . . . . . . . . . . .-40 c to +85 c caution: do not operate at or near the maximum ratings listed fo r extended periods of time. exposure to such conditions may adv ersely impact product reliability and result in failures not covered by warranty. note: 1. ja is measured in free air with the component mounted on a high ef fective thermal conductivity te st board with ?direct attach? fe atures. see tech brief tb379, and tech brief tb389. 2. for jc , the ?case temp? location is the center of the exposed metal pad on the package underside. electrical specifications test conditions: v cc = 3v to 5.5v, c 1 to c 4 = 0.1f; unless otherwise specified. typicals are at t a = +25c parameter test conditions temp (c) min (note 4) typ max (note 4) units dc characteristics operating voltage range full 2.7 - 5.5 v supply current, automatic power-down all r in open, forceon = gnd, forceoff = v cc (isl4243e only) 25 - 3 300 na full - 50 300 na supply current, power-down all r in open, forceoff = shdn = gnd 25 - 3 300 na full - 50 300 na supply current, automatic power-down disabled all outputs unloaded, forceon = forceoff = shdn = v cc , v cc = 3.0v 25 - 0.3 1.0 ma full - 0.3 1.5 ma logic and transmitter inputs and receiver outputs input logic threshold low t in , forceon, forceoff , en , shdn full - - 0.8 v input logic threshold high t in , forceon, forceoff , en , shdn , v cc = 3.6v full 2.0 - - v input leakage current t in , forceon, forceoff , en , shdn full - 0.01 1.0 a output leakage current forceoff = gnd (isl4243e) or en = v cc (ISL4241E) full - 0.05 10 a transmitter input hysteresis 25 - 0.5 - v output voltage low i out = 1.6ma full - - 0.4 v output voltage high i out = -1.0ma full v cc - 0.6 v cc - 0.1 - v automatic power-down (isl4243e only, forceon = gnd, forceoff = v cc ) receiver input thresholds to enable transmitters isl4243e powers up (see figure 7) full -2.7 - 2.7 v receiver input thresholds to disable transmitters isl4243e powers down (see figure7) full -0.3 - 0.3 v invalid output voltage low i out = 1.6ma full - - 0.4 v invalid output voltage high i out = -1.0ma full v cc - 0.6 - - v receiver threshold to transmitters enabled delay (t wu ) full - 20 100 s ISL4241E, isl4243e
6 fn8037.7 june 10, 2010 receiver positive or negative threshold to invalid high delay (t invh ) 25 - 0.5 1 s full - 0.9 1.5 s receiver positive or negative threshold to invalid low delay (t invl ) 25 - 30 50 s full - 40 60 s receiver inputs input voltage range full -25 - 25 v input threshold low v cc = 3.0v full - 1.0 0.6 v input threshold high v cc = 3.6v full 2.4 1.5 - v input hysteresis 25 - 0.5 - v input resistance full 3 5 7 k transmitter outputs output voltage swing all transmitter outputs loaded with 3k to ground full 5.0 5.4 - v output resistance v cc = v+ = v- = 0v, transmitter output = 2v full 300 10m - output short-circuit current full - 35 60 ma output leakage current v out = 12v, v cc = 0v or 3v to 5.5v, automatic power-down or forceoff = shdn = gnd full - - 25 a timing characteristics maximum data rate r l = 3k , c l = 1000pf, one transmitter switching full 250 500 - kbps receiver propagation delay receiver input to receiver output, c l = 150pf t phl 25 - 0.15 0.3 s full - 0.2 0.35 s t plh 25 - 0.3 0.5 s full - 0.35 0.55 s receiver skew t phl - t plh , c l = 150pf 25 - 120 250 ns full - 150 300 ns transmitter propagation delay transmitter input to transmitter output, c l = 1000pf, r l = 3k t phl 25 - 0.75 1 s full - 0.85 1.1 s t plh 25 - 0.8 1 s full - 0.9 1.1 s transmitter skew t phl - t plh (note 3), r l = 3k , c l = 1000pf 25 - 50 200 ns full - 100 250 ns receiver output enable time normal operation, r l = 1k to 0.5v cc , c l = 15pf 25 - 200 350 ns full - 200 400 ns receiver output disable time normal operation, r l = 1k to 0.5v cc , c l = 15pf 25 - 350 500 ns full - 400 600 ns transmitter output enable time normal operation, r l = 3k , c l = 1000pf 25 - 25 40 s full - 30 50 s transmitter output disable time normal operation, r l = 3k , c l = 1000pf 25 - 2.5 4 s full - 2.7 4 s electrical specifications test conditions: v cc = 3v to 5.5v, c 1 to c 4 = 0.1f; unless otherwise specified. typicals are at t a = +25c (continued) parameter test conditions temp (c) min (note 4) typ max (note 4) units ISL4241E, isl4243e
