19-2666; Rev 1; 12/05 15kV ESD-Protected, 60V Fault-Protected, 10Mbps, Fail-Safe RS-485/J1708 Transceivers The MAX3440E-MAX3444E fault-protected RS-485 and J1708 transceivers feature 60V protection from signal faults on communication bus lines. Each device contains one differential line driver with three-state output and one differential line receiver with three-state input. The 1/4-unitload receiver input impedance allows up to 128 transceivers on a single bus. The devices operate from a 5V supply at data rates of up to 10Mbps. True fail-safe inputs guarantee a logic-high receiver output when the receiver inputs are open, shorted, or connected to an idle data line. Hot-swap circuitry eliminates false transitions on the data bus during circuit initialization or connection to a live backplane. Short-circuit current-limiting and thermal shutdown circuitry protect the driver against excessive power dissipation, and on-chip 15kV ESD protection eliminates costly external protection devices. The MAX3440E-MAX3444E are available in 8-pin SO and PDIP packages and are specified over industrial and automotive temperature ranges. Applications RS-422/RS-485 Communications Truck and Trailer Applications Industrial Networks Telecommunications Systems Automotive Applications HVAC Controls Features 15kV ESD Protection 60V Fault Protection Guaranteed 10Mbps Data Rate (MAX3441E/MAX3443E) Hot Swappable for Telecom Applications True Fail-Safe Receiver Inputs Enhanced Slew-Rate-Limiting Facilitates Error-Free Data Transmission (MAX3440E/MAX3442E/MAX3444E) Allow Up to 128 Transceivers on the Bus -7V to +12V Common-Mode Input Range Automotive Temperature Range (-40C to +125C) Industry-Standard Pinout Ordering Information TEMP RANGE PIN-PACKAGE MAX3440EESA PART -40C to +85C 8 SO MAX3440EEPA -40C to +85C 8 PDIP MAX3440EASA -40C to +125C 8 SO MAX3440EAPA -40C to +125C 8 PDIP Ordering Information continued at end of data sheet. Selector Guide DATA RATE (Mbps) LOW-POWER SHUTDOWN RECEIVER/DRIVER ENABLE TRANSCEIVERS ON BUS HOT SWAP RS-485 0.25 No Yes 128 Yes RS-485 2.5 to 10 No Yes 128 Yes MAX3442E RS-485 0.25 Yes Yes 128 Yes MAX3443E RS-485 2.5 to 10 Yes Yes 128 Yes MAX3444E J1708 0.25 Yes Yes 128 Yes (only RE) PART TYPE MAX3440E MAX3441E Pin Configurations and Typical Operating Circuits TOP VIEW DE/RE FAULT 1 RO 2 R DE/RE 3 DI 4 D 8 VCC 7 B 6 A 5 GND FAULT 1 RO 2 DE/RE R 3 DI 4 D 8 VCC 7 B Rt 6 A 5 GND DIP/SO DIP/SO Pin Configurations and Typical Operating Circuits continued at end of data sheet. MAX3440E MAX3441E D DI B Rt A RO R FAULT ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com. 1 MAX3440E-MAX3444E General Description MAX3440E-MAX3444E 15kV ESD-Protected, 60V Fault-Protected, 10Mbps, Fail-Safe RS-485/J1708 Transceivers ABSOLUTE MAXIMUM RATINGS Voltages Referenced to GND VCC ........................................................................................+7V FAULT, DE/RE, RE, DE, DE, DI, TXD..........-0.3V to (VCC + 0.3V) A, B (Note 1) ........................................................................60V RO ..............................................................-0.3V to (VCC + 0.3V) Short-Circuit Duration (RO, A, B) ...............................Continuous Continuous Power Dissipation (TA = +70C) 8-Pin SO (derate 5.9mW/C above +70C)..................471mW 8-Pin PDIP (derate 9.09mW/C above +70C).............727mW Operating Temperature Ranges MAX344_EE_ _ ...............................................-40C to +85C MAX344_EA_ _ .............................................-40C to +125C Storage Temperature Range .............................-65C to +150C Junction Temperature ......................................................+150C Lead Temperature (soldering, 10s) .................................+300C Note 1: A, B must be terminated with 54 or 100 to guarantee 60V fault protection. 