19-2370; Rev 2; 10/91 MA AXI/VI Complete, +5V-Powered, Isolated, Dual RS-232 Transceiver Module General Description The MAX252 complete, electrically-isolated, dual RS-232 transmitter/receiver system requires no external compo- nents. By combining many functions in one package, the cost and complexity of an isolated digital interface are greatly reduced. A single +5V supply powers both sides of the interface Transceivers, optocouplers, and a transformer in one low-cost package provide a complete interface up to 9600 bits/sec. Additional pins provide low-power shutdown and a high-impedance state for both transmitter outputs. The MAX252A withstands 130Vams (continuous), 1260Vems (1 min.) or 1520Veams (1 sec.) and is intended for applications where very high transient voltages, dif- ferential ground potentials or noise may be encountered. The MAX252A is UL recognized. The MAX252B is in- tended for less stringent applications and is rated for 500Vems (1 min.) or 600VAms (1 Sec.). Receivers and line drivers (transmitters) meet EIA RS-232D and CCITT V.28 specifications. The MAX252 is supplied in 40-pin plastic DIP packages in commercial (0C to +70C) and extended (-40C to +85C) tempera- ture ranges Applications High-Noise Environments Automatic Test Equipment Differential Ground Potentials Typical Application Vv 1 v7, \ \ uP Data "] UART MAX MAX25? HANDSHAKE | 1 LOGIC [ | t Sint = ISOLATION BARRIER Fy " Soo 8 ooocas / / | | og > 2 > bbosbs peoceo | Isolated uP to RS 232 Interface Features @ Isolated Data Interface @ No External Components @ Single +5V Supply @ 50,:W Low-Power Shutdown @ Two Transmitters and Two Receivers @ UL Recognized (MAX252A) - File E118032 to UL1577 Ordering Information PART TEMP. RANGE PIN-PACKAGE | MAX252ACHL OC to +70C AO Plastic Module | MAX252BCHL OC to +70C -40C to +85C 40 Plastic Module MAX252AEHL AO Plastic Module MAX252BEHL -40C to +85 C 40 Plastic Module | L Pin Configuration TOP VIEW oN R1oul | 7 40 AC b2[ 2] 39 V SHON [ 3] [3e' ISO GND Dt fa] [37] Vi Voc | 2] 36 Maul 12L08 [6] 35] T2oui 12in (7 | 34" ALIN THIN E WO [333] R2in ItorL9 MAK2528 Vesa) yy GNO 10) 31, BYP EN [Ty [20] R21 DR R2ou1 [124 29 RT DR Rapin [13] 8] T2DIN Rioin [14] 21 Voi Thep [18 16, T1001 LED COM [15] 25] ISO DET COM Tao ire 4 T2pH Riper [13] 23) Blin DEI COM [i 29 ISO LED. COM Raver |? er, Reve MAXIM Maxim Integrated Products 1 Call toll free 1-800-998-8800 for free samples or literature. cSCXVINMAX252 Complete, +5V-Powered, Isolated, Dual RS-232 Transceiver Module ABSOLUTE MAXIMUM RATINGS Voltages with respect to GND (pin 10) LED Forward Continuous Current (pins 15, 17, 21. 23) 30mA Supply Voltage, VCC 1... eee .. -0.3V to +6V Power Dissipation input Voltage Plastic DIP (derate 10mW/C above +70C) .. . 650mMW Pins 3, 7, 8, 11, 13, 14, 18, 20 _.. -0.3V to (Voc +0.3V) Operating Temperature Ranges Voltages with respect to ISO GND (pin 38) MAX252ACHL/BCHL . OC to +70C RS-232 Input Voltage (pins 33, 34) ........... -30V to +30V MAX252AEHL/BEHL .... 