MAX13442E_11

19-3898; Rev 3; 3/11 ±15kV ESD-Protected, ±80V Fault-Protected, Fail-Safe RS-485/J1708 Transceivers General Description The MAX13442E/MAX13444E are fault-protected RS-485 and J1708 transceivers that feature ±80V protection from signal faults on communication bus lines. The MAX13442E/MAX13444E feature a reduced slew-rate driver that minimizes EMI and reflections, allowing error-free transmission up to 250kbps. The MAX13443E driver can transmit up to 10Mbps. The high-speed MAX13443E RS-485 tranceiver features ±60V protection from signal faults on communication bus lines. These transceivers feature foldback current limit. 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. 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 MAX13442E/MAX13443E/MAX13444E are available in an 8-pin SO package and are specified over the automotive temperature range. ♦ ±15kV ESD Protection ♦ ±80V Fault Protection (±60V MAX13443E) ♦ Guaranteed 10Mbps Data Rate (MAX13443E) ♦ Hot-Swappable for Telecom Applications ♦ True Fail-Safe Receiver Inputs ♦ Enhanced Slew-Rate-Limiting Facilitates Error-Free Data Transmission (MAX13442E/MAX13444E) ♦ Allow Up to 128 Transceivers on the Bus ♦ -7V to +12V Common-Mode Input Range ♦ ±6mA FoldBack Current Limit ♦ Industry-Standard Pinout Features MAX13442E/MAX13443E/MAX13444E Ordering Information PART MAX13442E ASA+ MAX13443E ASA+ MAX13444E ASA/V+T TEMP RANGE -40°C to +125°C -40°C to +125°C -40°C to +125°C PIN-PACKAGE 8 SO 8 SO 8 SO Applications RS-422/RS-485 Communications Truck and Trailer Applications Industrial Networks Telecommunications Systems Automotive Applications HVAC Controls +Denotes a lead(Pb)-free/RoHS-compliant package. /V denotes an automotive qualified part. T = Tape and reel. Selector Guide DATA RATE (Mbps) 0.25 10 0.25 FAULT PROTECTION (V) ±80 ±60 ±80 LOW-POWER RECEIVER/DRIVER SHUTDOWN ENABLE Yes Yes Yes Yes Yes Yes TRANSCEIVERS ON BUS 128 128 128 HOT SWAP Yes Yes Yes (only RE) PART MAX13442E MAX13443E MAX13444E TYPE RS-485 RS-485 J1708 Pin Configurations and Typical Operating Circuits TOP VIEW + RO RE 1 2 R 8 7 6 D 5 VCC B A GND RO 1 RE 2 DE DI 3 4 D DE + R 8 VCC 7B RT 6 A 5 GND MAX13442E MAX13443E B RT A R D DI DE 3 DI 4 RO RE SO SO Pin Configurations and Typical Operating Circuits continued at end of data sheet. ________________________________________________________________ Maxim Integrated Products 1 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. ±15kV ESD-Protected, ±80V Fault-Protected, Fail-Safe RS-485/J1708 Transceivers MAX13442E/MAX13443E/MAX13444E ABSOLUTE MAXIMUM RATINGS (Voltages referenced to GND.) VCC ........................................................................................+7V RE, DE, DE, DI, TXD ...................................-0.3V to (VCC + 0.3V) A, B (Note 1) (MAX13442E/MAX13444E) ............................±80V A, B (Note 1) (MAX13443E) .................................................±60V RO ..............................................................-0.3V to (VCC + 0.3V) Short-Circuit Duration (RO, A, B) ...............................Continuous Continuous Power Dissipation (TA = +70°C) SO (derate 7.6mW/°C above +70°C) ...........................606mW Operating Temperature Range .........................-40°C to +125°C Storage Temperature Range .............................