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 implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. DC ELECTRICAL CHARACTERISTICS (VCC = +4.75V to +5.25V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V and TA = +25C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS DRIVER Differential Driver Output Change in Magnitude of Differential Output Voltage Driver Common-Mode Output Voltage Change in Magnitude of Common-Mode Voltage VOD VOD VOC VOC Figure 1, RL = 100 2 VCC Figure 1, RL = 54 1.5 VCC Figure 1, RL = 100 or 54 (Note 2) Figure 1, RL = 100 or 54 VCC / 2 Figure 1, RL = 100 or 54 (Note 2) V 0.2 V 3 V 0.2 V DRIVER LOGIC Driver Input High Voltage VDIH Driver Input Low Voltage VDIL Driver Input Current IDIN Driver Short-Circuit Output Current (Note 3) IOSD Driver Short-Circuit Foldback Output Current IOSDF 2 V 0 VOUT +12V 0.8 V 2 A +350 -7V VOUT VCC -350 (VCC - 1V) VOUT +12V (Note 3) +25 -7V VOUT +1V (Note 3) -25 mA mA RECEIVER Input Current IA,B A, B VCC = GND, VA, B = 12V 250 VA, B = -7V -150 VA, B = 60V Receiver Differential Threshold Voltage Receiver Input Hysteresis 2 VTH VTH -7V VCM +12V -200 25 _______________________________________________________________________________________ A 6 mA -50 mV mV 15kV ESD-Protected, 60V Fault-Protected, 10Mbps, Fail-Safe RS-485/J1708 Transceivers MAX3440E-MAX3444E DC ELECTRICAL CHARACTERISTICS (continued) (VCC = +4.75V to +5.25V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V and TA = +25C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS RECEIVER LOGIC Output High Voltage VOH Figure 2, IOH = -1.6mA Output Low Voltage VOL Figure 2, IOL = 1mA VCC - 0.6 0.4 V V Three-State Output Current at Receiver IOZR 0 VA, B VCC 1 A Receiver Input Resistance RIN -7V VCM +12V Receiver Output Short-Circuit Current IOSR 0 VRO VCC VCIH DE, DE, RE, DE/RE 48 k 95 mA CONTROL Control Input High Voltage Input Current Latch During First Rising Edge IIN 2 DE, DE/RE, RE V 90 A SUPPLY CURRENT Normal Operation IQ Supply Current in Shutdown Mode Supply Current with Output Shorted to 60V ISHDN ISHRT No load, DI = VCC or GND MAX3440E (DE/RE = VCC), MAX3442E (DE = VCC, RE = GND), MAX3444E (DE = RE = GND) 30 MAX3441E (DE/RE = VCC), MAX3443E (DE = VCC, RE = GND) 10 mA DE = GND, RE = VCC (MAX3442E/ MAX3443E) 20 DE = GND, RE = VCC, TA = +25C (MAX3442E/MAX3443E) 10 DE = RE = VCC (MAX3444E) 100 DE = RE = VCC, TA = +25C (MAX3444E) 10 DE = GND, RE = GND, no load output in three-state (MAX3443E) 15 A mA PROTECTION SPECIFICATIONS (VCC = +4.75V to +5.25V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V and TA = +25C.) PARAMETER SYMBOL CONDITIONS MIN Overvoltage Protection A, B; RSOURCE = 0, RL = 54 60 ESD Protection A, B TYP MAX V 15 Human Body Model UNITS kV FAULT DETECTION Receiver Differential Threshold FDIPH VCM = 0, high limit 270 450 mV Receiver Differential Threshold FDIPL VCM = 0, low limit -450 -270 mV Fault-Detection Common-Mode Input Voltage Positive Fault-Detection Common-Mode Input Voltage Negative 12 V -7 V _______________________________________________________________________________________ 3 MAX3440E-MAX3444E 15kV ESD-Protected, 60V Fault-Protected, 10Mbps, Fail-Safe RS-485/J1708 Transceivers SWITCHING CHARACTERISTICS (MAX3440E/MAX3442E/MAX3444E) (VCC = +4.75V to +5.25V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V and TA = +25C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX3440E/MAX3442E, Figure 3, RL = 54, CL = 50pF Driver Propagation Delay tPLHA, tPLHB Driver Differential Propagation Delay tDPLH, tDPHL Figure 4, RL = 54, CL = 50pF Driver Differential Output Transition Time tLH,tHL Figure 4, RL = 54, CL = 50pF MAX UNITS 2000 ns 2000 ns 2000 ns MAX3444E, RDIFF = 60, CDIFF = 100pF 200 Driver Output Skew tSKEWAB, tSKEWBA RL = 54, CL = 50pF, tSKEWAB = |tPLHA - tPHLB|, tSKEWBA = |tPLHB - tPHLA| 350 ns Differential Driver Output Skew tDSKEW RL = 54, CL = 50pF, tDSKEW = |tDPLH - tDPHL| 200 ns Maximum Data Rate fMAX Driver Enable Time to Output High tPDZH Figure 5, RL = 500, CL = 50pF 2000 ns Driver Disable Time from Output High tPDHZ Figure 5, RL = 500, CL = 50pF 2000 ns tPDHS Figure 5, RL = 500, CL = 50pF (MAX3442E/MAX3444E) 4.2 s Driver Enable Time to Output Low tPDZL Figure 6, RL = 500, CL = 50pF 2000 ns Driver Disable Time from Output Low tPDLZ Figure 6, RL = 500, CL = 50pF 2000 ns Driver Enable Time from Shutdown to Output Low tPDLS Figure 6, RL = 500, CL = 50pF (MAX3442E/MAX3444E) 4.2 s Driver Time to Shutdown tSHDN RL = 500, CL = 50pF (MAX3442E/MAX3444E) 800 ns Receiver Propagation Delay tRPLH, tRPHL Figure 7, CL = 20pF, VID = 2V, VCM = 0 2000 ns Receiver Output Skew tRSKEW CL = 20pF, tRSKEW = |tRPLH - tRPHL| 200 ns Driver Enable Time from Shutdown