40C to +85C RS-232 Applied Output Voltage (pins 35, 36)... -15V to +15V Storage Temperature Range -65'C to + 150C Pins 32, 87 (V+)... Leen ee +15V Lead Temperature (soldering, 10 sec ) +300 'C Pins 24, 26,31 0.0.0.0... 0000 Deets V+ RS-232 Transmitter outputs may be shorted individually and indefinitely to ISO GND. Stresses beyond those listed under Absolute Maximum Ratings" may cause permanent damage to the device. [hese are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational section of the specifications 1s nol impled. Exposure to absolute maximum rating conditions for extended periods may affect device reliability ELECTRICAL CHARACTERISTICS (Vcc = +5V 10%, TA = TMIN to Tmax, unless otherwise noted.) a __ = [ PARAMETER | symBoL | CONDITIONS MIN TYP MAX| UNITS | ISOLATION (Note 1) 7 1sec. | 4520 | | rrr 1 min, (Note 2) 1260 | | Test Voltage VISO Continuous (Note 2) 130 VRMS _ , TO 1 1 sec. | 600 | MAX252B | ee it min. (Note 2) 500 10 sec., Viso = 500VAMs. 60H2z, . | Leakage Current | Ta = 425C - | 10 50 | HARMS : , Ta = +25'C ( Isolation Resistance 500Vbc | 19' 2 | Capacitance _ _ 7 ov 10 pF _ _ jt __ _ . POWER SUPPLY | _ TT Te | Ti Te Btn _ Ta = 425C, TIN. T2IN, RUIN. R2IN = Voc 60 90 | Operating Supply Current Ioc mA peranngsupe | SHDN = OV | THin, T2IN, RIN, RIN = 0 | 8 15 Shutdown Supply Current Ics | SHDN = Voc, TA = +25C _ _ 1 10 vA | Fr IEN. _ | | EN SHDN Input Current ISHON | Input = GND to Vcc 0.001 | HA | TTL/CMOS INPUTS/OUTPUTS ; 7 TTL/CMOS Input Pull-Up Current | Ip VIN = OV | 4 20 | HA | TTLICMOS Output Voltage Low , Voi | lour=3.2mA _ 04 vo | TTL/CMOS Output Voltage High VOH ___ lout =-1.0mMA _ | 3.5 Vv | | Input Logic Threshold High VIH Tin, T2In. EN. SHDN _ __ 1.8 24 | Vv Input Logic Threshold Low , ve TIN, T2In, EN, SHDN _ | 0.8 13 V | Input Hysteresis TAIN, T2IN / 0.5 | vo | Leakage Current, EN _ | Ouiputbisabled IL T1in, T2in; EN or SHDN = Voc | 10 | HA |_Input Capacitance | Cin | TIN, T21N _ | 5 | pF | Note 1: Pins 1-20 tied together and pins 21-40 tied together Note 2: Value derived from 1 sec. test 2Complete, +5V-Powered, Isolated, Dual RS-232 Transceiver Module ELECTRICAL CHARACTERISTICS (continued) (Voc = +5V 10%, Ta = TMIN to Tmax. unless otherwise noted.) PARAMETER MAXLAA | SYMBOL | CONDITIONS | MIN TYP MAX | UNITS RS-232 CHARACTERISTICS Tout, T2ouT. RS-232 Output Voltage Swing Vpp RL = 3kQ2 to ISO +5 +7.2 | V V+ = V- = 0V or SHDN = Vcc, RS-232 Output Leakage Current Tour t2oure H18V -100 +100 uA RS-232 Input Threshold High | Rin, R2IN 1.8 3.0 RS-232 Input Threshold Low RIN, R2IN 0.6 12 RS-232 Input Hysteresis R1InN, R2IN 06 - V RS-232 Input Resistance R1in, R2in, Ta = +25C 3 7 kQ ans Ru = 3kQ, CL = 2500pF Sample Tested . Transmitter Output Slew Rate SR Measured from +3v to -3V or -3V to +3V 3 30 Vius tR RS-232 to TTL 24 Propagation Delay l Oo HS tT TTL to RS-232 20 Sample Tested Transmission Rate | RL = 3kQ 9600 19200 Bits/sec CL = 2500pF_ Typical Operating Circuit | 4} 01 : AC] 40 BV 5] Voc ylic va [ 37. 