7 fn8037.7 june 10, 2010 detailed description the ISL4241E and isl4243e both operate from a single +2.7v to +5.5v supply, guarantee a 250kbps minimum data rate, require only four smal l external 0.1f capacitors, feature low power consumption, and meet all ela rs-232c and v.28 specifications even with v cc = 3.0v. the circuit is divided into three sections: the charge pump, the transmitters, and the receivers. charge-pump intersil?s new ISL4241E, isl4243e devices utilize regulated on-chip dual charge pumps as voltage doublers, and voltage inverters to generate 5.5v transmitter supplies from a v cc supply as low as 3.0v. this allows them to maintain rs-232 compliant output levels over the 10% tolerance range of 3.3v powered systems. the effi cient on-chip power supplies require only four small, extern al 0.1f capacitors for the voltage doubler and inverter functions. the charge pumps operate discontinuously (i.e., they turn off as soon as the v+ and v- supplies are pumped up to the nominal values), resulting in signifi cant power savings. transmitters the transmitters are proprietary, low dropout, inverting drivers that translate ttl/cm os inputs to eia/tia-232 output levels. coupled with the on-chip 5.5v supplies, these transmitters deliver tr ue rs-232 levels over a wide range of single supply system voltages. all transmitter outputs disable and assume a high impedance state when the device enters the power-down mode (see table 2). these outputs may be driven to 12v when disabled. the devices guarantee a 250kbps data rate for full load conditions (3k and 1000pf), v cc 3.0v, with one transmitter operating at full speed. under more typical conditions of v cc 3.3v, r l = 3k , and c l = 250pf, one transmitter easily operates at 900kbps. transmitter inputs float if left unconnected, and may cause i cc increases. connect unused inputs to gnd for the best performance. receivers all the ISL4241E, isl4243e?s devices contain standard inverting receivers that are three-state via the en or forceoff control lines. additionally, the ISL4241E, isl4243e?s products include noninverting (monitor) receivers (denoted by the r outb label) that are always active, regardless of the state of any control lines. all the receivers convert rs-232 signals to cmos output levels and accept inputs up to 25v while presenting the required 3k to 7k input impedance (see figure 1) even if the power is off (v cc = 0v). the receivers? schmitt trigger input stage uses hysteresis to increase noise immunity and decrease errors due to slow input signal transitions. the ISL4241E inverting receivers disable only when en is driven high. isl4243e receivers disable during forced (manual) power-down, but not during automatic power-down (see table 2). transition region slew rate v cc = 3v to 3.6v, r l = 3k to 7k , measured from 3v to -3v or -3v to 3v c l = 150pf to 2500pf 25 4 9 30 v/s full 4 8 30 v/s c l = 150pf to 1000pf 25 6 11 30 v/s full 6 10 30 v/s esd performance rs-232 pins (t out , r in ) human body model 25 - 15 - kv iec61000-4-2 contact discharge 25 - 8 - kv iec61000-4-2 air gap discharge 25 - 15 - kv all other pins human body model 25 - 2 - kv note: 3. transmitter skew is measured at t he transmitter zero crossing points. 4. parameters with min and/or max limits are 100% tested at +25 c, unless otherwise specified. temperature limits established by characterization and are not production tested. electrical specifications test conditions: v cc = 3v to 5.5v, c 1 to c 4 = 0.1f; unless otherwise specified. typicals are at t a = +25c (continued) parameter test conditions temp (c) min (note 4) typ max (note 4) units r xout gnd v rout v cc 5k r xin -25v v rin +25v gnd v cc figure 1. inverting receiver connections ISL4241E, isl4243e