to Output High 250 kbps Receiver Enable Time to Output High tRPZH Figure 8, RL = 1k, CL = 20pF 2000 ns Receiver Disable Time from Output High tRPHZ Figure 8, RL = 1k, CL = 20pF 2000 ns Receiver Wake Time from Shutdown tRPWAKE Figure 8, RL = 1k, CL = 20pF (MAX3442E/MAX3444E) 4.2 s Receiver Enable Time to Output Low tRPZL Figure 8, RL = 1k, CL = 20pF 2000 ns Receiver Disable Time from Output Low tRPLZ Figure 8, RL = 1k, CL = 20pF 2000 ns Receiver Time to Shutdown tSHDN RL = 500, CL= 50pF (MAX3442E/MAX3444E) 800 ns 4 _______________________________________________________________________________________ 15kV ESD-Protected, 60V Fault-Protected, 10Mbps, Fail-Safe RS-485/J1708 Transceivers (VCC = +4.75V to +5.25V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V and TA = +25C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Driver Propagation Delay tPLHA, tPLHB Figure 3, RL = 27, CL = 50pF 60 ns Driver Differential Propagation Delay tDPLH, tDPHL Figure 4, RL = 54, CL = 50pF 60 ns Driver Differential Output Transition Time tLH,tHL Figure 4, RL = 54, CL = 50pF 25 ns RL = 54, CL = 50pF, tSKEWAB = |tPLHA - tPHLB|, tSKEWBA = |tPLHB - tPHLA| 10 ns RL = 54, CL = 50pF, tDSKEW = |tDPLH - tDPHL| 10 ns tSKEWAB, tSKEWBA Driver Output Skew Differential Driver Output Skew tDSKEW Maximum Data Rate fMAX Driver Enable Time to Output High tPDZH Figure 5, RL = 500, CL = 50pF 1200 ns Driver Disable Time from Output High tPDHZ Figure 5, RL = 500, CL = 50pF 1200 ns Driver Enable Time from Shutdown to Output High tPDHS Figure 5, RL = 500, CL = 50pF (MAX3443E) 4.2 s Driver Enable Time to Output Low tPDZL Figure 6, RL = 500, CL = 50pF 1200 ns Driver Disable Time from Output Low tPDLZ Figure 6, RL = 500, CL = 50pF 1200 ns tPDLS Figure 6, RL = 500, CL = 50pF (MAX3443E) 4.2 s tSHDN Figure 6, RL = 500, CL = 50pF (MAX3443E) 800 ns Receiver Propagation Delay tRPLH, tRPHL Figure 7, CL = 20pF, VID = 2V, VCM = 0 85 ns Receiver Output Skew tRSKEW CL = 20pF, tRSKEW = |tRPLH - tRPHL| 15 ns Driver Enable Time from Shutdown to Output Low Driver Time to Shutdown 10 Mbps Receiver Enable Time to Output High tRPZH Figure 8, RL = 1k, CL = 20pF 400 ns Receiver Disable Time from Output High tRPHZ Figure 8, RL = 1k, CL = 20pF 400 ns Figure 8, RL = 1k, CL= 20pF (MAX3443E) 4.2 s Receiver Wake Time from Shutdown tRPWAKE Receiver Enable Wake Time from Shutdown tRPSH Figure 8, RL = 1k, CL = 20pF 400 ns Receiver Disable Time from Output Low tRPLZ Figure 8, RL = 1k, CL= 20pF 400 ns Receiver Time to Shutdown tSHDN RL = 500, CL= 50pF (MAX3443E) 800 ns Note 2: VOD and VOC are the changes in VOD and VOC, respectively, when the DI input changes state. Note 3: The short-circuit output current applies to peak current just before foldback current limiting; the short-circuit foldback output current applies during current limiting to allow a recovery from bus contention. _______________________________________________________________________________________ 5 MAX3440E-MAX3444E SWITCHING CHARACTERISTICS (MAX3441E/MAX3443E) Typical Operating Characteristics (VCC = +5V, TA = +25C, unless otherwise noted.) NO-LOAD SUPPLY CURRENT vs. TEMPERATURE DRIVER DISABLED, RECEIVER ENABLED 2 1 DRIVER AND RECEIVER ENABLED 16 12 DRIVER DISABLED, RECEIVER ENABLED 8 0.1 MAX3440E/MAX3442E/MAX3444E 0 MAX3442E/MAX3443E/MAX3444E 0 0.01 -40 -25 -10 5 20 35 50 65 80 95 110 125 -40 -25 -10 5 20 35 50 65 80 95 110 125 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (C) TEMPERATURE (C) TEMPERATURE (C) RECEIVER OUTPUT CURRENT vs. OUTPUT LOW VOLTAGE RECEIVER OUTPUT CURRENT vs. OUTPUT HIGH VOLTAGE RECEIVER OUTPUT VOLTAGE vs. TEMPERATURE 25 20 15 10 30 25 20 15 10 5 5 0 0 MAX3443E toc06 35 5.0 4.5 RECEIVER OUTPUT VOLTAGE (V) 30 MAX3443E toc05 35 40 RECEIVER OUTPUT CURRENT (mA) MAX3443E toc04 40 4.0 3.5 VOH, IOUT = +10mA 3.0 2.5 2.0 1.5 1.0 VOL, IOUT = -10mA 0.5 0 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 -40 -25 -10 5 20 35 50 65 80 95 110 125 OUTPUT LOW VOLTAGE (V) OUTPUT HIGH VOLTAGE (V) TEMPERATURE (C) DRIVER OUTPUT CURRENT vs. DIFFERENTIAL OUTPUT VOLTAGE DIFFERENTIAL OUTPUT VOLTAGE vs. TEMPERATURE 60 50 40 30 20 10 RL = 100 2.5 2.0 RL = 54 1.5 1.0 0.5 0.5 1.0 1.5 2.0 2.5 3.0 3.5 DIFFERENTIAL OUTPUT VOLTAGE (VA - VB) (V) 1200 RL = 54 800 400 0 -400 -800 -1600 DRIVER