-65°C to +150°C Junction Temperature ......................................................+150°C Lead Temperature (soldering, 10s) .................................+300°C Soldering Temperature (reflow) .......................................+260°C Note 1: During normal operation, a termination resistor must be connected between A and B in order to guarantee overvoltage protection up to the absolute maximum rating of this device. When not in operation, these devices can withstand fault voltages up to the maximum rating without a termination resistor and will not be damaged. 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. PACKAGE THERMAL CHARACTERISTICS (Note 2) SO Junction-to-Ambient Thermal Resistance (θJA) .........132°C/W Junction-to-Case Thermal Resistance (θJC) ................38°C/W Note 2: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a fourlayer board. For detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial. DC ELECTRICAL CHARACTERISTICS (VCC = +4.75V to +5.25V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V and TA = +25°C.) PARAMETER DRIVER Differential Driver Output Change in Magnitude of Differential Output Voltage Driver Common-Mode Output Voltage Change in Magnitude of Common-Mode Voltage DRIVER LOGIC Driver-Input High Voltage Driver-Input Low Voltage Driver-Input Current Driver Short-Circuit Output Current (Note 4) Driver Short-Circuit Foldback Output Current Driver-Limit Short-Circuit Foldback Output Current VDIH VDIL IDIN I OSD I OSDF I OSDL 0V -7V -7V VOUT VOUT VOUT VOUT VOUT +12V VCC VOUT +12V (Note 4) +1V (Note 4) +6 -6 -350 +25 -25 2 0.8 ±2 +350 V V μA mA mA mA VOD VOD VOC VOC F igure 1, RL = 1 00 F igure 1, RL = 5 4 F igure 1, RL = 1 00 F igure 1, RL = 1 00 or 54 or 54 (Note 3) VCC / 2 2 1.5 VCC VCC 0.2 3 0.2 V V V V SYMBOL CONDITIONS MIN TYP MAX UNITS F igure 1, RL = 1 00 or 54 (Note 3) (MAX13442E/MAX13443E) (VCC - 1V) + 20V, RL = 1 00 -15V, RL = 100 2 _______________________________________________________________________________________ ±15kV ESD-Protected, ±80V Fault-Protected, Fail-Safe RS-485/J1708 Transceivers MAX13442E/MAX13443E/MAX13444E 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 = +25°C.) PARAMETER R ECEIVER Input Current Receiver-Differential Threshold Voltage Receiver-Input Hysteresis R ECEIVER LOGIC Output-High Voltage Output-Low Voltage Three-State Output Current at Receiver Receiver Input Resistance Receiver Output Short-Circuit Current CONTROL Control-Input High Voltage Input-Current Latch During First Rising Edge SUPPLY CURRENT DE = VCC, RE = GND (MAX13442E) No load, (DE = RE = GND) (MAX13444E) DI = VCC (DE = VCC, RE = GND) or GND (MAX13443E) DE = GND, RE = VCC (MAX13442E/MAX13443E) Supply Current in Shutdown Mode I SHDN DE = GND, RE = VCC, TA = + 25°C (MAX13442E/MAX13443E) DE = RE = VCC (MAX13444E) DE = RE = VCC, TA = +25°C (MAX13444E) Supply Current with Output Shorted to ± 60V I SHRT DE = GND, RE = GND, no load output in three-state (MAX13443E) 30 mA 10 20 μA VCIH I IN DE, DE, RE DE, RE 2 90 V μA VOH VOL I OZR RIN I OSR F igure 2, I OH = -1.6mA F igure 2, I OL = 1 mA 0V -7V 0V VA, B VCM VRO VCC +12V VCC 48 ±95 VCC - 0.6 0.4 ±1 V V μA k mA IA,B A, B receive mode -7V VCM VCC = GND, VA, B = 1 2V VA, B = -7V VA, B = ± 80V +12V -200 25 250 -150 ±6 -50 μA mA mV mV SYMBOL CONDITIONS MIN TYP MAX UNITS VTH VTH Normal Operation ICC 10 100 10 ±15 mA _______________________________________________________________________________________ 3 ±15kV ESD-Protected, ±80V Fault-Protected, Fail-Safe RS-485/J1708 Transceivers MAX13442E/MAX13443E/MAX13444E PROTECTION SPECIFICATIONS (VCC = +4.75V to +5.25V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V and TA = +25°C.) PARAMETER Overvoltage Protection ESD Protection SYMBOL CONDITIONS A, B; RSOURCE = 0 , RL = 5 4 A, B MAX13442E/ MAX13444E MAX13443E MIN ±80 ±60 ±15 kV TYP MAX UNITS V Human Body Model SWITCHING CHARACTERISTICS (MAX13442E/MAX13444E) (VCC = +4.75V to +5.25V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V and TA = +25°C.) PARAMETER Driver Propagation Delay Driver Differential Propagation Delay Driver Differential Output Transition Time Driver Output Skew SYMBOL tPLHA, tPLHB tDPLH, tDPHL tLH,tHL tSKEWAB, tSKEWBA tDSKEW fMAX tPDZH tPDHZ tPDHS tPDZL tPDLZ tPDLS tSHDN tRPLH, tRPHL tRSKEW tRPZH tRPHZ tRPWAKE tRPZL tRPLZ tSHDN RL = 500Ω, CL = 50pF, Figure 5 RL = 500Ω, CL = 50pF, Figure 5 RL = 500Ω, CL = 50pF, Figure 5 RL = 500Ω, CL = 50pF, Figure 6 RL = 500Ω, CL = 50pF, Figure 6 RL = 500Ω, CL = 50pF, Figure 6 RL = 500Ω, CL = 50pF CL = 20pF, VID = 2V, VCM = 0V, Figure 7 CL = 20pF, tRSKEW = |tRPLH - tRPHL| RL = 1kΩ, CL = 20pF, Figure 8 RL = 1kΩ, CL = 20pF, Figure 8 RL = 1kΩ, CL = 20pF, Figure 8 RL = 1kΩ, CL = 20pF, Figure 8 RL = 1kΩ, CL = 20pF, Figure 8 RL = 500Ω, CL = 50pF CONDITIONS Figure 3, RL = 54Ω, CL = 50pF (MAX13442E) RDIFF = 60Ω, CDIFF = 100pF (MAX13444E) RL = 54Ω, CL = 50pF, Figure 4 RL = 54Ω, CL = 50pF, Figure 4 RL = 54Ω, CL = 50pF, tSKEWAB = |tPLHA - tPHLB|, tSKEWBA = |tPLHB - tPHLA| RL = 54Ω, CL = 50pF, tDSKEW = |tDPLH - tDPHL| 250 2000 2000 4.2 2000 2000 4.2 800 2000 200 2000 2000 4.2 2000 2000 800 200 MIN TYP MAX 2000 2000 2000 UNITS ns ns ns 350 ns Differential Driver Output Skew Maximum Data Rate Driver Enable Time to Output High Driver Disable Time from Output High Driver Enable Time from Shutdown to Output High Driver Enable Time to Output Low Driver Disable Time from Output Low Driver Enable Time from Shutdown to Output Low Driver Time to Shutdown Receiver Propagation Delay Receiver Output Skew Receiver Enable Time to Output High Receiver Disable Time from Output High Receiver Wake Time from Shutdown Receiver Enable Time to Output Low Receiver Disable Time from Output Low Receiver Time to Shutdown 200 ns kbps ns ns µs ns ns µs ns ns ns ns ns µs ns ns ns 4 _______________________________________________________________________________________ ±15kV ESD-Protected, ±80V Fault-Protected, Fail-Safe RS-485/J1708 Transceivers SWITCHING CHARACTERISTICS (MAX13443E) (VCC = +4.75V to +5.25V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V and TA = +25°C.) PARAMETER Driver Propagation Delay Driver Differential Propagation Delay Driver Differential Output Transition Time Driver Output Skew SYMBOL tPLHA, tPLHB tDPLH, tDPHL tLH,tHL tSKEWAB, tSKEWBA tDSKEW fMAX tPDZH tPDHZ tPDHS tPDZL tPDLZ tPDLS tSHDN tRPLH, tRPHL tRSKEW tRPZH tRPHZ tRPWAKE tRPSH tRPLZ tSHDN RL = 500Ω, CL = 50pF, Figure 5 RL = 500Ω, CL = 50pF, Figure 5 RL = 500Ω, CL = 50pF, Figure 5 RL = 500Ω, CL = 50pF, Figure 6 RL = 500Ω, CL = 50pF, Figure 6 RL = 500Ω, CL = 50pF, Figure 6 RL = 500Ω, CL = 50pF, Figure 6 CL = 20pF, VID = 2V, VCM = 0V, Figure 7 CL = 20pF, tRSKEW = |tRPLH - tRPHL| RL = 1kΩ, CL = 20pF, Figure 8 RL = 1kΩ, CL = 20pF, Figure 8 RL = 1kΩ, CL = 