8 fn8037.7 june 10, 2010 ISL4241E and isl4243e monitor receivers remain active even during manual power-down, making them extremely useful for ring indicator monitoring. standard receivers driving powered down peripherals must be disabled to prevent current flow through the peripheral?s protection diodes (see figures 2 and 3). this renders them useless for wake-up functions, but the corresponding monitor receiver can be dedicated to this task as shown in figure 3. low power operation these 3v devices require a nominal supply current of 0.3ma, even at v cc = 5.5v, during normal operation (not in power-down mode). this is considerably less than the 5ma to 11ma current required by comparable 5v rs-232 devices, allowing users to reduce system power simply by switching to this new family. power-down functionality the already low current requi rement drops significantly when the device enters power-down mode. in power-down, supply current drops to 10na, because the on-chip charge pump turns off (v+ collapses to v cc , v- collapses to gnd), and the transmitter outputs three-state. inverting receiver outputs disable only in manual power-down; refer to table 2 for details. this micro-power mode makes the ISL4241E and isl4243e ideal for battery powered and portable applications. table 2. power-down and enable logic truth table rs-232 signal present at receiver input? shdn or forceoff input forceon input en input transmitter outputs receiver outputs r outb outputs invalid output mode of operation ISL4241E n.a. l n/a l high-z active active n/a manual power-down n.a. l n/a h high-z high-z active n/a manual power-down w/receiver disabled n.a. h n/a l active active active n/a normal operation n.a. h n/a h active high-z active n/a normal operation w/receiver disabled isl4243e no h h n/a active active active l normal operation (auto power-down disabled) yes h l n/a active active active h normal operation (auto power-down enabled) no h l n/a high-z active active l power-down due to auto power-down logic yes l x n/a high-z high-z active h manual power-down no l x n/a high-z high-z active l manual power-down figure 2. power drain through powered down peripheral old v cc powered gnd shdn = gnd v cc rx tx v cc current v out = v cc flow rs-232 chip down uart ISL4241E, isl4243e
9 fn8037.7 june 10, 2010 software controlled (manual) power-down most devices in the ISL4241E, isl4243e family provide pins that allow the user to force the ic into the low power, standby state. on the ISL4241E, the power-down control is via a simple shutdown (shdn ) pin. driving this pin high enables normal operation, while driving it low forces the ic into it?s power-down state. connect shdn to v cc if the power-down function isn?t needed. note that all the receiver outputs remain enabled during shutdown (see table 2). for the lowest power consumption during power-down, the receivers should also be disabled by driving the en input high (see next section, and figures 2 and 3). the isl4243e utilize a two pin approach where the forceon and forceoff inputs determine the ic?s mode. for always enabled operation, forceon and forceoff are both strapped high. to switch between active and power-down modes, under logic or software control, only the forceoff input need be driven. the forceon state isn?t critical, as forceoff dominates over forceon. nevertheless, if strictly manual control over power-down is desired, the user must strap forceon high to disable the automatic power-down circuitry. the isl4243e inverting (standard) receiver outputs also disable when the device is in manual power-dow n, thereby eliminating the possible current path through a shutdown peripheral?s input protection diode (see figures 2 and 3). connecting forceoff and forceon together disables the automatic power-down featur e, enabling them to function as a manual shutdown input (see figure 4). with any of the previous mentioned control schemes, the time required to exit power-down, and resume transmission is only 100s. a mouse, or other application, may need more time to wake up from shutdown. if automatic power-down is being utilized, the rs-232 devic e will reenter power-down if valid receiver levels aren?t reestablished within 30s of the isl4243e powering up. figure 5 illustrates a circuit that keeps the isl4243e from init iating automatic power-down for 100ms after powering up. this gives the slow-to-wake peripheral circuit time to reestablish valid rs-232 output levels. invalid output (isl4243e only) the invalid output always indicates whether or not a valid rs-232 signal (see figure 6) is present at any of the receiver inputs (see table 2), giving the user an easy way to determine when the interface block should power down. invalid