DISABLED, RECEIVER ENABLED -2000 0 0 1600 -1200 MAX3441E/MAX3443E 0 MAX3443E toc09 3.0 2000 A, B CURRENT (A) 70 3.5 A, B CURRENT vs. A, B VOLTAGE (TO GROUND) MAX3443E toc08 MAX3443E toc07 80 DIFFERENTIAL OUTPUT VOLTAGE (V) RECEIVER OUTPUT CURRENT (mA) 1 4 MAX3441E/MAX3443E 6 MAX3443E toc03 20 10 SUPPLY CURRENT (A) 4 3 24 SUPPLY CURRENT (mA) DRIVER AND RECEIVER ENABLED 5 SUPPLY CURRENT (mA) MAX3440E toc01 6 SHUTDOWN SUPPLY CURRENT vs. TEMPERATURE MAX3440E toc02 NO-LOAD SUPPLY CURRENT vs. TEMPERATURE DRIVER OUTPUT CURRENT (mA) MAX3440E-MAX3444E 15kV ESD-Protected, 60V Fault-Protected, 10Mbps, Fail-Safe RS-485/J1708 Transceivers -40 -25 -10 5 20 35 50 65 80 95 110 125 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 TEMPERATURE (C) A, B VOLTAGE (V) _______________________________________________________________________________________ 15kV ESD-Protected, 60V Fault-Protected, 10Mbps, Fail-Safe RS-485/J1708 Transceivers RL 2 A DI VOD D B RL VCC VOC 2 Figure 1. Driver VOD and VOC A VID RO R B 0 VOL VOH IOL (+) IOH (-) Figure 2. Receiver VOH and VOL 3V VOM DI A RL 2 S1 DI GENERATOR (NOTE 4) 0 tPLHA OUT D 1.5V 1.5V tPHLA VOH B 50 CL = 50pF (NOTE 5) VCC VOM = VOM A VOM VOL tPHLB VOH + VOL 1.5V 2 tPLHB VOH B VOM VOM VOL Figure 3. Driver Propagation Times 3V A DI D GENERATOR (NOTE 4) 0 RL B 1.5V 1.5V DI CL OUT tDPHL tDPLH 2.0V 50 90% VCC CL (A-B) 50% 10% 90% 50% 10% CL = 50pF (NOTE 5) tLH -2.0V tHL Figure 4. Driver Differential Output Delay and Transition Times _______________________________________________________________________________________ 7 MAX3440E-MAX3444E Test Circuits and Waveforms MAX3440E-MAX3444E 15kV ESD-Protected, 60V Fault-Protected, 10Mbps, Fail-Safe RS-485/J1708 Transceivers Test Circuits and Waveforms (continued) A DI 0 OR 3V 3V S1 A, B D B DE GENERATOR (NOTE 4) DE RL = 500W CL = 50pF (NOTE 5) 1.5V 1.5V tPDZH 0 tPDHS tPDHZ 50W VOH 0.25V A, B VOM = VOH + VOL 2 VOM 1.5V 0 Figure 5. Driver Enable and Disable Times VCC 3V A DI 0 OR 3V RL = 500 S1 D 1.5V 1.5V tPDZL DE A, B 0 tPDLS tPDLZ B DE GENERATOR (NOTE 4) CL = 50pF (NOTE 5) VCC A, B VOM 50 0.25V VOL Figure 6. Driver Enable and Disable Times 2.0V A GENERATOR (NOTE 4) VID 50 R B RO (A-B) 1.0V 1.0V CL = 20pF (NOTE 5) 0 tRPLH tRPHL VCC 1.0V RO VOM VOM 0 Figure 7. Receiver Propagation Delay 8 _______________________________________________________________________________________ 0 15kV ESD-Protected, 60V Fault-Protected, 10Mbps, Fail-Safe RS-485/J1708 Transceivers S1 S3 1.5V A -1.5V VID R RO VCC 1k S2 B CL = 20pF (NOTE 5) GENERATOR (NOTE 4) 50 3V RE 1.5V 0 tRPZH tRPSH tRPWAKE RO 3V S1 OPEN S2 CLOSED S3 = 1.5V RE 1.5V 0 tRPZL tRPSL VOH VCC RO 1.5V 1.5V 0 VOL 3V RE S1 CLOSED S2 OPEN S3 = -1.5V 1.5V 0 3V S1 OPEN S2 CLOSED S3 = 1.5V RE 1.5V 0 S1 CLOSED S2 OPEN S3 = -1.5V tRPHZ RO tRPLZ VOH 0.5V RO 0 VCC 0.5V VOL Figure 8. Receiver Enable and Disable Times Note 4: The input pulse is supplied by a generator with the following characteristics: f = 5MHz, 50% duty cycle; tr 6ns; Z0 = 50. Note 5: CL includes probe and stray capacitance. _______________________________________________________________________________________ 9 MAX3440E-MAX3444E Test Circuits and Waveforms (continued) 15kV ESD-Protected, 60V Fault-Protected, 10Mbps, Fail-Safe RS-485/J1708 Transceivers MAX3440E-MAX3444E Pin Description PIN MAX3440E MAX3441E 10 MAX3442E MAX3443E MAX3444E NAME FUNCTION 1 -- -- FAULT Fault output. 1 = fault; 0 = normal operation A or B under the following conditions: * A-B differential <200mV * A shorted to B * A shorted to a voltage within the common-mode range (detected only when the driver is enabled) * B shorted to a voltage within the common-mode range (detected only when the driver is enabled) * A or B outside the common-mode range 2 1 1 RO Receiver Output. If receiver enabled and (A-B) -50mV, RO = high; if (A-B) -200mV, RO = low. -- 2 2 RE Receiver Output Enable. Pull RE low to enable RO. -- -- 3 DE Driver Output Enable. Pull DE low to enable the outputs. Force DE high to three-state the outputs. Drive RE and DE high to enter low-power shutdown mode. 3 -- -- DE/RE Driver/Receiver Output Enable. Pull DE/RE low to threestate the driver output and enable RO. Force DE/RE high to enable driver output and three-state RO. -- 3 -- DE Driver Output Enable. Force DE