20pF, Figure 8 RL = 1kΩ, CL = 20pF, Figure 8 RL = 1kΩ, CL = 20pF, Figure 8 RL = 500Ω, CL = 50pF CONDITIONS RL = 27Ω, CL = 50pF, Figure 3 RL = 54Ω, CL = 50pF, Figure 4 RL = 54Ω, CL = 50pF, Figure 4 RL = 54Ω, CL = 50pF, tSKEWAB = |tPLHA - tPHLB|, tSKEWBA = |tPLHB - tPHLA| RL = 54Ω, CL = 50pF, tDSKEW = |tDPLH - tDPHL| 10 1200 1200 4.2 1200 1200 4.2 800 85 15 400 400 4.2 400 400 800 MIN TYP MAX 60 60 25 UNITS ns ns ns MAX13442E/MAX13443E/MAX13444E 10 ns Differential Driver Output Skew Maximum Data Rate Driver Enable Time to Output High Driver Disable Time from Output High Driver Enable Time from Shutdown to Output High Driver Enable Time to Output Low Driver Disable Time from Output Low Driver Enable Time from Shutdown to Output Low Driver Time to Shutdown Receiver Propagation Delay Receiver Output Skew Receiver Enable Time to Output High Receiver Disable Time from Output High Receiver Wake Time from Shutdown Receiver Enable Wake Time from Shutdown Receiver Disable Time from Output Low Receiver Time to Shutdown 10 ns Mbps ns ns µs ns ns µs ns ns ns ns ns µs ns ns ns Note 3: ΔVOD and ΔVOC are the changes in VOD and VOC, respectively, when the DI input changes state. Note 4: 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 ±15kV ESD-Protected, ±80V Fault-Protected, Fail-Safe RS-485/J1708 Transceivers MAX13442E/MAX13443E/MAX13444E Typical Operating Characteristics (VCC = +5V, TA = +25°C, unless otherwise noted.) NO-LOAD SUPPLY CURRENT vs. TEMPERATURE MAX13442-4E toc01 NO-LOAD SUPPLY CURRENT vs. TEMPERATURE MAX13442-4E toc02 SHUTDOWN SUPPLY CURRENT vs. TEMPERATURE MAX13442E DI = DE = GND RE = VCC MAX13442-4E toc03 6 5 SUPPLY CURRENT (mA) 4 3 2 1 MAX13443E 0 DRIVER DISABLED, RECEIVER ENABLED DRIVER AND RECEIVER ENABLED 24 20 SUPPLY CURRENT (mA) 16 12 8 4 0 DRIVER DISABLED, RECEIVER ENABLED MAX13442E/MAX13444E DRIVER AND RECEIVER ENABLED 10 SHUTDOWN SUPPLY CURRENT (μA) 1 0.1 0.01 0.001 0.0001 0.00001 0.000001 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) -40 -20 0 20 40 60 80 100 120 TEMPERATURE (°C) -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) RECEIVER OUTPUT CURRENT vs. OUTPUT-LOW VOLTAGE MAX13442-4E toc04 RECEIVER OUTPUT CURRENT vs. OUTPUT-HIGH VOLTAGE 35 30 25 20 15 10 5 0 MAX13442-4E toc05 40 RECEIVER OUTPUT CURRENT (mA) 35 30 25 20 15 10 5 0 0 40 RECEIVER OUTPUT CURRENT (mA) 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 OUTPUT LOW VOLTAGE (V) 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 OUTPUT LOW VOLTAGE (V) RECEIVER OUTPUT VOLTAGE vs. TEMPERATURE MAX13442-4E toc06 DRIVER OUTPUT CURRENT vs. DIFFERENTIAL OUTPUT VOLTAGE 140 DRIVER OUTPUT CURRENT (mA) 120 100 80 60 40 20 0 RL = 54Ω MAX13442E DI = GND, DE = VCC, VOLTAGE APPLIED TO OUTPUT A MAX13442-4E toc07 5.0 4.5 RECEIVER OUTPUT VOLTAGE (V) 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 VOL, IOUT = -10mA VOH, IOUT = 10mA -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) 10 20 30 40 50 60 70 80 DIFFERENTIAL OUTPUT VOLTAGE (V) 6 _______________________________________________________________________________________ ±15kV ESD-Protected, ±80V Fault-Protected, Fail-Safe RS-485/J1708 Transceivers Typical Operating Characteristics (continued) (VCC = +5V, TA = +25°C, unless otherwise noted.) DRIVER OUTPUT CURRENT vs. DIFFERENTIAL OUTPUT VOLTAGE DIFFERENTIAL OUTPUT VOLTAGE (V) 90 DRIVER OUTPUT CURRENT (mA) 80 70 60 50 40 30 