±15kV ESD-Protected, ±60V Fault-Protected, 10Mbps, Fail-Safe RS-485/J1708 Transceivers

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1 MX344E MX3444E ±15kV ES-Protected, ±6V Fault-Protected, 1Mbps, Fail-Safe S-485/J178 Transceivers General escription The MX344E MX3444E fault-protected S-485 and J178 transceivers feature ±6V 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 18 transceivers on a single bus. The devices operate from a 5V supply at data rates of up to 1Mbps. 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 ES protection eliminates costly external protection devices. The MX344E MX3444E are available in 8-pin SO and PIP packages and are specified over industrial and automotive temperature ranges. pplications S-4/S-485 Communications Industrial Networks Telecommunications Systems HVC Controls Selector Guide PT TYPE T TE (Mbps) LOW-POWE SHUTOWN Features ±15kV ES Protection ±6V Fault Protection Guaranteed 1Mbps ata ate (MX3441E/MX3443E) Hot Swappable for Telecom pplications True Fail-Safe eceiver Inputs Enhanced Slew-ate-Limiting Facilitates Error-Free ata Transmission (MX344E/MX344E/MX3444E) llow Up to 18 Transceivers on the us -7V to +1V Common-Mode Input ange utomotive Temperature ange (-4 C to +15 C) Industry-Standard Pinout Ordering Information PT TEMP NGE PIN-PCKGE MX344EES+ -4 C to +85 C 8 SO MX344EEP+ -4 C to +85 C 8 PIP MX344ES+ -4 C to +15 C 8 SO MX344EP+ -4 C to +15 C 8 PIP +enotes a lead(pb)-free/ohs-compliant package. Ordering Information continued at end of data sheet. ECEIVE/IVE ENLE TNSCEIVES ON US HOT SWP MX344E S No Yes 18 Yes MX3441E S to 1 No Yes 18 Yes MX344E S Yes Yes 18 Yes MX3443E S to 1 Yes Yes 18 Yes MX3444E J178.5 Yes Yes 18 Yes (only E) Pin Configurations and Typical Operating Circuits TOP VIEW FULT 1 O E/E 3 I FULT 1 7 O 6 5 GN E/E I t 6 5 GN MX344E MX3441E t E/E I O IP/SO IP/SO Pin Configurations and Typical Operating Circuits continued at end of data sheet. FULT ; ev 3; 4/14

2 MX344E MX3444E ±15kV ES-Protected, ±6V Fault-Protected, 1Mbps, Fail-Safe S-485/J178 Transceivers bsolute Maximum atings Voltages eferenced to GN...+7V FULT, E/E, E, E, E, I, TX V to ( +.3V), (Note 1)...±6V O V to ( +.3V) Short-Circuit uration (O,, )...Continuous Continuous Power issipation (T = +7 C) SO (derate 5.9mW/ C above +7 C)...471mW PIP (derate 9.9mW/ C above +7 C)...77mW Operating Temperature anges MX344_EE C to +85 C MX344_E C to +15 C Storage Temperature ange C to +15 C Junction Temperature C Lead Temperature (soldering, 1s)...+3 C Soldering Temperature (reflow)...+6 C Note 1:, must be terminated with 54Ω or 1Ω to guarantee ±6V fault protection. Stresses beyond those listed under bsolute Maximum atings 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. C Electrical Characteristics ( = +4.75V to +5.5V, T = T MIN to T MX, unless otherwise noted. Typical values are at = +5V and T = +5 C.) IVE PMETE SYMOL CONITIONS MIN TYP MX UNITS ifferential river Output V O Figure 1, L = 1Ω V Figure 1, L = 54Ω 1.5 Change in Magnitude of ifferential Output Voltage river Common-Mode Output Voltage Change in Magnitude of Common-Mode Voltage IVE LOGIC V O Figure 1, L = 1Ω or 54Ω (Note ). V V OC Figure 1, L = 1Ω or 54Ω / 3 V V OC Figure 1, L = 1Ω or 54Ω (Note ). V river Input High Voltage V IH V river Input Low Voltage V IL.8 V river Input Current I IN ± µ river Short-Circuit Output Current (Note 3) river Short-Circuit Foldback Output Current ECEIVE Input Current I,, eceiver ifferential Threshold Voltage V V OUT +1V +35 I OS -7V V OUT -35 ( - 1V) V OUT +1V (Note 3) +5 I OSF -7V V OUT +1V (Note 3) -5 = GN, V, = 1V 5 V, = -7V -15 V, = ±6V ±6 m V TH -7V V CM +1V - -5 mv eceiver Input Hysteresis V TH 5 mv m m µ Maxim Integrated

