19-0333; Rev 0; 12/94 MAXIM 3.3V-Powered, 10Mbps and Slew-Rate-Limited True RS-485/RS-422 Transceivers General Description The MAX3483, MAX3485, MAX3486, MAX3488, MAX3490, and MAX3491 are 3.3V, low-power trans- ceivers for RS-485 and RS-422 communication, Each part contains one driver and one receiver. The MAX3483 and MAX3488 feature slew-rate-limited dri- vers that minimize EMI and reduce reflections caused by improperly terminated cables, allowing error-free data transmission at data rates up to 250kbps. The par- tially slew-rate-limited MAX3486 transmits up to 2.5Mbps. The MAX3485, MAX3490, and MAX3491 transmit at up to 1OMbps. Drivers are short-circuit current limited and are protect- ed against excessive power dissipation by thermal shutdown circuitry that places the driver outpufs into a high-impedance state. The receiver input has a fail-safe feature that guarantees a logic-high output if both inputs are open circuit. The MAX3488, MAX3490, and MAX3491 feature full- duplex communication, while the MAX3483, MAX3485, and MAX3486 are designed for half-duplex communi- cation. Applications Low-Power RS-485/RS-422 Transceivers Telecommunications Transceivers for EMl-Sensitive Applications Industrial-Contro! Local Area Networks Features @ Operate from a Single 3.3V Supply No Charge Pump! Interoperable with +5V Logic @ 8ns Max Skew (MAX3485/MAX3490/MAX3491) Slew-Rate Limited for Erroriess Data Transmission (MAX3483/MAX3488) @ 2nA Low-Current Shutdown Mode (MAX3483/MAX3485/MAX3486/MAX3491) -7V to +12V Common-Mode Input Voltage Range Allows up to 32 Transceivers on the Bus Full-Duplex and Half-Duplex Versions Available Industry Standard 75176 Pinout (MAX3483/MAX3485/MAX3486) @ Current-Limiting and Thermal Shutdown for Driver Overload Protection -?- Ordering Information PART TEMP. RANGE PIN-PACKAGE MAX3483CPA OC to +70C 8 Piastic DIP MAX3483CSA OC to +70C 8SO MAX3483C/D 0C to +70C Dice* MAX3483EPA -40C to +85C 8 Plastic DIP MAX3483ESA -40C to +85C 8SO0 MAX3485CPA OC to +70C 8 Plastic DIP MAX3485CSA OC to +70C 8SO MAX3485C/D OC to +70C Dice* MAX3485EPA -40C to +85C 8 Plastic DIP MAX3485ESA -40C to +85C 8S0 Ordering information continued at end of data sheet. * Contact factory for for dice specifications. Selection Table PART GUARANTEED SUPPLY HALF/FULL | SLEW-RATE DRIVER/ SHUTDOWN PIN NUMBER DATA RATE VOLTAGE DUPLEX LIMITED RECEIVER CURRENT COUNT (Mbps) (Vv) ENABLE (nA) MAX3483 0.25 Half Yes Yes 2 8 MAX3485 10 Half No Yes 2 8 MAX3486 25 Half Yes Yes 2 8 3.0 to 3.6 MAX3488 0.25 Full Yes No _ 8 MAX3490 10 Full No No _ 8 MAX3491 10 Full No Yes 2 14 MAAXISA Maxim Integrated Products 2-87 Cali toll free 1-800-998-8800 for free samples or literature. LEVEXVW/OGPEXVW/S8VEXVW/98VEXVW/SEVPEXUW/ESPEXUNMAX3483/MAX3485/MAX3486/MAX3488/MAX3490/MAX3491 3.3V-Powered, 10Mbps and Slew-Rate-Limited True RS-485/RS-422 Transceivers ABSOLUTE MAXIMUM RATINGS Supply Voltage (Vcc)... . Control Input Voltage (RE, DE)... Oriver Input Voltage (Dl).. Driver Output Voltage (A. B, -Y, a. Receiver Input Voltage (A, B)... Receiver Output Voltage (RO)... lee oe Continuous Power Dissipation (Ta = +70C) 8-Pin Plastic DIP (derate 9.09mW/'C above +70C).... 