20 10 0 -80 -65 -50 -35 -20 -5 DIFFERENTIAL OUTPUT VOLTAGE (V) RL = 54Ω MAX13442E DI = GND, DE = VCC, VOLTAGE APPLIED TO OUTPUT B MAX13442-4E toc08 MAX13442E/MAX13443E/MAX13444E DIFFERENTIAL OUTPUT VOLTAGE vs. TEMPERATURE MAX13442-4E toc09 100 3.5 3.0 RL = 100Ω 2.5 2.0 1.5 1.0 0.5 MAX13442E 0 RL = 54Ω -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) DIFFERENTIAL OUTPUT VOLTAGE vs. TEMPERATURE MAX13442-4E toc10 A, B CURRENT vs. A, B VOLTAGE (TO GROUND) 3200 2800 2400 2000 1600 1200 800 400 0 -400 -800 -1200 -1600 -2000 DRIVER DISABLED, RECEIVER ENABLED MAX13442-4E toc11 3.5 DIFFERENTIAL OUTPUT VOLTAGE (V) 3.0 2.5 2.0 1.5 1.0 0.5 MAX13443E 0 RL = 54Ω RL = 100Ω A, B CURRENT (μA) NO LOAD RL = 54Ω MAX13442E -80 -60 -40 -20 0 20 40 60 80 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) A, B VOLTAGE (V) A, B CURRENT vs. A, B VOLTAGE (TO GROUND) 1600 1200 A, B CURRENT (μA) 800 400 0 -400 -800 -1200 -1600 -2000 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 A, B VOLTAGE (V) MAX13443E RL = 54Ω NO LOAD DRIVER DISABLED, RECEIVER ENABLED MAX13442-4E toc12 2000 _______________________________________________________________________________________ 7 ±15kV ESD-Protected, ±80V Fault-Protected, Fail-Safe RS-485/J1708 Transceivers MAX13442E/MAX13443E/MAX13444E Test Circuits and Waveforms RL A DI D B VCC VOD RL 2 2 VOC Figure 1. Driver VOD and VOC A VID B 0 VOL IOL (+) VOH IOH (-) R RO Figure 2. Receiver VOH and VOL 3V VOM DI A DI D GENERATOR (NOTE 5) 50Ω VCC VOH + VOL ≈ 1.5V 2 B B CL = 50pF (NOTE 6) A RL 2 1.5V 1.5V 0V S1 OUT tPLHA tPHLA VOH VOM VOM VOL tPHLB tPLHB VOH VOM VOM VOL VOM = Figure 3. Driver Propagation Times 3V DI RL OUT 1.5V 1.5V 0V tDPLH tDPHL ≈ 2.0V 50% 10% tHL DI D GENERATOR (NOTE 5) A CL B 50Ω VCC CL 90% (A–B) CL = 50pF (NOTE 6) tLH 50% 10% 90% ≈ -2.0V Figure 4. Driver Differential Output Delay and Transition Times 8 _______________________________________________________________________________________ ±15kV ESD-Protected, ±80V Fault-Protected, Fail-Safe RS-485/J1708 Transceivers Test Circuits and Waveforms (continued) MAX13442E/MAX13443E/MAX13444E A DI 0 OR 3V D B DE GENERATOR (NOTE 5) 50Ω S1 A, B RL = 500Ω DE 1.5V tPDZH tPDHS 1.5V 3V 0V tPDHZ VOH CL = 50pF (NOTE 6) 0.25V A, B VOM = VOH + VOL ≈ 1.5V 2 VOM 0V Figure 5. Driver Enable and Disable Times VCC 3V A DI 0 OR 3V D B DE GENERATOR (NOTE 5) 50Ω CL = 50pF (NOTE 6) A, B VOM 0.25V VOL VCC S1 RL = 500Ω A, B DE 1.5V tPDZL tPDLS 1.5V 0V tPDLZ Figure 6. Driver Enable and Disable Times A GENERATOR (NOTE 5) VID 50Ω B R RO CL = 20pF (NOTE 6) tRPLH tRPHL (A–B) 1.0V 1.0V 2.0V 0V VCC 1.0V 0V RO VOM VOM 0V Figure 7. Receiver Propagation Delay _______________________________________________________________________________________ 9 ±15kV ESD-Protected, ±80V Fault-Protected, Fail-Safe RS-485/J1708 Transceivers MAX13442E/MAX13443E/MAX13444E Test Circuits and Waveforms (continued) +1.5V -1.5V S3 VID B CL = 20pF (NOTE 6) GENERATOR (NOTE 5) 50Ω S1 A R RO 1kΩ S2 VCC 3V RE tRPZH tRPSH tRPWAKE RO 1.5V 0V 3V RE 1.5V 0V tRPHZ RO 0.5V VOH RO 0V S1 OPEN S2 CLOSED VS3 = 1.5V RE 1.5V 1.5V 0V S1 OPEN S2 CLOSED VS3 = 1.5V RE tRPZL tRPSL VOH RO 1.5V 1.5V 3V S1 CLOSED S2 OPEN VS3 = -1.5V 0V VCC VOL 3V S1 CLOSED S2 OPEN VS3 = -1.5V 0V tRPLZ 0.5V VCC VOL Figure 8. Receiver Enable and Disable Times Note 5: The input pulse is supplied by a generator with the following characteristics: f = 5MHz, 50% duty cycle; tr ≤ 6ns; Z0 = 50Ω. Note 6: CL includes probe and stray capacitance. 