3 MX344E MX3444E ±15kV ES-Protected, ±6V Fault-Protected, 1Mbps, Fail-Safe S-485/J178 Transceivers C Electrical Characteristics (continued) ( = +4.75V to +5.5V, T = T MIN to T MX, unless otherwise noted. Typical values are at = +5V and T = +5 C.) ECEIVE LOGIC PMETE SYMOL CONITIONS MIN TYP MX UNITS Output High Voltage V OH Figure, I OH = -1.6m Output Low Voltage V OL Figure, I OL = 1m.4 V Three-State Output Current at eceiver.6 I OZ V V, ±1 µ eceiver Input esistance IN -7V V CM +1V 48 kw eceiver Output Short-Circuit Current CONTOL I OS V V O ±95 m Control Input High Voltage VCIH E, E, E, E/E V Input Current Latch uring First ising Edge SUPPLY CUENT Normal Operation I Q I = No load, or GN I IN E, E/E, E 9 µ MX344E (E/E = ), MX344E (E =, E = GN), MX3444E (E = E = GN) MX3441E (E/E = ), MX3443E (E =, E = GN) E = GN, E = (MX344E/ MX3443E) 3 1 V m Supply Current in Shutdown Mode Supply Current with Output Shorted to ±6V I SHN ISHT E = GN, E =, T = +5 C (MX344E/MX3443E) E = E = (MX3444E) 1 E = E =, T = +5 C (MX3444E) 1 E = GN, E = GN, no load output in three-state (MX3443E) 1 µ ±15 m Protection Specifications ( = +4.75V to +5.5V, T = T MIN to T MX, unless otherwise noted. Typical values are at = +5V and T = +5 C.) PMETE SYMOL CONITIONS MIN TYP MX UNITS Overvoltage Protection, ; SOUCE =, L = 54Ω ±6 V ES Protection, Human ody Model ±15 kv FULT ETECTION eceiver ifferential Threshold F IPH V CM = V, high limit 7 45 mv eceiver ifferential Threshold F IPL V CM = V, low limit mv Fault-etection Common-Mode Input Voltage Positive 1 V Fault-etection Common-Mode Input Voltage Negative -7 V Maxim Integrated 3

4 MX344E MX3444E ±15kV ES-Protected, ±6V Fault-Protected, 1Mbps, Fail-Safe S-485/J178 Transceivers Switching Characteristics (MX344E/MX344E/MX3444E) ( = +4.75V to +5.5V, T = T MIN to T MX, unless otherwise noted. Typical values are at = +5V and T = +5 C.) PMETE SYMOL CONITIONS MIN TYP MX UNITS river Propagation elay t PLH, t PLH MX344E/MX344E, Figure 3, L = 54Ω, C L = 5pF ns MX3444E, IFF = 6Ω, C IFF = 1pF river ifferential Propagation elay river ifferential Output Transition Time t PLH, t PHL Figure 4, L = 54Ω, C L = 5pF ns t LH,t HL Figure 4, L = 54Ω, C L = 5pF ns river Output Skew t SKEW, t SKEW L = 54Ω, C L = 5pF, t SKEW = t PLH - t PHL, t SKEW = t PLH - t PHL 35 ns ifferential river Output Skew t SKEW L = 54Ω, C L = 5pF, t SKEW = t PLH - t PHL ns Maximum ata ate f MX 5 kbps river Enable Time to Output High t PZH Figure 5, L = 5Ω, C L = 5pF ns river isable Time from Output High t PHZ Figure 5, L = 5Ω, C L = 5pF ns river Enable Time from Shutdown to Output High t PHS Figure 5, L = 5Ω, C L = 5pF (MX344E/MX3444E) 4. µs river Enable Time to Output Low t PZL Figure 6, L = 5Ω, C L = 5pF ns river isable Time from Output Low t PLZ Figure 6, L = 5Ω, C L = 5pF ns river Enable Time from Shutdown to Output Low t PLS Figure 6, L = 5Ω, C L = 5pF (MX344E/MX3444E) river Time to Shutdown t SHN L = 5Ω, C L = 5pF (MX344E/MX3444E) eceiver Propagation elay 4. µs 8 ns t PLH, t PHL Figure 7, C L = pf, V I = V, V CM = V ns eceiver Output Skew t SKEW C L = pf, t SKEW = t PLH - t PHL ns eceiver Enable Time to Output High t PZH Figure 8, L = 1kΩ, C L = pf ns eceiver isable Time from Output High eceiver Wake Time from Shutdown t PWKE Figure 8, L = 1Ω, C L = pf (MX344E/MX3444E) t PHZ Figure 8, L = 1kΩ, C L = pf ns 4. µs eceiver Enable Time to Output Low t PZL Figure 8, L = 1kΩ, C L = pf ns eceiver isable Time from Output Low t PLZ Figure 8, L = 1Ω, CL = pf ns eceiver Time to Shutdown t SHN L = 5Ω, C L = 5pF (MX344E/MX3444E) 8 ns Maxim Integrated 4