high to enable driver. Pull DE low to three-state the driver output. Drive RE high and pull DE low to enter low-power shutdown mode. Driver Input. A logic low on DI forces the noninverting output low and the inverting output high. A logic high on DI forces the noninverting output high and the inverting output low. 4 4 -- DI -- -- 4 TXD 5 5 5 GND 6 6 6 A Noninverting Receiver Input/Driver Output 7 7 7 B Inverting Receiver Input/Driver Output 8 8 8 VCC J1708 Input. A logic low on TXD forces outputs A and B to the dominant state. A logic high on TXD forces outputs A and B to the recessive state. Ground Positive Supply, VCC = +4.75V to +5.25V ______________________________________________________________________________________ 15kV ESD-Protected, 60V Fault-Protected, 10Mbps, Fail-Safe RS-485/J1708 Transceivers Table 1. MAX3440E/MAX3441E Fault Table INPUTS A-B VID DIFFERENTIAL INPUT VOLTAGE OUTPUTS COMMON-MODE VOLTAGE RO FAULT CONDITIONED BY DELAY FAULT CONDITION 0.45V 1 0 Normal operation <0.45V and 0.27V 1 Indeterminate Indeterminate <0.27V and -0.05V 1 1 Low-input differential voltage -0.05V and -0.2V Indeterminate (Note 1) 1 Low-input differential voltage Low-input differential voltage 12V and -7V -0.2V and >-0.27V 0 1 -0.27V and >-0.45V 0 Indeterminate -0.45V 0 0 Indeterminate 1 X <-7V or >+12V Indeterminate Outside common-mode voltage range X = Don't care. Note 1: Receiver output may oscillate with this differential input condition. Table 3. MAX3442E/MAX3443E (RS-485/RS-422) Table 2. MAX3440E/MAX3441E (RS-485/RS-422) TRANSMITTING INPUTS TRANSMITTING INPUTS DE/RE A DE DI A B 0 0 X High-Z High-Z B 0 1 0 0 1 1 1 1 0 OUTPUTS DI OUTPUTS RE 0 X High-Z High-Z 0 1 0 0 1 1 0 X Shutdown Shutdown 1 1 1 0 1 1 0 0 1 1 1 1 1 0 X = Don't care. X = Don't care. Table 4. MAX3444E (J1708) Application Table 5. MAX3440E/MAX3441E (RS-485/RS-422) TRANSMITTING INPUTS OUTPUTS RECEIVING CONDITIONS INPUTS OUTPUTS TXD DE A B -- DE/RE (A - B) RO 0 1 High-Z High-Z -- 0 -0.05V 1 1 1 High-Z High-Z -- 0 -0.2V 0 0 0 0 1 Dominant state 0 Open/shorted 1 1 0 1 0 Recessive state 1 X High-Z X = Don't care. ______________________________________________________________________________________ 11 MAX3440E-MAX3444E Function Tables MAX3440E-MAX3444E 15kV ESD-Protected, 60V Fault-Protected, 10Mbps, Fail-Safe RS-485/J1708 Transceivers Function Tables (continued) Table 6. MAX3442E/MAX3443E (RS-485/RS-422) Table 7. MAX3444E (RS-485/RS-422) RECEIVING RECEIVING INPUTS INPUTS OUTPUTS OUTPUTS RE DE (A - B) RO RE DE (A - B) RO 0 X -0.05V 1 0 X -0.05V 1 0 X -0.2V 0 0 X -0.2V 0 0 X Open/shorted 1 0 X Open/shorted 1 1 1 X High-Z 1 0 X High-Z 1 0 X Shutdown 1 1 X Shutdown X = Don't care. X = Don't care. Detailed Description The MAX3440E-MAX3444E fault-protected transceivers for RS-485/RS-422 and J1708 communication contain one driver and one receiver. These devices feature failsafe circuitry, which guarantees a logic-high receiver output when the receiver inputs are open or shorted, or when they are connected to a terminated transmission line with all drivers disabled (see the True Fail-Safe section). All devices have a hot-swap input structure that prevents disturbances on the differential signal lines when a circuit board is plugged into a hot backplane (see the Hot-Swap Capability section). The MAX3440E/MAX3442E/MAX3444E feature a reduced slew-rate driver that minimizes EMI and reduces reflections caused by improperly terminated cables, allowing error-free data transmission up to 250kbps (see the Reduced EMI and Reflections section). The MAX3441E/ MAX3443E drivers are not slew-rate limited, allowing transmit speeds up to 10Mbps. Driver The driver accepts a single-ended, logic-level input (DI) and transfers it to a differential, RS-485/RS-422 level output (A and B). Deasserting the driver enable places the driver outputs (A and B) into a high-impedance state. Low-Power Shutdown (MAX3442E/MAX3443E/MAX3444E) The MAX3442E/MAX3443E/MAX3444E offer a low-power shutdown mode. Force DE low and RE high to shut down the MAX3442E/MAX3443E. Force DE and RE high to shut down the MAX3444E. A time delay of 50ns prevents the device from accidentally entering shutdown due to logic skews when switching between transmit and receive modes. Holding DE low and RE high for at least 800ns guarantees that the MAX3442E/MAX3443E enter shutdown. In shutdown, the devices consume a maximum 20A supply current. 