32 DC-DC} 2 le ISO-PWR 3] SHDN <1 S| v-1 a9 cS LA, = 2} 02 BYP] 31 . 8] Tin + + [So Tout] 36 RS-232 QUT TTLIN 7 TaN D : bse Tour | 35 11 EN I ~ 4] Rtour irl Rlin] 34 . TIL OUT RS-232 IN 12] R2our 4. R2in| 33 | 9] Tor Los Tpin [27 [15] THep | Tier] 26] 8] T2.pr Tapin| 28 17] T2ir0 Tapet | 24 | 18 | Riper mam Ritor| 29 [44] Ripin MAK252 RIL ED | 23 | 20] R2pet Racor | 30. [13] Reo Raco | 21! 10] GND ISO GND [38 16 | LED COM | ISO DET COM] 29, 19 | DET COM ISO LED COM 22, = ! Vv ISOLATION BARRIER cSCXVNMAX252 Complete, +5V-Powered, Isolated, Dual RS-232 Transceiver Module Typical Operating Characteristics MAX252 TRANSMITTER MAX252 TRANSMITTER SLEW RATE SLEW RATE MAX252 ENABLE, DISABLE TIME vs. TEMPERATURE vs. LOAD CAPACITANCE vs. TEMPERATURE 18 14 1 300 i Roa | a ae | CL = 2.50 12 i Voc = +5.5V _| 250 : _ _ 10 12 eS 200 | = | fo = 8 z & 0 = 2 150 = 8 = 6 = a 6 B 4 100 | ab Veo -s5. at lt 2 = 8W, Voc = 15V 50 | fo P| | 0 L 0 _ 0 5-25 0) 58075100125 0 2000 4000 ~= 6000-8000 10000 56-25 0) 25 50 7H 100128 TEMPERATURE (C) LOAD CAPACITANCE (pF) TEMPERATURE ( (i) POWER-UP DELAY TO TIME FROM SHUTDOWN TO TRANSMITTER OUTPUTS POWER-UP +5V Voc - 15V 5 ++ -Toutloap 5k82 4 oV SHUTDOWN 0 5 > = 3 | | > TRANSMITTER OUTPUTS 5 |+- | 10 TouILOAD 5KQ | 7 ims/DIV 500us/DIV 4 MAXIMComplete, +5V-Powered, Isolated, Dual RS-232 Transceiver Module Pin Description PIN: # NAME | to FUNCTION | | Receiver #1 Output; TTL/CMOS logic 1 RTOUT levels 4 2 De Internal Connection. Leave this pin unconnected. Do not ground. Shutdown. When high, turns off the | 3 SHDN oscillator and disconnects driver in- puts. Ground for normal operation. | 4 Dt Internal Connection. Leave this pin un- a [ec connected. Do Do not ot ground. _ 5 Veco | +8V +5V Supply Voltage 6 T2LpR_| Transmitter #2 LEDC Driver | Transmitter #2 Input; TTL/CMOS logic 7 T2IN | levels Transmitter #1 input: TTLICMOS OS ogia | 8 TIN |_levels 9 T1LDR Transmitter #1 LED Driver | 10 GND Ground, | Output Enable If Hic High, TILDR. 7 1 | EN T2Lpr, Rout, and R2ouT go to high- impedance state. Ground for normal | | operation. Receiver #2 Output: ut; TTLICMOS logic 12 ROUT | levels 13 R2dIN Receiver #2 Detector Input \ 14 RIDIN | Receiver #1 Detector tor Input | 15 TILED | Tt LED Anode Je Input Common TILED, T2LED Cathode Tie | 16_[PEP COW to Ground, 17 T2LED T2 LED Anode Input a | 1 Ripet , Rt Photodiode Cathode Output | 19 | DET COM Common R1pet, R2pET Anode. Tie | Raver_| [2 MAKIM to Ground R2 Photodiode Cathode Output 7 FUNCTION | pine | NAME | er ROLE. | R2 LED Cathode Input | 29 ISOLED | Common R1Lep. R2LED Cathode. Tie | COM | tolsolated Ground T Ritep | R1LED Cathode Input a 24 T2DET | T2Pr Photodiode Ancde Output 25 SO DET ; Common 7T1peT, T2bET LED Anode | | | COM | Tie tolsolated Ground | Pr | _ Tbin | Transmitter #1 Detector Input TADET T1 Photodiode Anode Output 2a T2dIN- Transmitter #2 Detector Input R1iN RS-232 Receiver #1 Input RS-232 Transmitter #2 Output 35 T20uUT =n RS-232 Transmitter #1 Output | T10uT V+ Isolated Positive Supply cr 4 ISO ISO GND | Is ra 39 2 fv: Ve | 5 29 2 | Bios Receiver #1 LED Driver 21. on_| Receiver #2 LED Driver | 2 a | Be Internal Connection. Leave this pin un- | Sk connected. Do not ground I 32 Ve Isolated Positive Supply | | 38 Ran | RS-232Receiver #2 Input | Isolated Ground | | tena Negative Supply Voltage | Internal Connection. Leave this pin unconnected. Do not ground | cScXVNMAX252 Complete, +5V-Powered, Isolated, Dual RS-232 Transceiver Module Isolation Applications The MAX252 is intended for industrial communications and control applications where voltage transients, differ- ential ground potentials or high noise may be encoun- tered. The MAX252A withstands 130Vrms (continuous), 1260Vams (1 min.) or 1520Vams (1 Sec.)}. For less strin- gent applications, the MAX252B is rated at 500Veams (1 min.) or 600Veams (1 sec.). For applications requiring higher isolation ratings or transmission rates greater than 9600 baud, Maxim recommends the MAX250 and MAX251 device set that uses external optocouplers and transformer. Figure 1 shows the typical interconnection for a complete 9600 bits/sec. transceiver. Important layout considera- tions include: * For maximum isolation, the isolation line through the center of Figure 1 should not be breached; connections from each side should be kept separate. * Optocoupler outputs (pins 18, 20, 24, and 26) are high-impedance nodes, so connecting traces should be + Rout 40] AC 02 (2 | 39) V- St] | 391 450 GND = p14 | [37\ V- Vee} 3 Mout Vv ~~ 5 {36} = T21 OR me at T2out T2IN a R1IN . Tine MAXIMA eon * > Ne} maxzs2 [3 4 _ Thun 3} | 32] V4 pe Fe ee <_ R2our aI | rol Ritpr R2| 7 i 12, | - a | pa} 120 RIDIN ia D7 TIDIN | | tory ti 1] LED COM cal p51 90 DET CON | | i Tap fit | pa, 2081 Poet | ES} RILED l: DET COM ay | 7 1S LED COM AoE fal | RAED | | = | wa ISOLATION BARRIER as short as possible to minimize stray capacitance and maximize data transfer rate; shunt capacitance seen by each pin should not exceed 10pF. The MAX252 pin out enables optimal printed circuit board layout by minimizing interconnect lengths and cross- overs. Figure 2 shows the preferred layout, which is strongly recommended for 9600 bits/sec. applications. Note the position of the ground traces, particularly the protection of pin 20 by the wraparound from pin 19. Isolation Example Figure 3 illustrates how to isolate an existing RS-232 interface by inserting a MAX252 and MAX233 in series Both devices invert while translating RS-232 to TTL and TTL to RS-232 levels. Since there is no net inversion, the circuit functions like two plain pieces of wire, but with 1520Vams (at 1 sec.) isolation between the ports. Detailed Description The MAX252 contains two integrated circuits, four op- tocouplers, four Capacitors, two diodes, and a small transformer. Together, these provide a complete, iso- lated, dual RS-232 transmitter and receiver. The non-iso- lated or logic side of the interface transfers logic signals to and from the optocouplers, while the isolated or cable side transfers data between the