5 MX344E MX3444E ±15kV ES-Protected, ±6V Fault-Protected, 1Mbps, Fail-Safe S-485/J178 Transceivers Switching Characteristics (MX3441E/MX3443E) ( = +4.75V to +5.5V, T = T MIN to T MX, unless otherwise noted. Typical values are at = +5V and T = +5 C.) PMETE SYMOL CONITIONS MIN TYP MX UNITS river Propagation elay river ifferential Propagation elay river ifferential Output Transition Time t PLH, t PLH Figure 3, L = 7Ω, C L = 5pF 6 ns t PLH, t PHL Figure 4, L = 54Ω, C L = 5pF 6 ns t LH,t HL Figure 4, L = 54Ω, C L = 5pF 5 ns river Output Skew t SKEW, t SKEW L = 54Ω, C L = 5pF, t SKEW = t PLH - t PHL, t SKEW = t PLH - t PHL 1 ns ifferential river Output Skew t SKEW L = 54Ω, C L = 5pF, t SKEW = t PLH - t PHL 1 ns Maximum ata ate f MX 1 Mbps river Enable Time to Output High t PZH Figure 5, L = 5Ω, C L = 5pF 1 ns river isable Time from Output High t PHZ Figure 5, L = 5Ω, C L = 5pF 1 ns river Enable Time from Shutdown to Output High t PHS Figure 5, L = 5Ω, C L = 5pF (MX3443E) 4. µs river Enable Time to Output Low t PZL Figure 6, L = 5Ω, C L = 5pF 1 ns river isable Time from Output Low t PLZ Figure 6, L = 5Ω, C L = 5pF 1 ns river Enable Time from Shutdown to Output Low t PLS Figure 6, L = 5Ω, C L = 5pF (MX3443E) 4. µs river Time to Shutdown t SHN Figure 6, L = 5Ω, C L = 5pF (MX3443E) 8 ns eceiver Propagation elay t PLH, t PHL Figure 7, C L = pf, V I = V, V CM = V 85 ns eceiver Output Skew t SKEW C L = pf, t SKEW = t PLH - t PHL 15 ns eceiver Enable Time to Output High t PZH Figure 8, L = 1kΩ, C L = pf 4 ns eceiver isable Time from Output High t PHZ Figure 8, L = 1kΩ, C L = pf 4 ns eceiver Wake Time from Shutdown t PWKE Figure 8, L = 1kΩ, C L = pf (MX3443E) 4. µs eceiver Enable Wake Time from Shutdown t PSH Figure 8, L = 1kΩ, C L = pf 4 ns eceiver isable Time from Output Low t PLZ Figure 8, L = 1kΩ, C L = pf 4 ns eceiver Time to Shutdown t SHN L = 5Ω, C L = 5pF (MX3443E) 8 ns Note : V O and V OC are the changes in V O and V OC, respectively, when the I 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. Maxim Integrated 5