10 ______________________________________________________________________________________ ±15kV ESD-Protected, ±80V Fault-Protected, Fail-Safe RS-485/J1708 Transceivers Pin Description PIN MAX13442E MAX13443E 1 2 3 MAX13444E 1 2 — NAME FUNCTION Receiver Output. If the receiver is enabled and (VA - VB) RO = high; if (VA - VB) -200mV, RO = low. Receiver Output Enable. Pull RE low to enable RO. Driver Output Enable. Force DE high to enable driver. Pull DE low to three-state the driver output. Drive RE h igh 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. Ground Noninverting Receiver Input/Driver Output Inverting Receiver Input/Driver Output Positive Supply, VCC = +4.75V to +5.25V. For normal operation, bypass VCC to GND with a 0.1μF ceramic capacitor. For full ESD protection, bypass VCC to GND with 1μF ceramic capacitor. Driver Output Enable. Pull DE low to enable the outputs. Force DE high to three-state the outputs. Drive RE a nd DE h igh to enter lowpower shutdown mode. 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. -50mV, MAX13442E/MAX13443E/MAX13444E RO RE DE 4 — DI 5 6 7 8 5 6 7 8 GND A B VCC — 3 DE — 4 TXD ______________________________________________________________________________________ 11 ±15kV ESD-Protected, ±80V Fault-Protected, Fail-Safe RS-485/J1708 Transceivers MAX13442E/MAX13443E/MAX13444E Function Tables Table 1. MAX13442E/MAX13443E (RS-485/RS-422) TRANSMITTING INPUTS RE 0 0 0 1 1 1 DE 0 1 1 0 1 1 DI X 0 1 X 0 1 A High-Z 0 1 Shutdown 0 1 OUTPUTS B High-Z 1 0 Shutdown 1 0 RE 0 0 0 1 1 Table 3. MAX13442E/MAX13443E (RS-485/RS-422) RECEIVING INPUTS DE X X X 1 0 (VA - VB) -0.05V -0.2V Open/shorted X X OUTPUTS RO 1 0 1 H igh-Z Shutdown X = Don’t care. X = Don’t care. Table 2. MAX13444E (J1708) Application TRANSMITTING INPUTS TXD 0 1 0 1 DE 1 1 0 0 A High-Z High-Z 0 High-Z OUTPUTS B High-Z High-Z 1 High-Z CONDITIONS — — — Dominant state Recessive state Table 4. MAX13444E (RS-485/RS-422) RECEIVING INPUTS RE 0 0 0 1 1 DE X X X 0 1 (VA - VB) -0.05V -0.2V Open/shorted X X OUTPUTS RO 1 0 1 H igh-Z Shutdown X = Don’t care. 12 ______________________________________________________________________________________ ±15kV ESD-Protected, ±80V Fault-Protected, Fail-Safe RS-485/J1708 Transceivers Detailed Description The MAX13442E/MAX13443E/MAX13444E fault-protected transceivers for RS-485/RS-422 and J1708 communication contain one driver and one receiver. These devices feature fail-safe 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 MAX13442E/MAX13444E 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 MAX13443E driver is not slewrate limited, allowing transmit speeds up to 10Mbps. ver outputs/receiver inputs of the MAX13442E/ MAX13444E withstand voltage faults up to ±80V (±60V for the MAX13443E) with respect to ground without damage. Protection is guaranteed regardless whether the device is active, shut down, or without power. MAX13442E/MAX13443E/MAX13444E True Fail-Safe The MAX13442E/MAX13443E/MAX13444E 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 Protection As with all Maxim devices, ESD-protection structures are incorporated on all pins to protect against ESD encountered during handling and assembly. The MAX13442E/MAX13443E/MAX13444E 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 MAX13442E/MAX13443E/ MAX13444E 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. 