8-Pin SO (derate 5 BEMWP/PC above +70C). a. gay to (Vec + 0.3V) otters dV 14-Pin Plastic DIP (derate 10mW/C above +70C) ...... 800mWw ..-0.3V to 7V 14-Pin SO (derate 8.33mMW/C above +70C)......0....... .667mMW ..-0.3V to 7V Operating Temperature Ranges _-7.5V to 12.5V MAX34_ Cece eererieteeeneteteenes OC to +70C .7.5 to 12.5V MAX34_ Eo -40C to +85C 27mw 471mW Storage Temperature Range .... Lead Temperature (soldering, 40sec) Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not imped. Exposure to absolute maximum raling conditions for extended periods may affect device reliability. DC ELECTRICAL CHARACTERISTICS (Vcc = 3.3V 0.3V, Ta = TMIN to TMax, unless otherwise noted. Typical values are at Ta = +25C) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Ri = 100Q (RS-422), Figure 4 2.0 Differential Driver Output Voo RL = 549 (RS-485), Figure 4 15 v RL = 60Q (RS-485), Vcc = 3.3V, Figure 5 15 Change in Magnitude of Driver Differential Output Voltage for _ Compiementary Output States AVop | RL = 540 or 1002, Figure 4 0.2 Vv (Note 1) . Driver Common-Mode Output _ Voltage Voc Ri = 549 or 100, Figure 4 3 Vv Change in Magnitude of Common-Mode Output Voltage AVoc | Ry = 549 or 1000, Figure 4 0.2 Vv (Note 1) Input High Voltage ViH DE, Ol, RE 2.0 v Input Low Voltage Vit DE. DI, RE 0.8 v Logic Input Current lind DE, DI, RE +2 uA DE = OV, VIN = 12V 1.0 Input Current (A, B) lin2 Voc = OV or 3.6V Vin = 7V 08 mA DE = OV, RE = ov, Vout = 12V 20 Output Leakage (Y, 2) lo Voc = OV of 3.6V, MAX3491 | Voy7 = -7V 50 pA Output Leakage (Y, Z) | DE = OV, RE = Voc. Vout = 12V 1 A in Shutdown Mode Voc = OV or 3.6V, MAX3491[ Vout = -7V Z H Receiver Differential Threshald Voltage VrH | -?s Vom s 12V 0.2 0.2 Vv Receiver Input Hysteresis AVTH Vom = OV 50 mV Receiver Output High Voltage VOH lout = -1.5MA, Vip = 200mV, Figure 6 Voc - 0.4 Vv Receiver Output Low Voltage VoL lout = 2.5rnA, Vio = 200mvV, Figure 6 0.4 Vv Three-State (High Impedance) _ Output Current at Receiver loza | Voc = 3.6V, OV s Vout $ Vcc +1 yA Receiver Input Resistance Rin -7V < Vom s 12V 12 kQ 2-88 FIAAXIAA3.3V-Powered, 10Mbps and Slew-Rate-Limited True RS-485/RS-422 Transceivers DC ELECTRICAL CHARACTERISTICS (continued) (Voc = 3.3V +0.3V, Ta = Tain to Tmax, unless otherwise noted. Typical values are at Ta = +25C) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS DE = Vcc, 11 Supply Current lec No load, RE = OV or Voc mA DI = 0Ver Vcc DE = OV RE = ov 0.95 1.9 Supply Current in Shutdown Mode] !sHpN | DE = OV, RE = Vcc, Dl = Vcc or OV 0.002 1 yA Driver Short-Circuit Output | Vout = -7V -250 Current OSD Vout = 12V 250 ma ; OUT Rece ver Short-Circuit Outout losr OV <VRo < Voc +8 +60 mA DRIVER SWITCHING CHARACTERISTICSMAX3485, MAX3490, and MAX3491 (Vcc = 3.3V. Ta = +25C) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Driver Differential Output Delay top RL = 60Q, Figure 7 1 22 35 ns Driver Differential Output Transition Time tto Ri = 60Q, Figure 7 3 8 25 ns Driver Propagation Delay, Low-to-High Level tPLH Ri = 27Q, Figure 8 7 22 36 ns Driver Propagation Delay, High-to-Low Level {PHL Rt = 27Q, Figure 8 7 22 35 ns ItPLH - tpHil| Driver Propagation Delay Skew (Note 2) tpDs Ry. = 27Q, Figure 8 8 ns DRIVER OUTPUT ENABLE/DISABLE TIMES (MAX3485/MAX3491 only) Driver Output Enable Time to Low Level tpZL RL = 110Q, Figure 10 45 90 ns Driver Output Enable Time to High Level tPZH Ry = 110, Figure 9 45 90 ns Driver Output Disable Time from High Level tPHZ R_ = 110Q, Figure 9 40 80 ns Driver Output Disable Time from Low Level tPLz RL = 110Q, Figure 10 40 80 ns Driver Output Enable Time from Shutdown to Low Level test RL = 1109, Figure 10 650 900 ns Driver Output Enable Time from Shutdown to High Level tPSH Ri = 1108, Figure 9 650 900 ns DRIVER SWITCHING CHARACTERISTICSMAX3486 (Voc = 3.3V, Ta = +25C) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Driver Differential Output Delay top Ru = 60Q, Figure 7 24 48 70 ns Driver Differential Output Transition Time tip Ry = 60Q, Figure 7 15 35 60 ns Driver Propagation Delay, Low-ta-High Level tPLH RL = 27Q, Figure 8 20 48 70 ns Driver Propagation Delay, High-to-Low Level tPHL Ry, = 27Q, Figure 8 20 48 70 ns ItPLH - tpH_| Driver Propagation Delay Skew (Note 2) tpos Ry = 27Q, Figure 8 11 ns Driver Output Enable Time to Low Level tezt Ry = 1108, Figure 10 55 100 ns Driver Output Enable Time to High Level! tpzH | R_ = 1100, Figure 9 55 400 ns Driver Output Disable Time from High Level tpHz RL = 1102, Figure 9 45 80 ns Driver Output Disable Time from Low Level tPLz Ry. = 1108, Figure 10 45 80 ns Driver Output Enable Time from Shutdown to Low Level tes. RL = 110Q, Figure 10 700 4000 ns Driver Output Enable Time from Shutdown to High Level {PSH Ru = 1102, Figure 9 700 1000 ns MA AXIIA 2-89 LGVEXVIN/OGPEXVW/SSPEXVW/98VEXUW/SSPEXVW/ESrPEXUNMAX3483/MAX3485/MAX3486/MAX3488/MAX3490/MAX3491 3.3V-Powered, 10Mbps and Slew-Rate-Limited True RS-485/RS-422 Transceivers DRIVER SWITCHING CHARACTERISTICSMAX3483 and MAX3488_ (Vcc = 3.3V, Ta = +25C) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Driver Differential Output Delay too AL = 60, Figure 7 600 900 1400 ns Driver Differential Output Transition Time tto Ry = 602, Figure 7 400 700 1200 ns Driver Propagation Delay, Low-to-High Level tPLH RL = 27, Figure 8 700 1000 1500 ns Driver Propagation Delay, High-to-Low Level tPHL RL = 27Q, Figure 8 700 1000 1500 ns lteLH - pH! Driver Propagation Delay Skew (Note 2) tpps | Ri = 2782, Figure 8 100 ns DRIVER OUTPUT ENABLE/DISABLE TIMES (MAX3483 only) . Driver Output Enable Time to Low Level tpze RL = 110, Figure 10 900 1300 ns Driver Output Enable Time to High Level 1PZ2H RL = 1102, Figure 9 600 800 ns Driver Output Disable Time from High Level tPHZ Ri = 11022, Figure 9 50 80 ns Driver