6 MX344E MX3444E ±15kV ES-Protected, ±6V Fault-Protected, 1Mbps, Fail-Safe S-485/J178 Transceivers Typical Operating Characteristics ( = +5V, T = +5 C, unless otherwise noted.) SUPPLY CUENT (m) NO-LO SUPPLY CUENT vs. TEMPETUE IVE N ECEIVE ENLE IVE ISLE, ECEIVE ENLE MX344E toc1 SUPPLY CUENT (m) NO-LO SUPPLY CUENT vs. TEMPETUE IVE N ECEIVE ENLE IVE ISLE, ECEIVE ENLE MX344E toc SUPPLY CUENT () SHUTOWN SUPPLY CUENT vs. TEMPETUE MX3443E toc3 1 MX3441E/MX3443E WTEMPETUE ( C) 4 MX344E/MX344E/MX3444E TEMPETUE ( C) MX344E/MX3443E/MX3444E TEMPETUE ( C) ECEIVE OUTPUT CUENT (m) ECEIVE OUTPUT CUENT vs. OUTPUT LOW VOLTGE MX3443E toc4 ECEIVE OUTPUT CUENT (m) ECEIVE OUTPUT CUENT vs. OUTPUT HIGH VOLTGE MX3443E toc5 ECEIVE OUTPUT VOLTGE (V) ECEIVE OUTPUT VOLTGE vs. TEMPETUE V OH, I OUT = +1m V OL, I OUT = -1m MX3443E toc OUTPUT LOW VOLTGE (V) OUTPUT HIGH VOLTGE (V) TEMPETUE ( C) IVE OUTPUT CUENT (m) IVE OUTPUT CUENT vs. IFFEENTIL OUTPUT VOLTGE IFFEENTIL OUTPUT VOLTGE (V - V ) (V) MX3443E toc7 IFFEENTIL OUTPUT VOLTGE (V) IFFEENTIL OUTPUT VOLTGE vs. TEMPETUE L = 1Ω L = 54Ω.5 MX3441E/MX3443E TEMPETUE ( C) MX3443E toc8, CUENT (µ) , CUENT vs., VOLTGE (TO GOUN) L = 54Ω IVE ISLE, ECEIVE ENLE , VOLTGE (V) MX3443E toc Maxim Integrated 6

7 MX344E MX3444E ±15kV ES-Protected, ±6V Fault-Protected, 1Mbps, Fail-Safe S-485/J178 Transceivers Test Circuits and Waveforms L I V O L V OC Figure 1. river V O and V OC V I O V OL I OL (+) V OH IOH (-) Figure. eceiver V OH and V OL 3V V OM I GENETO (NOTE 4) I 5Ω S1 L C L = 5pF (NOTE 5) OUT t PLH V OM V OM t PHL V OH V OL V OH + V OL V OM = ª t PHL V OM V OM t PLH V OH V OL Figure 3. river Propagation Times 3V GENETO (NOTE 4) I 5Ω C L C L L OUT C L = 5pF (NOTE 5) I ( ) t PLH 5% 1% t LH 9% 9% t PHL 5% 1% t HL ª.V ª -.V Figure 4. river ifferential Output elay and Transition Times Maxim Integrated 7

8 MX344E MX3444E ±15kV ES-Protected, ±6V Fault-Protected, 1Mbps, Fail-Safe S-485/J178 Transceivers Test Circuits and Waveforms (continued) O 3V GENETO (NOTE 4) I 5W E S1 C L = 5pF (NOTE 5) V OM = V OH + V OL ª, L = 5W E t PZH t PHS, V OM t PHZ.5V 3V V OH Figure 5. river Enable and isable Times 3V L = 5Ω S1 I O 3V, GENETO (NOTE 4) E 5Ω C L = 5pF (NOTE 5) E, t PZL t PLS VOM t PLZ.5V V OL Figure 6. river Enable and isable Times GENETO (NOTE 4) 5Ω V I O C L = pf (NOTE 5) ( ) 1.V t PLH 1.V t PHL.V 1.V O V OM V OM Figure 7. eceiver Propagation elay Maxim Integrated 8