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. 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 1–4). ESD Test Conditions ESD performance depends on a number of conditions. Contact Maxim for a reliability report that documents test setup, methodology, and results. 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 1.5kΩ resistor. Low-Power Shutdown The MAX13442E/MAX13443E/MAX13444E offer a lowpower shutdown mode. Force DE low and RE high to shut down the MAX13442E/MAX13443E. Force DE and RE high to shut down the MAX13444E. 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 MAX13442E/MAX13443E enter shutdown. In shutdown, the devices consume a maximum 20µA supply current. 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 +160°C. Normal operation resumes when the die temperature cools to +140°C, resulting in a pulsed output during continuous short-circuit conditions. ±80V 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/TIA-485 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 dri- ______________________________________________________________________________________ 13 ±15kV ESD-Protected, ±80V Fault-Protected, Fail-Safe RS-485/J1708 Transceivers MAX13442E/MAX13443E/MAX13444E Hot-Swap Capability Hot-Swap Inputs Inserting circuit boards into a hot, or powered, backplane may cause voltage transients on DE, 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 MAX13442E/MAX13443E/ MAX13444E enable inputs to a defined logic level. Meanwhile, leakage currents of up to 10µA 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 MAX13442E/MAX13443E/MAX13444E feature hot-swap input circuitry on DE, and RE to guard against unwanted driver activation during hot-swap situations. The MAX13444E 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 10µs, and until the current into DE exceeds 200µA. 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 15µs timer turns on M2 and sets the SR latch, which also turns on M1. Transistors M2, a 2mA current sink, and M1, a 100µA current sink, pull DE to GND through a 5.6kΩ resistor. M2 pulls DE to the disabled state against an external parasitic capacitance up to 100pF that may drive DE high. After 15µs, 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 R E uses two PMOS devices to pull RE to VCC. RC 1MΩ CHARGE-CURRENTLIMIT RESISTOR HIGHVOLTAGE DC SOURCE RD 1.5kΩ DISCHARGE RESISTANCE VCC 15μs TIMER DEVICE UNDER TEST Cs 100pF STORAGE CAPACITOR TIMER Figure 9a. Human Body ESD Test Model DE (HOT SWAP) IP 100% 90% AMPERES 36.8% 10% 0 0 tRL TIME tDL CURRENT WAVEFORM Ir PEAK-TO-PEAK RINGING (NOT DRAWN TO SCALE) 5.6kΩ 100μA M1 2mA M2 Figure 10. Simplified Structure of the Driver Enable Pin (DE) Figure 9b. Human Body Model Current Waveform 14 ______________________________________________________________________________________ ±15kV ESD-Protected, ±80V Fault-Protected, Fail-Safe RS-485/J1708 Transceivers Applications Information 128 Transceivers on the Bus The MAX13442E/MAX13443E/MAX13444E transceivers 1/4-unit-load receiver input impedance (48kΩ) 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. 