Output Disable Time from Low Level tpLz Ri = 1108, Figure 10 50 80 ns Driver Output Enable Time from Shutdown to Low Level tesi Re = 110Q, Figure 10 1.9 27 us Driver Output Enable Time from Shutdown to High Level tPSH Ri = 110Q, Figure 9 2.2 3.0 us RECEIVER SWITCHING CHARACTERISTICS (Voc = 3.3V, Ta = +25C) PARAMETER SYMBOL , CONDITIONS MIN TYP MAX UNITS Time to Shutdown 'SHON MAX3483/MAX3485/MAX3486/MAX3491 only 80 190 300 ns (Note 3) Receiver Propagation Delay, Vip = OV to 3.0V, Cy = 15pF, Figure 11 25 65 90 tAPLH ns Low-to-High Leve! MAX3483/MAX3488 25 75 120 Receiver Propagation Delay, | 1... Vip = OV to 3.0V, Ci = 15pF, Figure 14 25 65 90 ns High-to-Low Level | | MAX3483/MAXa488 25 75 120 ltpLH - tpHL! Receiver tRPDS Vip = OV to 3.0V, CL = 15pF, Figure 11 10 hs Propagation Delay Skew MAX3483/MAX3488 20 Receiver Output Enable Time Cy = 15pF, Figure 12, to Low Level 'PPZL | MAX3483/MAX3485/MAX3486/MAX3491 only 2 50 ns Receiver Output Enable Time Cy = 16pF, Figure 12, to High Level 'PRZH | MAx3483/MAX34B5/MAX3486/MAX3491 only 2 50 ns Receiver Output Disable Cy = 15pF, Figure 12, Time from High Level 'PRHZ | MAX3483/MAX3485/MAX3486/MAX3491 only 2 45 ns Receiver Output Disable ' Cy = 15pF, Figure 12, 25 45 ns Time from Low Level PRLZ | MAX3483/MAX3485/MAX3486/MAX3491 only Receiver Output Enable Time CL = 15pF, Figure 12, from Shutdown to Low Level | 'PRSL_ | MAx3483/MAX3485/MAX3486/MAX3491 only 720 1400 | ns Receiver Output Enable Time Cu = 15pF, Figure 12, 720 4400 ns from Shutdown to High Level | 'PRSH | mMAx3483/MAX3485/MAX3486/MAX349 1 only Note 1: AVop and AVoc are the changes in Vop and Voc. respectively, when the DI input changes state. Note 2: Measured on |tpLH () - tpi CY) and |tecy (Z) - teHe (Z)I. Note 3: The transceivers are put into shutdown by bringing RE high and DE low. If the inputs are in this state for less than 80ns, the parts are guaranteed not to enter shutdown. If the inputs are in this state for at least 300ns, the parts are guaranteed to have entered shutdown. See Low-Power Shutdown Mode section. 2-90 MAXLAA3.3V-Powered, 10Mbps and Slew-Rate-Limited True RS-485/RS-422 Transceivers Typical Operating Characteristics (Vcc = 3.3V, Ta = +25C, unless otherwise noted.) OUTPUT CURRENT vs. OUTPUT CURRENT vs. RECEIVER OUTPUT HIGH VOLTAGE RECEIVER OUTPUT LOW VOLTAGE RECEIVER OUTPUT HIGH VOLTAGE vs. TEMPERATURE Iro = 1 = =: = E . 4 <x = 5 - 2 oc > mw x 3 37 3 ond & = z 2 5 5 3 E a o 2 oO 0 05 10 15 20 25 30 35 0 05 10 15 20 25 30 35 40 -20 0 20 40 60 80 100 OUTPUT LOW VOLTAGE (V) OUTPUT HIGH VOLTAGE {V} TEMPERATURE (C) RECEIVER OUTPUT LOW VOLTAGE DRIVER OUTPUT CURRENT vs. ORIVER DIFFERENTIAL OUTPUT vs. TEMPERATURE DIFFERENTIAL OUTPUT VOLTAGE VOLTAGE vs. TEMPERATURE 08 Ino = 2.5mA 26 R=540 07 a = 25 - . aw Ss = 2 24 iy 06 a 23 = 5 > a 05 a & 22 S = & = 04 s 5 24 Ss cL Ss 5 03 z 2 2.0 & 5 Z 19 B02 5 2 ie 18 0.1 S17 0 0 16 40 -20 0 20 40 60 80 100 0 05 10 15 20 25 30 35 40 -20 0 20 40 60 80 100 TEMPERATURE (C) DIFFERENTIAL OUTPUT VOLTAGE (V) TEMPERATURE (C) OUTPUT CURRENT vs. OUTPUT CURRENT vs. DRIVER OUTPUT LOW VOLTAGE DRIVER OUTPUT HIGH VOLTAGE -80 = = E ke - a & -60 & = D> 2 oOo Oo 5 5 -40 a a 5 5 oO oO -20 0 0 2 4 #6 8 10 12 7654321012345 OUTPUT LOW VOLTAGE (V) OUTPUT HIGH VOLTAGE (V) MAXISA 2-91 LGPEXVW/OGPEXVIW/SSPEXVW/98PEXVW/SSPEXVWV/ESPEXUWNMAX3483/MAX3485/MAX3486/MAX3488/MAX3490/MAX3491 3.3V-Powered, 10Mbps and Slew-Rate-Limited True RS-485/RS-422 Transceivers Typical Operating Characteristics (continued) SUPPLY CURRENT SHUTDOWN CURRENT vs. TEMPERATURE vs. TEMPERATURE 1.2 100 X = DON'T CARE i 90 < Ww = 80 E & 70 e oc a & 1.0 DE =Vec, RE=X J g - 3 r] DE =0, RE =0 r z = 09 Se 40 & 5 30 a x 08 T~ * 20 10 07 | 0 40 -20 0 20 40 60 80 100 -40 -20 0 20 40 60 80 100 TEMPERATURE (C) TEMPERATURE (C) Pin Description PIN MAX3483/ NAME FUNCTION maxaaas; | WAnee | MAxa4a1 MAX3486 j 2 2 RO Receiver Output. If A > B by 200mV, RO will be high; if A < B by 200mvV, RO will be low. Receiver Output Enable. RO 1s enabled when RE is low; RO is high imped- 2 3 RE ance when RE is high. If RE is high and DE is low, the device will enter a low-power shutdown mode. Driver Output Enable. The driver outputs are enabled by bringing DE high. They are high impedance when DE is iow. If RE is high and DE is tow, the 3 a 4 DE device will enter a low-power shutdown mode. If the driver outputs are enabled, the parts function as line drivers. While they are high impedance, they function as line receivers if RE is low. 4 3 5 DI Driver Input. A low on Ol forces output Y low and output Z high. Similarly, a high on DI forces output Y high and output Z low. 5 4 6,7 GND Ground _ 5 9 Y Noninverting Driver Output _ 6 10 Z Inverting Driver Output 6 we _ A Noninverting Receiver Input and Noninverting Driver Output _ 8 12 A Noninverting Receiver Input 7 B inverting Receiver input and Inverting Driver Output 7 1 8B Inverting Receiver Input 8 1 13, 14 Vcc Positive Supply: 3.0V < Vcc < 3.6V 1.8 N.C No Connectnot internally connected 2-92 PAAXIIA3.3V-Powered, 10Mbps and Slew-Rate-Limited True RS-485/RS-422 Transceivers TOP VIEW [a | Veo na ot [3 +T6] A o [4 rs] GNo MAAXIAA MAX3483 MAX3485 MAX3466 ra | Vee | be es rs] GND RE i RO NOTE. PIN LABELS Y AND Z ON TIMING. TEST, AND WAVEFORM DIAGRAMS REFER 10 PINS A AND B WHEN DE IS HIGH Figure 1. MAX3483/MAX3485/MAX3486 Pin Configuration and Typical Operating Circuit TOP VIEW li MAXIAA MAX3488 Vec MAX3490 | vol] FQ as os |" no [2 | 748 o [3] 6] 2 , | [8A woe] tgs fs} 0 Lik OCLC 0 8 B DIP/SO 4] GND GNO Figure 2. MAX3488/MAX3490 Pin Configuration and Typical Operating Circuit TOP VIEW DE Ver ANAXIAA Vee RE Ja [13,14 MAX3491 Lo] e ~~ NC 1] 4] Veo 9 oY no [2 13} Veo o 0 VT Li 1 Ro re [3] 2] 4 z oe [4] hi] 8 alah ys ; (_ . DROOL Z SS eno [6] ray 5 eno [7] rajnec nc 18 | | DIP/SO 3] [67 RE GND GND DE Figure 3. MAX3491 Pin Configuration and Typical Operating Circuit MAXISA 2-93 LGVEXVIVOGPEXVW/S8PEXVAN/98SVEXVW/SEPEXUW/ESVEXUNMAX3483/MAX3485/MAX3486/MAX3488/MAX3490/MAX3491 