receiver levels occur whenever the driving peripheral?s outputs are shut off (powered down) or when the rs-232 interface cable is disconnected. in the case of a disconnected interface cable where all the receiver inputs are floating (but pulled to gnd by the internal receiver pull down resistors), the invalid logic detects the invalid levels and drives the output low. the power management logic figure 3. disabled receivers prevent power drain ISL4241E transition r x t x r2 outb r2 out t1 in forceoff = gnd v cc v cc to r2 in t1 out v out = hi-z powered detector down uart wake-up logic or shdn = gnd, en = v cc isl4243e figure 4. connections for manual power-down when no valid receiver signals are present pwr forceoff invalid cpu i/o forceon isl4243e mgt logic uart figure 5. circuit to prevent auto power-down for 100ms after forced powerup isl4243e forceoff forceon power master power-down line 1m 0.1 f management unit ISL4241E, isl4243e
10 fn8037.7 june 10, 2010 then uses this indicator to power down the interface block. reconnecting the cable restores valid levels at the receiver inputs, invalid switches high, and the power management logic wakes up the interface block. invalid can also be used to indicate the dtr or ring indicator signal, as long as the other receiver inputs are floating, or driven to gnd (as in the case of a powered down driver). invalid switches low after invalid levels have persisted on all of the receiver inputs for more than 30s (see figure 7). invalid switches back high 1s after detecting a valid rs-232 level on a receiver input. invalid operates in all modes (forced or automatic power -down, or forced on), so it is also useful for systems employing manual power-down circuitry. when automatic power-down is utilized, invalid = 0 indicates that the isl4243e is in power-down mode. automatic power-down (isl4243e only) even greater power savings is available by using the isl4243e which features an automatic power-down function. when no valid rs-232 voltages (see figure 5) are sensed on any receiver input for 30s, the charge pump and transmitters power-down, ther eby reducing supply current to 10na. invalid receiver levels occur whenever the driving peripheral?s outputs are shut off (powered down) or when the rs-232 interface cable is disconnected. the isl4243e powers back up whenever it detects a valid rs-232 voltage level on any receiver input. this automatic power-down feature provides additional system power savings without changes to the exis ting operating system. automatic power-down operates when the forceon input is low, and the forceoff input is high. tying forceon high disables automatic power-down, but manual power-down is always available via the overriding forceoff input. table 2 summarizes the automatic power-down functionality. the time to recover from automatic power-down mode is typically 100s. capacitor selection the charge pumps require 0.1f, or greater, capacitors for proper operation. increasing the capacitor values (by a factor of 2) reduces ripple on the transmitter outputs and slightly reduces power consumption. when using minimum required capacitor values, make sure that capacitor values do not degrade excessively with temperature. if in doubt, use ca pacitors with a larger nominal value. the capacitor?s equivalent series resistance (esr) usually rises at low temperat ures and it influences the amount of ripple on v+ and v- . power supply decoupling in most circumstances a 0.1f bypass capacitor is adequate. in applications that are particularly sensitive to power supply noise, decouple v cc to ground with a capacitor of the same value as the charge-pump capacitor c 1 . connect the bypass capacitor as close as possible to the ic. transmitter outputs when exiting power-down figure 8 shows the response of two transmitter outputs when exiting power-down mode. as they activate, the two transmitter outputs properly go to opposite rs-232 levels, with no glitching, ringing, nor undesirable transients. each transmitter is loaded with 3k in parallel with 2500pf. note that the transmitters enable only when the magnitude of the supplies exceed approximately 3v. figure 6. definition of valid rs-232 receiver levels 0.3v -0.3v -2.7v 2.7v invalid level - power-down occurs after 30 s valid rs-232 level - isl4243e is active valid rs-232 level - isl4243e is active indeterminate - power-down may or indeterminate - power-down may or may not occur may not occur receiver inputs transmitter outputs invalid output v+ v cc 0 v- v cc 0 t invl t invh invalid region } figure 7. automatic power-down and invalid timing diagrams autopwdn pwr up ISL4241E, isl4243e