9 MX344E MX3444E ±15kV ES-Protected, ±6V Fault-Protected, 1Mbps, Fail-Safe S-485/J178 Transceivers Test Circuits and Waveforms (continued) - S3 V I O 1kΩ S1 S GENETO (NOTE 4) 5Ω C L = pf (NOTE 5) E O t PZH t PSH t PWKE 3V V OH S1 OPEN S CLOSE V S3 = E O t PZL t PSL 3V S1 CLOSE S OPEN V S3 = - V OL E 3V S1 OPEN S CLOSE V S3 = E 3V S1 CLOSE S OPEN V S3 = - t PHZ O.5V V OH O t PLZ.5V V OL Figure 8. eceiver Enable and isable Times Note 4: The input pulse is supplied by a generator with the following characteristics: f = 5MHz, 5% duty cycle; tr 6ns; Z = 5Ω. Note 5: C L includes probe and stray capacitance. Maxim Integrated 9

10 MX344E MX3444E ±15kV ES-Protected, ±6V Fault-Protected, 1Mbps, Fail-Safe S-485/J178 Transceivers Pin escription MX344E MX3441E PIN MX344E MX3443E MX3444E NME 1 FULT FUNCTION Fault output. 1 = fault; = normal operation or under the following conditions: - differential <mv shorted to shorted to a voltage within the common-mode range (detected only when the driver is enabled) shorted to a voltage within the common-mode range (detected only when the driver is enabled) or outside the common-mode range 1 1 O eceiver Output. If receiver enabled and (-) -5mV, O = high; if (-) -mv, O = low. E eceiver Output Enable. Pull E low to enable O. 3 E 3 E/E 3 E 4 4 I 4 TX GN Ground river Output Enable. Pull E low to enable the outputs Force E high to three-state the outputs. rive E and E high to enter low-power shutdown mode. river/eceiver Output Enable. Pull E/E low to threestate the driver output and enable O. Force E/E high to enable driver output and three-state O river Output Enable. Force E high to enable driver. Pull E low to three-state the driver output. rive E high and pull E low to enter low-power shutdown mode. river Input. logic-low on I forces the noninverting output low and the inverting output high. logic-high on I forces the noninverting output high and the inverting output low. J178 Input. logic-low on TX forces outputs and to the dominant state. logic-high on TX forces outputs and to the recessive state Noninverting eceiver Input/river Output Inverting eceiver Input/river Output Positive Supply, = +4.75V to +5.5V Maxim Integrated 1

11 MX344E MX3444E ±15kV ES-Protected, ±6V Fault-Protected, 1Mbps, Fail-Safe S-485/J178 Transceivers Function Tables Table 1. MX344E/MX3441E Fault Table X = on t care. INPUTS - VI IFFEENTIL INPUT VOLTGE.45V COMMON-MOE VOLTGE 1V and -7V Note 1: eceiver output may oscillate with this differential input condition. O OUTPUTS FULT CONITIONE Y ELY FULT CONITION 1 Normal operation <.45V and.7v 1 Indeterminate Indeterminate <.7V and -.5V 1 1 Low-input differential voltage -.5V and -.V Indeterminate (Note 1) 1 Low-input differential voltage -.V and >-.7V 1 Low-input differential voltage -.7V and >-.45V Indeterminate -.45V Indeterminate X <-7V or >+1V Indeterminate 1 Outside common-mode voltage range Table. MX344E/MX3441E (S-485/S-4) TNSMITTING INPUTS OUTPUTS E/E I X High-Z High-Z X = on t care. Table 4. MX3444E (J178) pplication X = on t care. TNSMITTING INPUTS OUTPUTS CONITIONS TX E 1 High-Z High-Z 1 1 High-Z High-Z 1 ominant state 1 High-Z High-Z ecessive state Table 3. MX344E/MX3443E (S-485/S-4) X = on t care. Table 5. MX344E/MX3441E (S-485/S-4) X = on t care. INPUTS INPUTS TNSMITTING ECEIVING OUTPUTS E E I X High-Z High-Z X Shutdown Shutdown OUTPUTS E/E ( - ) O -.5V 1 -.V Open/shorted 1 1 X High-Z Maxim Integrated 11

