19-1941; Rev 1; 3/06 ±15kV ESD-Protected, Isolated, 3.3V RS-485/RS-422 Data Interfaces General Description ____________________________Features M The MAX3480EA/MAX3480EB are electrically isolated ♦ Isolated Data Interface Guaranteed to 1260VRMS A RS-485/RS-422 data-communications interfaces. The (1min) X RS-485/RS-422 I/O pins are protected against ±15kV electrostatic discharge (ESD) shocks, without latchup. ♦ ±15kV ESD Protection for I/O Pins 3 Transceivers, optocouplers, and a transformer are all ♦ Slew-Rate-Limited Data Transmission (160kbps for 4 included in one low-cost, 28-pin PDIP package. A sin- MAX3480EB) 8 gle +3.3V supply on the logic side powers both sides of the interface. ♦ High-Speed, Isolated, 2.5Mbps RS-485 Interface 0 The MAX3480EB features reduced-slew-rate drivers (MAX3480EA) E that minimize EMI and reduce reflections caused by ♦ Single +3.3V Supply A improperly terminated cables, allowing error-free data / ♦ Current Limiting and Thermal Shutdown for M transmission at data rates up to 160kbps. The MAX3480EA’s driver slew rate is not limited, allowing Driver Overload Protection A transmission rates up to 2.5Mbps. ♦ Standard 28-Pin PDIP Package X Drivers are short-circuit current limited and are protect- ♦ Allows Up to 128 Transceivers on the Bus ed against excessive power dissipation by thermal 3 shutdown circuitry that places the driver outputs into a 4 high-impedance state. The receiver input has a fail-safe 8 feature that guarantees a logic-high output if the input 0 is open circuit. E The MAX3480EA/MAX3480EB are guaranteed to with- B stand 1260VRMS (1min) or 1520VRMS (1s). Their isolated Pin Configuration inputs and outputs meet RS-485/RS-422 specifications. TOP VIEW ________________________Applications MAX3480EA Isolated RS-485/RS-422 Data Interface MAX3480EB Transceivers for EMI-Sensitive Applications VCC1 1 28 AC1 Industrial-Control Local Area Networks VCC2 2 27 AC2 Automatic Test Equipment D1 3 26 ISO VCC1 HVAC/Building Control Networks D2 4 25 B Telecom GND1 5 24 ISO RO DRV MAX845 MAX1487E FS 6 MAX487E 23 A Ordering Information SD 7 22 ISO DI IN DA TA VCC3 8 21 ISO DE IN TEMP PI N- PKG PART RA TE DI 9 20 ISO COM1 RANGE PA CK AG E * CODE (k b ps ) VCC4 10 19 ISO DI DRV MAX3480EACPI 0°C to +7 0°C 28 PDIP 2500 P28M-1 DE 11 18 ISO VCC2 MAX3480EAEPI -4 0°C to +8 5°C 28 PDIP 2500 P28M-1 GND2 12 17 ISO DE DRV MAX3480EBCPI 0°C to +7 0°C 28 PDIP 250 P28M-1 RO 13 16 ISO COM2 MAX3480EBEPI -4 0°C to +8 5°C 28 PDIP 250 P28M-1 VCC5 14 15 ISO RO LED *See the Reliability section at end of data sheet. ISOLATION BARRIER PDIP ________________________________________________________________Maxim Integrated Products 1 For pricing, delivery, and ordering information,please contact Maxim/Dallas Direct!at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

±15kV ESD-Protected, Isolated, 3.3V RS-485/RS-422 Data Interfaces B ABSOLUTE MAXIMUM RATINGS E With Respect to GND LED Forward Current (DI, DE, ISO RO LED)......................50mA Supply Voltage (VCC1, VCC2, VCC4, VCC5).......-0.3V to +3.8V Continuous Power Dissipation (TA= +70°C) 0 Supply Voltage (VCC3)........................................-0.3V to +7V 28-Pin PDIP (derate 9.09mW/°C above +70°C)............727mW 8 Control Input Voltage (SD, FS)............-0.3V to (VCC3+ 0.3V) Operating Temperature Ranges 4 Receiver Output Voltage (RO).............-0.3V to (VCC5+ 0.3V) MAX3480E_CPI..................................................0°C to +70°C With Respect to ISO COM MAX3480E_EPI...............................................