11 fn8037.7 june 10, 2010 operation down to 2.7v the ISL4241E, isl4243e transmitter outputs meet rs-562 levels (3.7v), at the full data rate, with v cc as low as 2.7v. rs-562 levels typically ensure inter operability with rs-232 devices. high data rates the ISL4241E, isl4243e maintain the rs-232 5v minimum transmitter output voltages even at high data rates. figure 9 details a transmitter loopback test circuit, and figure 10 illustrates the loopback test result at 120kbps. for this test, all transmitters were simultaneously driving rs-232 loads in parallel with 1000pf, at 120kbps. figure 11 shows the loopback results for a single transmitter driving 1000pf and an rs-232 load at 250kbps. the static transmitters were also loaded with an rs-232 receiver. interconnection with 3v and 5v logic the ISL4241E, isl4243e directly interface with 5v cmos and ttl logic families. nevertheless, with the ISL4241E, isl4243e at 3.3v, and the logic supply at 5v, ac, hc, and cd4000 outputs can drive ISL4241E, isl4243e inputs, but ISL4241E, isl4243e outputs do not reach the minimum v ih for these logic families. see table 3 for more information. figure 9. transmitter loopback test circuit time (20 s/div) t1 t2 2v/div. 5v/div. v cc = +3.3v forceoff figure 8. transmitter outputs when exiting power-down c1 to c4 = 0.1 f ISL4241E v cc forceoff or shdn c 1 c 2 c 4 c 3 + + + + 1000pf v+ v- 5k t in r out c1+ c1- c2+ c2- r in t out + v cc 0.1 f v cc forceon isl4243e figure 10. loopback test at 120kbps figure 11. loopback test at 250kbps table 3. logic family compatibility with various supply voltages system power-supply voltage (v) v cc supply voltage (v) compatibility 3.3 3.3 compatible with all cmos families. 5 5 compatible with all ttl and cmos logic families. t1 in t1 out r1 out 5 s/div v cc = +3.3v 5v/div c1 to c4 = 0.1 f t1 in t1 out r1 out 2 s/div 5v/div. v cc = +3.3v c1 - c4 = 0. f ISL4241E, isl4243e
12 fn8037.7 june 10, 2010 15kv esd protection all pins on ISL4241E, isl4243e devices include esd protection structures, but t he rs-232 pins (transmitter outputs and receiver inputs) incorporate advanced structures which allow them to survive esd events up to 15kv. the rs-232 pins are particularly vulnerable to esd damage because they typically connect to an exposed port on the exterior of the finished product. simply touching the port pins, or connecting a cable, can cause an esd event that might destroy unprot ected ics. these new esd structures protect the device wh ether or not it is powered up, protect without allowing any latchup mechanism to activate, and don?t interfere with rs-232 signals as large as 25v. human body mode l (hbm) testing as the name implies, this test method emulates the esd event delivered to an ic during human handling. the tester delivers the charge through a 1.5k current limiting resistor, making the test less severe th an the iec61000 test which utilizes a 330 limiting resistor. the hbm method determines an ics ability to withstand the esd transients typically present during handling and manufacturing. due to the random nature of these ev ents, each pin is tested with respect to all other pins. the rs-232 pins on ?e? family devices can withstand hbm esd events to 15kv. iec61000-4-2 testing the iec61000 test method applies to finished equipment, rather than to an individual ic. therefore, the pins most likely to suffer an esd event are t hose that are ex posed to the outside world (the rs-232 pins in this case), and the ic is tested in its typical application configuration (power applied) rather than testing each pin-to -pin combination. the lower current limiting resistor coupled with the larger charge storage capacitor yields a test that is much more severe than the hbm test. the extra esd protection built into this device?s rs-232 pins allows the design of equipment meeting