12 MX344E MX3444E ±15kV ES-Protected, ±6V Fault-Protected, 1Mbps, Fail-Safe S-485/J178 Transceivers Function Tables (continued) Table 6. MX344E/MX3443E (S-485/S-4) ECEIVING INPUTS OUTPUTS E E ( - ) O X -.5V 1 X -.V X Open/shorted X High-Z 1 X Shutdown X = on t care. etailed escription The MX344E MX3444E fault-protected transceivers for S-485/S-4 and J178 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). ll 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 MX344E/MX344E/ MX3444E feature a reduced slew-rate driver that minimizes EMI and reduces reflections caused by improperly terminated cables, allowing error-free data transmission up to 5kbps (see the educed EMI and eflections section). The MX3441E/ MX3443E drivers are not slew-rate limited, allowing transmit speeds up to 1Mbps. river The driver accepts a single-ended, logic-level input (I) and transfers it to a differential, S-485/S-4 level output ( and ). easserting the driver enable places the driver outputs ( and ) into a high-impedance state. eceiver The receiver accepts a differential, S-485/S-4 level input ( and ), and transfers it to a single-ended, logic-level output (O). easserting the receiver enable places the receiver inputs ( and ) into a high-impedance state (see Tables 1 7). Table 7. MX3444E (S-485/S-4) X = on t care. INPUTS ECEIVING OUTPUTS E E ( - ) O X -.5V 1 X -.V X Open/shorted 1 1 X High-Z 1 1 X Shutdown Low-Power Shutdown (MX344E/MX3443E/ MX3444E) The MX344E/MX3443E/MX3444E offer a lowpower shutdown mode. Force E low and E high to shut down the MX344E/MX3443E. Force E and E high to shut down the MX3444E. time delay of 5ns prevents the device from accidentally entering shutdown due to logic skews when switching between transmit and receive modes. Holding E low and E high for at least 8ns guarantees that the MX344E/MX3443E enter shutdown. In shutdown, the devices consume a maximum µ supply current. ±6V Fault Protection The driver outputs/receiver inputs of S-485 devices in industrial network applications often experience voltage faults resulting from shorts to the power grid that exceed the -7V to +1V range specified in the EI/TI-485 standard. In these applications, ordinary S-485 devices (typical absolute maximum -8V to +1.5V) require costly external protection devices. To reduce system complexity and eliminate this need for external protection, the driver outputs/receiver inputs of the MX344E MX3444E withstand voltage faults up to ±6V with respect to ground without damage. Protection is guaranteed regardless whether the device is active, shut down, or without power. True Fail-Safe The MX344E MX3444E use a -5mV to -mv 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 -5mV to -mv threshold complies with the ±mv threshold EI/TI-485 standard. Maxim Integrated 1

13 MX344E MX3444E ±15kV ES-Protected, ±6V Fault-Protected, 1Mbps, Fail-Safe S-485/J178 Transceivers ±15kV ES Protection s with all Maxim devices, ES-protection structures are incorporated on all pins to protect against ES encountered during handling and assembly. The MX344E MX3444E receiver inputs/driver outputs (, ) have extra protection against static electricity found in normal operation. Maxim s engineers have developed state-ofthe-art structures to protect these pins against ±15kV ES without damage. fter an ES event, the MX344E MX3444E continue working without latchup. ES protection can be tested in several ways. The receiver inputs are characterized for protection to ±15kV using the Human ody Model. ES Test Conditions ES performance depends on a number of conditions. Contact Maxim for a reliability report that documents test setup, methodology, and results. Human ody Model Figure 9a shows the Human ody Model, and Figure 9b shows the current waveform it generates when discharged into a low impedance. This model consists of a 1pF capacitor charged to the ES voltage of interest, which is then discharged into the device through a 1.5kΩ resistor. river 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 +16 C. Normal operation resumes when the die temperature cools to +14 C, resulting in a pulsed output during continuous short-circuit conditions. C 1MΩ CHGE-CUENT- LIMIT ESISTO 1.5kΩ ISCHGE ESISTNCE MPEES I P 1% 9% Ir PEK-TO-PEK INGING (NOT WN TO SCLE) HIGH- VOLTGE C SOUCE Cs 1pF STOGE CPCITO EVICE UNE TEST 36.8% 1% t L TIME t L CUENT WVEFOM Figure 9a. Human ody ES Test Model Figure 9b. Human ody Model Current Waveform Maxim Integrated 13