60V Fault Protection The driver outputs/receiver inputs of RS-485 devices in industrial network applications often experience voltage faults resulting from shorts to the power grid that exceed the -7V to +12V range specified in the EIA/TIA485 standard. In these applications, ordinary RS-485 devices (typical absolute maximum -8V to +12.5V) require costly external protection devices. To reduce system complexity and eliminate this need for external protection, the driver outputs/receiver inputs of the MAX3440E-MAX3444E withstand voltage faults up to 60V with respect to ground without damage. Protection is guaranteed regardless whether the device is active, shut down, or without power. Receiver The receiver accepts a differential, RS-485/RS-422 level input (A and B), and transfers it to a single-ended, logic-level output (RO). Deasserting the receiver enable places the receiver inputs (A and B) into a high-impedance state (see Tables 1-7). 12 True Fail-Safe The MAX3440E-MAX3444E use a -50mV to -200mV differential input threshold to ensure true fail-safe receiver inputs. This threshold guarantees the receiver outputs a logic high for shorted, open, or idle data lines. The -50mV to -200mV threshold complies with the 200mV threshold EIA/TIA-485 standard. ______________________________________________________________________________________ 15kV ESD-Protected, 60V Fault-Protected, 10Mbps, Fail-Safe RS-485/J1708 Transceivers ESD Test Conditions ESD performance depends on a number of conditions. Contact Maxim for a reliability report that documents test setup, methodology, and results. RC 1M9 CHARGE-CURRENTLIMIT RESISTOR HIGHVOLTAGE DC SOURCE Cs 100pF RD 1.5k9 Human Body Model Figure 9a shows the Human Body Model, and Figure 9b shows the current waveform it generates when discharged into a low impedance. This model consists of a 100pF capacitor charged to the ESD voltage of interest, which is then discharged into the device through a 1.5k resistor. Driver Output Protection Two mechanisms prevent excessive output current and power dissipation caused by faults or bus contention. The first, a foldback current limit on the driver output stage, provides immediate protection against short circuits over the whole common-mode voltage range. The second, a thermal shutdown circuit, forces the driver outputs into a high-impedance state if the die temperature exceeds +160C. Normal operation resumes when the die temperature cools to +140C, resulting in a pulsed output during continuous short-circuit conditions. IP 100% 90% DISCHARGE RESISTANCE Ir PEAK-TO-PEAK RINGING (NOT DRAWN TO SCALE) AMPERES STORAGE CAPACITOR DEVICE UNDER TEST 36.8% 10% 0 0 Figure 9a. Human Body ESD Test Model tRL TIME tDL CURRENT WAVEFORM Figure 9b. Human Body Model Current Waveform ______________________________________________________________________________________ 13 MAX3440E-MAX3444E 15kV ESD Protection As with all Maxim devices, ESD-protection structures are incorporated on all pins to protect against ESD encountered during handling and assembly. The MAX3440E-MAX3444E receiver inputs/driver outputs (A, B) have extra protection against static electricity found in normal operation. Maxim's engineers have developed state-of-the-art structures to protect these pins against 15kV ESD without damage. After an ESD event, the MAX3440E-MAX3444E continue working without latchup. ESD protection can be tested in several ways. The receiver inputs are characterized for protection to 15kV using the Human Body Model. MAX3440E-MAX3444E 15kV ESD-Protected, 60V Fault-Protected, 10Mbps, Fail-Safe RS-485/J1708 Transceivers Hot-Swap Capability Hot-Swap Inputs Inserting circuit boards into a hot, or powered, backplane may cause voltage transients on DE, DE/RE, RE, and receiver inputs A and B that can lead to data errors. For example, upon initial circuit board insertion, the processor undergoes a power-up sequence. During this period, the high-impedance state of the output drivers makes them unable to drive the MAX3440E-MAX3444E enable inputs to a defined logic level. Meanwhile, leakage currents of up to 10A from the high-impedance output, or