optocouplers and RS-232 TOP VIEW PIN 4 PIN 40 lol >>_-==>=_ = a SHDN (SO GND = 15V eo eo 0 a tH eo T2IN THIN ao GND oa R2oul oo PIN 21 PIN 20 Figure 1. Typical Interconnections 6 Figure 2. Preferred Layout MAXIMComplete, +5V-Powered, Isolated, Dual RS-232 Transceiver Module O Oo oOo | C bon pe-pe 2) 1S iso-pwr Pro 2|\$ ao] 0 | | | ars} 3 0 ty AT | cs}, | abe Tour 36 | bap O . | NN feo T200t} 3 | | | | G A A Se | Lr amor | | So | 26| | Le ce 28 Le anion = fa } * | Fi | | pe | pe | Figure 3. RS-232 Isolation Adapter from a Singte +5V Supply transmitters (line drivers) and receivers. The MAX252 also contains an isolation transformer and drive circuitry to supply power to the isolated side of the interface. On the logic side of the MAX252 are four identical non- inverting drivers whose outputs may be used either as optocoupler LED drivers or as TTL/CMOS logic outputs. Each driver input (T1in, T2in, Rtpin, R2oin) has a weak 4uA internal pull-up current source, and 0.5V hysteresis to improve noise rejection; logic thresholds for the driver inputs conform to standard TTL/CMOS specifications. The RS-232 side of the interface includes two line drivers and receivers along with circuitry to translate these levels to optocoupler signals. The RS-232 inputs (Rtn, R2in) and outputs (T1our, T2out) conform to EIA RS-232D and CCITT V.28 specifications. The inputs to the RS-232 line drivers (T1pin, T2pin), which are normally stragped to the internal optoisolators, are TTL/CMOS compatible. MAXLIM rl ' Vv ISOLATION BARRIER | Also included are an OUTPUT ENABLE control (EN) and a SHUTDOWN pin (SHON). EN places all driver outputs in a high-impedance state when driven high. SHDN, when pulled high, performs the following functions: 1) Turns off the 130kHz oscillator, removing power from the RS-232 side of the interface. 2) Places Tiour and T2our in a high-impedance state 3) Disables the 4uA pull-up currents at the logic-side river inputs (T1in, T2in, Rion, R2pin). 4) Resets logic-side driver outputs (T1Lpr, T2Lor, Rout, R2our) ta low. 5) Reduces power consumption to 50pnW. Module Product Reliability For reliability data on Maxim's Module Product Line, see Reliability Report RR-3A . cScXVNMAX252 Complete, +5V-Powered, Isolated, Dual RS-232 Transceiver Module MAX252 Block Diagram ___@- - AC a0 Be e | oF v 4 e e SEAT Vif. rap SHON | abet 3 I Ve $, (RULATOR ge C oy eT {ot Sys = | 4 | l Wo fee Tr A Ft | 8b 5{ GND ISO GNDI 1 V dog 9] | 2: F 4uA [- ' 8 4uA , reply TuoaF 55 1 yp ue THET 5 : pomp Mtn g > Tout > Ly LED COM FP" za ISO DET COM e <e an ss a N T2 7 T2 nN 8 nN lout aye T2LDR pay ort toe. [ee I > OUI Fs R1DET Rito 23} joa RILDR <J R1in 1] Ho : sper com , za + MZ ISOLED COM} oh va |__ pa R20 | PAD fof PLD <] en 3 Ee: | oe _ okey ae | Vy = | 7 | ISOLATION BARRIER 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. 8 Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 (408) 737-7600 1994 Maxim Integrated Products Printed USA MAXIM js a registered trademark of Maxim Integrated Products.