14 MX344E MX3444E ±15kV ES-Protected, ±6V Fault-Protected, 1Mbps, Fail-Safe S-485/J178 Transceivers Hot-Swap Capability Hot-Swap Inputs Inserting circuit boards into a hot, or powered, backplane may cause voltage transients on E, E/E, E, and receiver inputs and that can lead to data errors. For example, upon initial circuit board insertion, the processor undergoes a power-up sequence. uring this period, the high-impedance state of the output drivers makes them unable to drive the MX344E MX3444E enable inputs to a defined logic level. Meanwhile, leakage currents of up to 1µ from the high-impedance output, or capacitively coupled noise from or GN, could cause an input to drift to an incorrect logic state. To prevent such a condition from occurring, the MX344E MX3443E feature hot-swap input circuitry on E, E/E, and E to guard against unwanted driver activation during hot-swap situations. The MX3444E has hot-swap input circuitry only on E. When rises, an internal pulldown (or pullup for E) circuit holds E low for at least 1µs, and until the current into E exceeds µ. fter the initial power-up sequence, the pulldown circuit becomes transparent, resetting the hot-swap tolerable input. Hot-Swap Input Circuitry t the driver-enable input (E), there are two nmos devices, M1 and M (Figure 1). When ramps from zero, an internal 15µs timer turns on M and sets the S latch, which also turns on M1. Transistors M, a m current sink, and M1, a 1µ current sink, pull E to GN through a 5.6kW resistor. M pulls E to the disabled state against an external parasitic capacitance up to 1pF that may drive E high. fter 15µs, the timer deactivates M while M1 remains on, holding E low against three-state leakage currents that may drive E high. M1 remains on until an external current source overcomes the required input current. t this time, the S latch resets M1 and turns off. When M1 turns off, E reverts to a standard, high-impedance CMOS input. Whenever drops below 1V, the input is reset. complementary circuit for E uses two pmos devices to pull E to. pplications Information 18 Transceivers on the us The MX344E MX3444E transceivers 1/4-unit-load receiver input impedance (48kW) allows up to 18 transceivers connected in parallel on one communication line. Connect any combination of these devices, and/or other S-485 devices, for a maximum of 3-unit loads to the line. educed EMI and eflections The MX344E/MX344E/MX3444E 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 15kHz signal transmitted by a MX3443E. High-frequency harmonic components with large amplitudes are evident. Figure 1 shows the same signal displayed for a MX344E transmitting under the same conditions. Figure 1 s high-frequency harmonic components are much lower in amplitude, compared with Figure 11 s, and the potential for EMI is significantly reduced. E (HOT SWP) TIME TIME 5.6kΩ M1 15µs m 1µ Figure 1. Simplified Structure of the river Enable Pin (E) M Maxim Integrated 14

15 MX344E MX3444E ±15kV ES-Protected, ±6V Fault-Protected, 1Mbps, Fail-Safe S-485/J178 Transceivers 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 = t ISE /(1 x 1.5ns/ft) where t ISE is the transmitter s rise time. For example, the MX344E s rise time is typically 8ns, which results in excellent waveforms with a stub length up to 53ft. system can work well with longer unterminated stubs, even with severe reflections, if the waveform settles out before the UT samples them. S-485 pplications The MX344E MX3443E transceivers provide bidirectional data communications on multipoint bus transmission lines. Figures 13 and 14 show a typical network applications circuit. The S-485 standard covers line lengths up to 4ft. 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. J178 pplications The MX3444E is designed for J178 applications. To configure the MX3444E, connect E and E to GN. Connect the signal to be transmitted to TX. Terminate the bus with the load circuit as shown in Figure 15. The drivers used by SE J178 are used in a dominant-mode application. E is active low; a high input on E places the outputs in high impedance. When the driver is disabled (TX high or E high), the bus is pulled high by external bias resistors 1 and. 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 and pulldown resistor on. 1 and provide the bias for the recessive state. C1 and C combine to form a 6MHz lowpass filter, effective for reducing FM interference., C1, 4, and C combine to form a 1.6MHz lowpass filter, effective for reducing M interference. ecause the bus is unterminated, at high frequencies, 3 and 4 perform a pseudotermination. This makes the implementation more flexible, as no specific termination nodes are required at the ends of the bus. d/div d/div V/div V/div 5kHz/div 5.MHz 5kHz/div 5.MHz Figure 11. river Output Waveform and FFT Plot of MX3443E Transmitting a 15kHz Signal Figure 1. river Output Waveform and FFT Plot of MX344E Transmitting a 15kHz Signal Maxim Integrated 15