capacitively coupled noise from VCC or GND, could cause an input to drift to an incorrect logic state. To prevent such a condition from occurring, the MAX3440E-MAX3443E feature hot-swap input circuitry on DE, DE/RE, and RE to guard against unwanted driver activation during hot-swap situations. The MAX3444E has hot-swap input circuitry only on RE. When VCC rises, an internal pulldown (or pullup for RE) circuit holds DE low for at least 10s, and until the current into DE exceeds 200A. After the initial power-up sequence, the pulldown circuit becomes transparent, resetting the hot-swap tolerable input. Hot-Swap Input Circuitry At the driver-enable input (DE), there are two NMOS devices, M1 and M2 (Figure 10). When VCC ramps from zero, an internal 15s timer turns on M2 and sets the SR latch, which also turns on M1. Transistors M2, a 2mA current sink, and M1, a 100A current sink, pull DE to GND through a 5.6k resistor. M2 pulls DE to the disabled state against an external parasitic capacitance up to 100pF that may drive DE high. After 15s, the timer deactivates M2 while M1 remains on, holding DE low against three-state leakage currents that may drive DE high. M1 remains on until an external current source overcomes the required input current. At this time, the SR latch resets M1 and turns off. When M1 turns off, DE reverts to a standard, high-impedance CMOS input. Whenever VCC drops below 1V, the input is reset. A complementary circuit for RE uses two PMOS devices to pull RE to VCC. __________Applications Information 128 Transceivers on the Bus The MAX3440E-MAX3444E transceivers 1/4-unit-load receiver input impedance (48k) allows up to 128 transceivers connected in parallel on one communication line. Connect any combination of these devices, and/or other RS-485 devices, for a maximum of 32-unit loads to the line. Reduced EMI and Reflections The MAX3440E/MAX3442E/MAX3444E are slew-rate limited, minimizing EMI and reducing reflections caused by improperly terminated cables. Figure 11 shows the driver output waveform and its Fourier analysis of a 125kHz signal transmitted by a MAX3443E. High-frequency harmonic components with large amplitudes are evident. Figure 12 shows the same signal displayed for a MAX3442E transmitting under the same conditions. Figure 12's high-frequency harmonic components are much lower in amplitude, compared with Figure 11's, and the potential for EMI is significantly reduced. VCC 15s TIMER TIMER DE (HOT SWAP) 5.6k 100A M1 2mA M2 Figure 10. Simplified Structure of the Driver Enable Pin (DE) 14 ______________________________________________________________________________________ 15kV ESD-Protected, 60V Fault-Protected, 10Mbps, Fail-Safe RS-485/J1708 Transceivers where tRISE is the transmitter's rise time. For example, the MAX3442E's rise time is typically 800ns, which results in excellent waveforms with a stub length up to 53ft. A system can work well with longer unterminated stubs, even with severe reflections, if the waveform settles out before the UART samples them. RS-485 Applications The MAX3440E-MAX3443E transceivers provide bidirectional data communications on multipoint bus transmission lines. Figures 13 and 14 show a typical network applications circuit. The RS-485 standard covers line lengths up to 4000ft. To minimize reflections and reduce data errors, terminate the signal line at both ends in its characteristic impedance, and keep stub lengths off the main line as short as possible. 0 500kHz/div J1708 Applications The MAX3444E is designed for J1708 applications. To configure the MAX3444E, connect DE and RE to GND. Connect the signal to be transmitted to TXD. Terminate the bus with the load circuit as shown in Figure 15. The drivers used by SAE J1708 are used in a dominantmode application. DE is active low; a high input on DE places the outputs in high impedance. When the driver is disabled (TXD high or DE high), the bus is pulled high by external bias resistors R1 and R2. Therefore, a logic level high is encoded as recessive. When all transceivers are idle in this configuration, all receivers output logic high because of the pullup resistor on A and pulldown resistor on B. R1 and R2 provide the bias for the recessive state. C1 and C2 combine to form a 6MHz lowpass