-40°C to +85°C 3 Control Input Voltage (ISO DE _)......-0.3V to (ISO VCC_+ 0.3V) Storage Temperature Range.............................-65°C to +150°C X Driver Input Voltage (ISO DI _).....-0.3V to (ISO VCC_+ 0.3V) Lead Temperature (soldering, 10s).................................+300°C Receiver Output Voltage (ISO RO _)..-0.3V to (ISO VCC_+ 0.3V) A Driver Output Voltage (A, B)..............................-8V to +12.5V M Receiver Input Voltage (A, B)............................-8V to +12.5V Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional A/ 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. E 0 ELECTRICAL CHARACTERISTICS 8 (VCC= VCC1 = VCC2 = VCC4 = VCC5 = +3.0V to +3.6V, FS= 0, TA= TMINto TMAX, unless otherwise noted. Typical values are at VCC = 4 +3.3V and TA= +25°C.) (Notes 1, 2) 3 PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS X fSWL FS = 0 60 A Switch Frequency kHz fSWH FS = VCC or open 900 M MAX3480EA, RL = ∞ 130 250 DE´ = VCC or open RL = 54Ω 220 Operating Supply Current ICC mA MAX3480EB, RL = ∞ 80 200 DE´ = VCC or open RL = 54Ω 180 Shutdown Supply Current (Note 3) ISHDN SD = VCC3 0.2 µA VFSH High 2.4 FS Input Threshold V VFSL Low 0.8 FS Input Pullup Current IFSL FS low 50 µA FS Input Leakage Current IFSM FS high 10 pA Input High Voltage VIH DE´, DI´, Figure 1 VCC - 0.4 V Input Low Voltage VIL DE´, DI´, Figure 1 0.4 V Isolation Voltage VISO TA = +25°C, 1min (Note 4) 1260 VRMS VSDH High 2.4 1 Shutdown Input Threshold V VSDL Low 1 0.8 Isolation Resistance RISO TA = +25°C, VISO = ±50VDC 100 10,000 MΩ Isolation Capacitance CISO f = 1MHz 10 pF A, B, Y, and Z pins, tested at Human Body ESD Protection ESD ±15 kV Model Differential Driver Output VOD1 8 V (No Load) R = 50Ω (RS-422) 2 Differential Driver Output VOD2 R = 27Ω (RS-485), Figure 3 1.5 5.0 V Change in Magnitude of Driver R = 27Ω or 50Ω, Differential 0.3 Output Voltage for Complementary ∆VOD V Figure 3 Output States Common mode 0.3 2 _______________________________________________________________________________________

±15kV ESD-Protected, Isolated, 3.3V RS-485/RS-422 Data Interfaces ELECTRICAL CHARACTERISTICS (continued) M (VCC= VCC1 = VCC2 = VCC4 = VCC5 = +3.0V to +3.6V, FS= 0, TA= TMINto TMAX, unless otherwise noted. Typical values are at VCC = A +3.3V and TA= +25°C.) (Notes 1, 2) X PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 3 Driver Common-Mode Output VOC R = 27Ω or 50Ω, Figure 4 4 V 4 VIN = +12V 0.25 DE´ = 0, MAX3480EA 8 VIN = -7V -0.2 Input Current (A, B) ISO IIN VCC = 0 or mA 0 +3.6V MAX3480EB VIN = +12V 0.25 E VIN = -7V -0.2 A Receiver Input Resistance RIN -7V ≤ VCM ≤ 12V 48 kΩ / Receiver Differential Threshold VTH -7V ≤ VCM ≤ 12V -0.2 +0.2 V M Receiver Input Hysteresis ∆VTH VCM = 0 70 mV A Receiver Output Low Voltage VOL DI´ = VCC 0.4 V X Receiver Output High Current IOH VOUT = +3.6V, DI´ = 0 250 µA 3 Driver Short-Circuit Current ISO IOSD -7V ≤ VO ≤ 12V (Note 5) 100 mA 4 8 0 E B SWITCHING CHARACTERISTICS—MAX3480EA (VCC = VCC1 = VCC2 = VCC4 =VCC5 =+3.0V to +3.6V, FS= 0, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC= +3.3V and TA= +25°C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Driver Input to Output tPLH Figures 4, 6; RDIFF= 54Ω, 100 275 ns Propagation Delay tPHL CL1= CL2= 100pF 100 275 Driver Output Skew tSKEW Figures 4, 6; RDIFF = 54Ω, 25 100 ns CL1= CL2= 100pF (Note 5) Driver Rise or Fall Time tR, tF Figures 4, 6; RDIFF= 54Ω, 15 50 ns CL1= CL2= 100pF Driver Enable to Output High tZH Figures 5, 7; CL= 100pF, S2 closed 0.5 1.8 µs Driver Enable to Output Low tZL Figures 5, 7; CL= 100pF, S1 closed 0.5 1.8 µs Driver Disable Time from High tHZ Figures 5, 7; CL= 15pF, S2 closed 0.6 1.8 µs Driver Disable Time from Low tLZ Figures 5, 7; CL= 15pF, S1 closed 0.6 1.8 µs Receiver Input to Output tPLH Figures 4, 8; RDIFF= 54Ω, 100 225 ns Propagation Delay tPHL CL1= CL2= 100pF 120 225 tPLH- tPHLDifferential tSKD Figures 4, 8; RDIFF= 54Ω, 20 100 ns Receiver Skew CL1= CL2= 100pF Maximum Data Rate fMAX tSKEW, tSKD≤25% of data period 2.5 Mbps _______________________________________________________________________________________ 3