16 MX344E MX3444E ±15kV ES-Protected, ±6V Fault-Protected, 1Mbps, Fail-Safe S-485/J178 Transceivers 1Ω 1Ω I E/E E/E I O FULT O FULT MX344E MX3441E I E/E O FULT I E/E O FULT Figure 13. MX344E/MX3441E Typical S-485 Network 1Ω 1Ω I E E I O E O E MX344E MX3443E I E O E I E O E Figure 14. MX344E/MX3443E Typical S-485 Network Maxim Integrated 16

17 MX344E MX3444E ±15kV ES-Protected, ±6V Fault-Protected, 1Mbps, Fail-Safe S-485/J178 Transceivers E Tx TX MX3444E x O E Figure 15. J178 pplication Circuit 1 4.7kΩ 3 47Ω C1.nF C.nF 4 47Ω 4.7kΩ J178 US Ordering Information (continued) PT TEMP NGE PIN-PCKGE MX3441EES+ -4 C to +85 C 8 SO MX3441EEP+ -4 C to +85 C 8 PIP MX3441ES+ -4 C to +15 C 8 SO MX3441EP+ -4 C to +15 C 8 PIP MX344EES+ -4 C to +85 C 8 SO MX344EEP+ -4 C to +85 C 8 PIP MX344ES+ -4 C to +15 C 8 SO MX344EP+ -4 C to +15 C 8 PIP MX3443ECS+ C to +7 C 8 SO MX3443ECP+ C to +7 C 8 PIP MX3443EES+ -4 C to +85 C 8 SO MX3443EEP+ -4 C to +85 C 8 PIP MX3443ES+ -4 C to +15 C 8 SO MX3443EP+ -4 C to +15 C 8 PIP MX3444EES+ -4 C to +85 C 8 SO MX3444EEP+ -4 C to +85 C 8 PIP MX3444ES+ -4 C to +15 C 8 SO MX3444EP+ -4 C to +15 C 8 PIP +enotes a lead(pb)-free/ohs-compliant package. Pin Configurations and Typical Operating Circuits (continued) TOP VIEW O E E I GN O E E I t 6 5 GN MX344E MX3443E t E I O IP/SO IP/SO E O E E TX VCC GN O E E TX VCC 7 t 6 5 GN MX3444E t E TX O IP/SO IP/SO E Maxim Integrated 17

18 MX344E MX3444E ±15kV ES-Protected, ±6V Fault-Protected, 1Mbps, Fail-Safe S-485/J178 Transceivers Chip Information POCESS: icmos Package Information For the latest package outline information and land patterns (footprints), go to Note that a +, #, or - in the package code indicates ohs status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of ohs status. PCKGE TYPE PCKGE COE OUTLINE NO. LN PTTEN NO. 8 SO S Maxim Integrated 18

19 MX344E MX3444E ±15kV ES-Protected, ±6V Fault-Protected, 1Mbps, Fail-Safe S-485/J178 Transceivers evision History EVISION NUME EVISION TE ESCIPTION PGES CHNGE 1/ Initial release 1 1/5 11/1 3 4/14 Corrected the supply current units from µ to m for the Shutdown Supply Current vs. Temperature graph in the Typical Operating Characteristics section; updated the outputs in Table 4; updated Figure 15 dded lead(pb)-free parts to the Ordering Information table; added the soldering temperature to the bsolute Maximum atings section; updated Table 4 outputs eleted Truck and Trailer pplications and utomotive pplications from pplications section 6, 11, 17 1,, 11, 17 1 For pricing, delivery, and ordering information, please contact Maxim irect at , or visit Maxim Integrated s website at Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance. Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc. 14 Maxim Integrated Products, Inc. 19