filter, effective for reducing FM interference. R2, C1, R4, and C2 combine to form a 1.6MHz lowpass filter, effective for reducing AM interference. Because the bus is unterminated, at high frequencies, R3 and R4 perform a pseudotermination. This makes the implementation more flexible, as no specific termination nodes are required at the ends of the bus. 20dB/div 20dB/div 2V/div 2V/div 5.00MHz Figure 11. Driver Output Waveform and FFT Plot of MAX3443E Transmitting a 125kHz Signal 0 500kHz/div 5.00MHz Figure 12. Driver Output Waveform and FFT Plot of MAX3442E Transmitting a 125kHz Signal ______________________________________________________________________________________ 15 MAX3440E-MAX3444E In general, a transmitter's rise time relates directly to the length of an unterminated stub, which can be driven with only minor waveform reflections. The following equation expresses this relationship conservatively: Length = tRISE / (10 x 1.5ns/ft) MAX3440E-MAX3444E 15kV ESD-Protected, 60V Fault-Protected, 10Mbps, Fail-Safe RS-485/J1708 Transceivers 120 120 DE/RE B B DI D D DI DE/RE A RO FAULT B A B A A RO R R FAULT R R D D MAX3440E MAX3441E DE/RE RO FAULT DI DI DE/RE RO FAULT Figure 13. MAX3440E/MAX3441E Typical RS-485 Network 120 120 DE B B DI D D DI DE RO A B A B A A R R R R D D MAX3442E MAX3443E DI DE RO RE DI DE RO RE Figure 14. MAX3442E/MAX3443E Typical RS-485 Network 16 RO RE RE ______________________________________________________________________________________ 15kV ESD-Protected, 60V Fault-Protected, 10Mbps, Fail-Safe RS-485/J1708 Transceivers TRANSISTOR COUNT: 310 PROCESS: BiCMOS DE Tx D TXD R1 4.7k R3 47 B C1 2.2nF MAX3444E A Rx R4 47 R2 4.7k R RO J1708 BUS C2 2.2nF RE VCC Figure 15. J1708 Application Circuit Pin Configurations and Typical Operating Circuits (continued) TOP VIEW DE RO 1 RE R 8 VCC RO 2 7 B RE 2 DE 3 6 A DE 3 5 GND DI 4 DI 4 D 1 DIP/SO R D 8 VCC 7 B Rt 6 A 5 GND MAX3442E MAX3443E D DI B Rt A RO R RE DIP/SO DE R 1 8 VCC RO RE 2 7 B RE 2 DE 3 6 A DE TXD 4 5 GND RO 1 D DIP/SO R 3 TXD 4 D DIP/SO MAX3444E 8 VCC 7 B Rt 6 A 5 GND D TXD B Rt A RO R RE ______________________________________________________________________________________ 17 MAX3440E-MAX3444E Chip Information MAX3440E-MAX3444E 15kV ESD-Protected, 60V Fault-Protected, 10Mbps, Fail-Safe RS-485/J1708 Transceivers Ordering Information (continued) PART TEMP RANGE PIN-PACKAGE MAX3441EESA -40C to +85C 8 SO MAX3441EEPA -40C to +85C 8 PDIP MAX3441EASA -40C to +125C 8 SO MAX3441EAPA -40C to +125C 8 PDIP MAX3442EESA -40C to +85C 8 SO MAX3442EEPA -40C to +85C 8 PDIP MAX3442EASA -40C to +125C 8 SO MAX3442EAPA -40C to +125C 8 PDIP MAX3443ECSA 0C to +70C 8 SO MAX3443ECPA 0C to +70C 8 PDIP MAX3443EESA -40C to +85C MAX3443EEPA -40C to +85C 8 PDIP MAX3443EASA -40C to +125C 8 SO 8 SO MAX3443EAPA -40C to +125C 8 PDIP MAX3444EESA -40C to +85C 8 SO MAX3444EEPA -40C to +85C 8 PDIP MAX3444EASA -40C to +125C 8 SO MAX3444EAPA -40C to +125C 8 PDIP 18 ______________________________________________________________________________________ 15kV ESD-Protected, 60V Fault-Protected, 10Mbps, Fail-Safe RS-485/J1708 Transceivers N E H INCHES MILLIMETERS MAX MIN 0.069 0.053 0.010 0.004 0.014 0.019 0.007 0.010 0.050 BSC 0.150 0.157 0.228 0.244 0.016 0.050 MAX MIN 1.35 1.75 0.10 0.25 0.35 0.49 0.25 0.19 1.27 BSC 3.80 4.00 5.80 6.20 0.40 SOICN .EPS DIM A A1 B C e E H L 1.27 VARIATIONS: 1 INCHES TOP VIEW DIM D D D MIN 0.189 0.337 0.386 MAX 0.197 0.344 0.394 MILLIMETERS MIN 4.80 8.55 9.80 MAX 5.00 8.75 10.00 N MS012 8 AA 14 AB 16 AC D A B e C 0-8 A1 L FRONT VIEW SIDE VIEW PROPRIETARY INFORMATION TITLE: PACKAGE OUTLINE, .150" SOIC APPROVAL DOCUMENT CONTROL NO. 21-0041 REV. B 1 ______________________________________________________________________________________ 1 19 MAX3440E-MAX3444E Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.) Package Information (continued) (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.) PDIPN.EPS MAX3440E-MAX3444E 15kV ESD-Protected, 60V Fault-Protected, 10Mbps, Fail-Safe RS-485/J1708 Transceivers ____________________Revision History Pages changed at Rev 1: 1, 6, 11 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. 20 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2005 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.