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) where tRISE is the transmitter’s rise time. For example, the MAX13442E’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. MAX13442E/MAX13443E/MAX13444E Reduced EMI and Reflections The MAX13442E/MAX13444E 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 MAX13443E. High-frequency harmonic components with large amplitudes are evident. Figure 12 shows the same signal displayed for the MAX13442E 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. RS-485 Applications The MAX13442E/MAX13443E/MAX13444E transceivers provide bidirectional data communications on multipoint bus transmission lines. Figure 13 shows a typical network application 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. 20dB/div 20dB/div 2V/div 2V/div 0 500kHz/div 5.00MHz 0 500kHz/div 5.00MHz Figure 11. Driver Output Waveform and FFT Plot of the MAX13443E Transmitting a 125kHz Signal Figure 12. Driver Output Waveform and FFT Plot of the MAX13442E Transmitting a 125kHz Signal ______________________________________________________________________________________ 15 ±15kV ESD-Protected, ±80V Fault-Protected, Fail-Safe RS-485/J1708 Transceivers MAX13442E/MAX13443E/MAX13444E J1708 Applications The MAX13444E is designed for J1708 applications. To configure the MAX13444E, 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 14. 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 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. 120Ω DI D DE RO RE R R B 120Ω B D DI DE A B A B A A R RO RE R MAX13442E MAX13443E DI D D DE RO RE DI DE RO RE Figure 13. MAX13442E/MAX13443E Typical RS-485 Network 16 ______________________________________________________________________________________ ±15kV ESD-Protected, ±80V Fault-Protected, Fail-Safe RS-485/J1708 Transceivers Chip Information DE MAX13442E/MAX13443E/MAX13444E PROCESS: BiCMOS R1 4.7kΩ R3 47Ω C1 2.2nF J1708 BUS Package Information For the latest package outline information and land patterns (footprints), go to www.maxim-ic.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. PACKAGE TYPE 8 SO PACKAGE CODE S8+4 OUTLINE NO. 21-0041 LAND PATTERN NO. 90-0096 TX TXD D B MAX13444E A RX RO R C2 2.2nF R4 47Ω R2 4.7kΩ VCC RE Figure 14. J1708 Application Circuit (See Tables 2 and 4) Pin Configurations and Typical Operating Circuits (continued) DE + RO 1 R 8 7 6 D 5 VCC B A GND RO 1 RE 2 DE TXD 3 4 RE 2 DE 3 + R 8 VCC 7B 6 D A 5 GND RT MAX13444E D B RT A R RE RO TXD TXD 4 SO SO ______________________________________________________________________________________ 17 ±15kV ESD-Protected, ±80V Fault-Protected, Fail-Safe RS-485/J1708 Transceivers MAX13442E/MAX13443E/MAX13444E Revision History REVISION NUMBER 0 REVISION DATE 10/05 Initial release Corrected the part numbers in the conditions for VOC in the DC Electrical Characteristics table; corrected the A, B current units from mA to μA for the A, B Current vs. A, B Voltage (to Ground) graphs in the Typical Operating Characteristics section Added lead(Pb)-free parts to the Ordering Information t able; added the soldering temperature to the Absolute Maximum Ratings section; updated Table 2 outputs Added an automotive qualified part to the Ordering Information; added the P ackage Thermal Characteristics section DESCRIPTION PAGES CHANGED — 1 3/06 2, 7 2 3 11/10 3/11 1, 2, 12 1, 2 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. 18 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2011 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.