level 4 criteria with out the need for additional board level protection on the rs-232 port. air-gap discharge test method for this test method, a charged probe tip moves toward the ic pin until the voltage arcs to it. the current waveform delivered to the ic pin depends on approach speed, humidity, temperature, etc., so it is difficult to obtain repeatable results. the ?e? device rs-232 pins withstand 15kv air-gap discharges. contact discharge test method during the contact discharge test, the probe contacts the tested pin before the probe tip is energized, thereby eliminating the variables associated with the air-gap discharge. the result is a more repeatable and predictable test, but equipment limits prevent testing devices at voltages higher than 8kv. all ?e? family devices survive 8kv contact discharges on the rs-232 pins. 5 3.3 compatible with act and hct cmos, and with ttl. ISL4241E, isl4243e outputs are incompatible with ac, hc, and cd4000 cmos inputs. table 3. logic family compatibility with various supply voltages (continued) system power-supply voltage (v) v cc supply voltage (v) compatibility typical performance curves v cc = 3.3v, t a = +25c figure 12. transmitter output voltage vs load capacitance figure 13. slew rate vs load capacitance -6 -4 -2 0 2 4 6 1000 2000 3000 4000 5000 0 load capacitance (pf) transmitter output voltage (v) 1 transmitter at 250kbps v out + v out - other transmitters at 30kbps load capacitance (pf) slew rate (v/ s) 0 1000 2000 3000 4000 5000 5 10 15 20 25 +slew -slew ISL4241E, isl4243e
13 all intersil u.s. products are manufactured, asse mbled and tested utilizing iso9000 quality systems. intersil corporation?s quality certifications ca n be viewed at www.intersil.com/design/quality intersil products are sold by description only. intersil corpor ation reserves the right to make changes in circuit design, soft ware and/or specifications at any time without notice. accordingly, the reader is cautioned to verify that data sheets are current before placing orders. information furnishe d by intersil is believed to be accurate and reliable. however, no responsibility is assumed by intersil or its subsidiaries for its use; nor for any infringements of paten ts or other rights of third parties which may result from its use. no license is granted by implication or otherwise under any patent or patent rights of intersil or its subsidiari es. for information regarding intersil corporation and its products, see www.intersil.com fn8037.7 june 10, 2010 die characteristics substrate and qfn thermal pad potential (powered up): gnd transistor count: ISL4241E, isl4243e: 464 process: si gate bicmos figure 14. supply current vs load capacitance when transmitting data figure 15. supply current vs supply voltage typical performance curves v cc = 3.3v, t a = +25c (continued) 10 15 20 25 30 45 35 40 0 1000 2000 3000 4000 5000 load capacitance (pf) supply current (ma) 20kbps 250kbps 120kbps supply current (ma) 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 0 0.5 1.0 1.5 2.0 supply voltage (v) 2.5 3.0 3.5 no load all outputs static ISL4241E, isl4243e
14 fn8037.7 june 10, 2010 ISL4241E, isl4243e package outline drawing l32.5x5b 32 lead quad flat no-lead plastic package rev 2, 11/07 located within the zone indicated. the pin #1 identifier may be unless otherwise specified, tolerance : decimal 0.05 tiebar shown (if present) is a non-functional feature. the configuration of the pin #1 identifier is optional, but must be between 0.15mm and 0.30mm from the terminal tip. dimension b applies to the metallized terminal and is measured dimensions in ( ) for reference only. dimensioning and tolerancing conform to amse y14.5m-1994. 6. either a mold or mark feature. 3. 5. 4. 2. dimensions are in millimeters. 1. notes: bottom view detail "x" side view typical recommended land pattern top view 5.00 a 5.00 b index area pin 1 6 (4x) 0.15 32x 0.40 0.10 4 a 32x 0.23 m 0.10 c b 16 9 4x 0.50 28x 3.5 6 pin #1 index area 3 .30 0 . 15 0 . 90 0.1 base plane see detail "x" seating plane 0.10 c c 0.08 c 0 . 2 ref c 0 . 05 max. 0 . 00 min. 5 ( 3. 30 ) ( 4. 80 typ ) ( 28x 0 . 5 ) (32x 0 . 23 ) ( 32x 0 . 60) + 0.07 - 0.05 17 25 24 8 1 32

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