3.3V-Powered, 10Mbps and Slew-Rate-Limited True RS-485/RS-422 Transceivers Voo AL Veo 2 =< s a |e 3752 Vem = -7V to +12V Vec Figure 4. Driver Vop and Voc Vou 1 if/E Figure 6. Receiver Voy and Vo, Figure 5. Driver Vop with Varying Common-Mode Voltage GENERATOR (NOTE 4) H = == -G = 1SpF (NOTE 5) 3V ov = 2.0V = -20V Figure 7. Driver Differential Output Delay and Transition Times 2-94 MAAXUMA3.3V-Powered, 10Mbps and Slew-Rate-Limited True RS-485/RS-422 Transceivers GENERATOR (NOTE 4} = 1.5V _ Vou + Voi Me? Y OUT Out Figure 8. Driver Propagation Times OV OR 3V out Ry = 11022 Cy = 50pF GENERATOR (NOTE 5) (NOTE 4) Von + Vou Vom = 2 = 15V QUT Vom 0.25V VoH ov Figure 9. Driver Enable and Disable Times (tpz, tpgy. tprz) Vcc R, = 1102 OUT C, = S09F (NOTE 5) T GENERATOR = (NOTE 4) 502 Figure 10. Driver Enable and Disable Times (tpz,, tps... tpiz) MAAXIZA 2-95 LGVEXVW/OGPEXVW/SSPEXVW/98SPEXVW/SSPEXUW/ESVEXUNMAX3483/MAX3485/MAX3486/MAX3488/MAX3490/MAX3491 3.3V-Powered, 10Mbps and Slew-Rate-Limited True RS-485/RS-422 Transceivers GENERATOR (NOTE 4) 6, = 150 (NOTE ) 15V Vee ov Figure 11. Receiver Propagation Delay 15V $3 oo tk Oo_ Vee -15V o Vip Cr = (NOTE 5) ~ GENERATOR (NOTE 4) 502 S1 OPEN $1 CLOSED $2 CLOSEO S2 OPEN 53 = 15V Sd =-15V av VV $1 OPEN $1 CLOSED IN 15V $2 CLOSED IN 1.5V S2 OPEN ov 3 = 1.5V ov $3 = -1.5V em] ft benz tpriz Vou _ _ _ V our ~ " OUT 0.25V ov Vow Figure 12. Receiver Enable and Disable Times Note 4: The input pulse is supplied by a generator with the following characteristics: PRR = 250kHz, 50% duty cycle, t, < 6.0ns, Zo = 50Q. Note 5: CL includes probe and stray capacitance 2-06 MAAXIAA3.3V-Powered, 10Mbps and Slew-Rate-Limited True RS-485/RS-422 Transceivers Function Tabies Devices with Receiver/Driver Enable (MAX3483/MAX3485/MAX3486/MAX3491) Table 1. Transmitting INPUTS OUTPUTS RE DE Di B* A* MODE x 1 1 0 1 Normal x 1 0 1 0 Normal 0 0 x High-Z High-Z Normal 1 0 xX High-Z High-Z Shutdown *Band A outputs are Z and Y, respectively, for full-duplex part (MAX349 1). X = Dont care; High-Z = High impedance Table 2. Receiving INPUTS OUTPUTS RE DE A,B RO MODE 0 or 24+0,2V 1 Normal 0 O $-0.2V 0 Normal 0 o* inputs Open 1 Normal 1 0 X High-Z Shutdown * DE is a don't care (x) for the full-duplex part (MAX3491). X = Don't care; High-Z = High impedance Devices without Receiver/Driver Enable (MAX3488/MAX3490) Table 3. Transmitting Table 4. Receiving INPUT OUTPUTS INPUTS OUTPUT DI Z Y A.B RO 1 0 1 2+0.2V 1 0 1 0 $-0.2V 0 Inputs Open 1 10d8/div OHz SCOkHZ/div Figure 13. Driver Output Waveform and FFT Plot of MAX3485/ MAX3490/MAX3491 Transmitting a 125kHz Signal MAAXIAN Applications Information The MAX3483/MAX3485/MAX3486/MAX3488/MAX3490/ MAX3491 are low-power transceivers for RS-485 and RS-422 communications. The MAX3483 and MAX3488 can transmit and receive at data rates up to 250kbps, the MAX3486 at up to 2.5Mbps, and the MAX3485/ MAX3490/MAX3491 at up to 10Mbps. The MAX3488/ MAX3490/MAX3491 are full-duplex transceivers, while. the MAX3483/MAX3485/MAX3486 are half-duplex. Driver Enable (DE) and Receiver Enable (RE) pins are included on the MAX3483/MAX3485/MAX3486/ MAX3491. When disabled, the driver and receiver out- puts are high impedance. Reduced EMI and Reflections (MAX3483/MAX3486/MAX3488) The MAX3483/MAX3488 are slew-rate limited, minimiz- ing EM! and reducing reflections caused by improperly terminated cables. Figure 13 shows both the driver output waveform of a MAX3485/MAX3490/MAX3491 transmitting a 125kHz signal and the Fourier analysis of that waveform. High-frequency harmonics with large amplitudes are evident. Figure 14 shows the same infor- mation, but for the slew-rate-limited MAX3483/MAX3488 transmitting the same signal. The high-frequency har- monics have much lower amplitudes, and the potential for EMI is significantly reduced. Low-Power Shutdown Mode (MAX3483/MAX3485/MAX3486/MAX3491) A low-power shutdown mode is initiated by bringing both RE high and DE tow. The devices will not shut down unless both the driver and receiver are disabled (high impedance). {n shutdown, the devices typically draw only 2nA of supply current. For these devices, the tpg and tps, enable times assume ithe part was in the low-powershutdown mode; the tpz4, and tpz, enable times assume the receiver or driver was disabled, but the part was not shut down. 10dB/div OHz SOOKH2/div Figure 14. Driver Output Waveform and FFT Plot of MAX3483/ MAX3488 Transmitting a 125kHz Signal 2-97 LEVEXVW/OGVEX VW/SSPEXVW/98PEXUW/SEVEXUW/ESPEXUWMAX3483/MAX3485/MAX3486/MAX3488/MAX3490/MAX3491 3.3V-Powered, 10Mbps and Slew-Rate-Limited True RS-485/RS-422 Transceivers ol 2Vidiv 2 Vidiv Widiv 20ns/div Widiv RO 2Vidiv 20ns/div Figure 15. MAX3485/MAX3490/MAX349 1 Driver Propagation Delay Figure 16. MAX3485/MAX3490/MAX3491 Receiver Propagation Delay Driven by External RS-485 Device Of 2V/div Zz Idi Y 1V/div tys/div lps/div Figure 17. MAX3483/MAX3488 Driver Propagation Delay Figure 18. MAX3483/MAX3488 Receiver Propagation Delay DI " 5V/div Vy-Vz 2Vidiv RO 5V/div 2us/div 0 5Vidiv Vy - Vz 2Vidiv RO SVidiv 2us/div Figure 19. MAX3483/MAX3488 System Differential Voltage at 125kHz Driving 4000 ft of Cable 2-98 Figure 20. MAX3485/MAX3490/MAX3491 System Differential Voltage at 125kHz Driving 4000 ft of Cable PMAAKUM3.3V-Powered, 10Mbps and Slew-Rate-Limited True RS-485/RS-422 Transceivers 1200 Dl MAAXIAN MAX3483 MAX3485 MAX3486 Dl DE RO RE DI DE RO RE Figure 21. MAX3483/MAX3485/MAX3486 Typical RS-485 Network Driver Output Protection Excessive output current and power dissipation caused by faults or by bus contention are prevented by two mechanisms. A foldback current limit on the output stage provides immediate protection against short circuits over the whole common-mode voltage range (see Typical Operating Characteristics). \n addition, a thermal shut- down circuit forces the driver outputs into a high-imped- ance state if the die temperature rises excessively. Propagation Delay Figures 15-18 show the typical propagation delays. Skew time is simply the difference between the low-to-high and high-to-low propagation delay. Small driver/receiver skew times help maintain a symmetrical mark-space ratio (50% duty cycle). The receiver skew time, |tprrH - teRH_|, is under 10ns (20ns for the MAX3483/MAX3488). The driver skew times are 8ns for the MAX3485/MAX3490/MAX3491, 1ins for the MAX3486, and typically under 100ns for the MAX3483/MAX3488. MAAXIMA Line Length vs. Data Rate The RS-485/RS-422 standard covers line lengths up to 4000 feet. For line lengths greater than 4000 feet, see Figure 23. Figures 19 and 20 show the system differential voltage for parts driving 4000 feet of 26AWG twisted-pair wire at 125kHz into 120Q toads. : Typical Applications The MAX3483, MAX3485, MAX3486, MAX3488, MAX3490, and MAX3491 transceivers are designed for bidirectional data communications on multipoint bus transmission lines. Figures 21 and 22 show typical net- work applications circuits. These parts can also be used as line repeaters, with cable lengths longer than 4000 feet, as shown in Figure 23. To minimize reflections, the line should be terminated at both ends in its characteristic impedance, and stub lengths off the main line should be kept as short as possible. The slew-rate-limited MAX3483/MAX3488 and the partially slew-rate-limited MAX3486 are more tolerant of imperfect termination. 2-99 LGVEXVW/OGPEXUW/S8PEXVW/9SVEXVW/SEPEXUW/ESPEXUNMAX3483/MAX3485/MAX3486/MAX3488/MAX3490/MAX3491 3.3V-Powered, 10Mbps and Slew-Rate-Limited True RS-485/RS-422 Transceivers AL ( no | R 1200 C RE B DE wel el on > A MAAXIIA MAX3468 MAX3490 MAX3491 oT TY Ol DE RERO NOTE: RE AND DE ON MAX3491 ONLY. Figure 22. MAX3488/MAX3490/MAX349 1 Fuil-Duplex RS-485 Network MAXIM MAX3488 MAX3490 MAX3491 as NOTE: RE AND DE ON MAX3491 ONLY. Rm (AS Figure 23. Line Repeater for MAX3488/MAX3490/MAX349 1 2-100 MAAXIAR3.3V-Powered, 10Mbps and Slew-Rate-Limited True RS-485/RS-422 Transceivers _Ordering Information (continued) Chip Topography PART TEMP. RANGE PIN-PACKAGE MAX3486CPA OC to +70C 8 Plastic DIP Fr MAX3486CSA OPC to +70C 8S0 ; MAX3486C/D OC to +70C Dice MAX3486EPA -40C to +85C 8 Plastic DIP RO MAX3486ESA -40C to +85C 8SO A MAX3488CPA OC to +70C 8 Plastic DIP AE MAX3488CSA OC to +70C 8SO B MAX3488C/D OC to +70C Dice* MAX3488EPA ~A0C to +85C 8 Plastic DIP 2/8 MAX3488ESA -40C to +85C 8sSO MAX3490CPA OC to +70C 8 Plastic DIP 0.146" MAX3490CSA OC to +70C 8SO (3.71mm) MAX3490C/D OC to +70C Dice* MAX3490EPA -40C to +B5C 8 Plastic DIP MAX3490ESA -40C to +85C 850 DE MAX3491CPD OC to +70C 14 Plastic DIP MAX3491CSD 0C to +70C 14S0 DI MAX3491C/D 0C to +70C Dice* Y/A MAX3491EPD -40C to +85C 14 Plastic DIP MAX3491ESD -40C to +85C 14S0 GND Vv * Contact factory for for dice specifications. 0,086" (2.18mm) TRANSISTOR COUNT: 810 SUBSTRATE CONNECTED TO GROUND MAAXLMA 2-101 LGVEXVIN/OGPEXVW/S8PEXVUW/9SPEXUW/SSPEXVW/ESVEXUW