±15kV ESD-Protected, Isolated, 3.3V RS-485/RS-422 Data Interfaces B SWITCHING CHARACTERISTICS—MAX3480EB E (VCC = VCC1 = VCC2 = VCC4 =VCC5 =+3.0V to +3.6V, FS= 0, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC= +3.3V and TA= +25°C.) 0 8 PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 4 Driver Input to Output tPLH Figures 4, 6; RDIFF= 54Ω, 1.5 3.0 µs 3 Propagation Delay tPHL CL1= CL2= 100pF 1.2 3.0 X Figures 4, 6; RDIFF= 54Ω, A Driver Output Skew tSKEW CL1= CL2= 100pF 300 1200 ns M Figures 4, 6; RDIFF= 54Ω, Driver Rise or Fall Time tR, tF CL1= CL2= 100pF 1.0 2.0 µs / A Driver Enable to Output High tZH Figures 5, 7; CL= 100pF, S2 closed 1.2 4.5 µs E Driver Enable to Output Low tZL Figures 5, 7; CL= 100pF, S1 closed 1.0 4.5 µs 0 Driver Disable Time from Low tLZ Figures 5, 7; CL= 15pF, S1 closed 1.5 4.5 µs 8 Driver Disable Time from High tHZ Figures 5, 7; CL= 15pF, S2 closed 2.0 4.5 µs 4 Receiver Input to Output tPLH Figures 4, 8; RDIFF= 54Ω, 0.6 3.0 µs 3 Propagation Delay tPHL CL1= CL2= 100pF 1.4 3.0 AX RtePcLHeiv- etPr HSLkewDifferential tSKD FCiLg1ur=e sC 4L2, 8=; 1R0D0IFpFF= 54Ω, 750 1500 ns M Maximum Data Rate fMAX tSKEW, tSKD≤25% of data period 160 kbps Note 1: All currents into device pins are positive; all currents out of device pins are negative. All voltages are referenced to logic-side ground (GND1, GND2), unless otherwise specified. Note 2: For DE´and DI´pin descriptions, see the Block Diagram and theTypical Application Circuit(Figure 1 for MAX3480EA/MAX3480EB). Note 3: Shutdown supply current is the current at VCC1when shutdown is enabled. Note 4: Limit guaranteed by applying 1520VRMSfor 1s. Test voltage is applied between all pins on one side of the package to all pins on the other side of the package. For example, between pins 1 and 14, and 15 and 28. Note 5: Applies to peak current. See the Typical Operating Characteristicsand the Applications Informationsection. 4 _______________________________________________________________________________________

±15kV ESD-Protected, Isolated, 3.3V RS-485/RS-422 Data Interfaces __________________________________________Typical Operating Characteristics M (VCC_ = +3.3V, TA= +25°C, Figure 1, unless otherwise noted.) A X DRIVER DIFFERENTIAL OUTPUT VOLTAGE OUTPUT CURRENT OUTPUT CURRENT 3 vs. TEMPERATURE vs. DRIVER OUTPUT HIGH VOLTAGE vs. DRIVER OUTPUT LOW VOLTAGE 4 ERENTIAL OUTPUT VOLTAGE (V) 22222223........34567890 DRLI´ = = 5 H4ΩIGH OR OPEN MAX3480EA/EB toc01 OUTPUT CURRENT (mA) -1-------0345678900000000 MAX3480EA/EB toc02 OUTPUT CURRENT (mA) 1111186684020000000 MAX3480EA/EB toc03 80EA/MA DIFF 2.2 -20 40 X 2.1 -10 20 3 2.0 0 0 -40 -20 0 20 40 60 80 -6 -4 -2 0 2 4 6 0 2 4 6 8 10 12 4 TEMPERATURE (°C) OUTPUT HIGH VOLTAGE (V) OUTPUT LOW VOLTAGE (V) 8 0 RECEIVER OUTPUT LOW VOLTAGE RECEIVER OUTPUT HIGH VOLTAGE vs. TEMPERATURE vs. TEMPERATURE E GE (V) 000...678 MIROE A=S 8UmRAED AT ISO RO DRV MAX3480EA/EB toc04 GE (V) 445...570050 MIROE A=S 8UmRAED AT ISO RO DRV MAX3480EA/EB toc05 B OLTA 0.5 OLTA 4.25 V V W 0.4 H 4.00 OUTPUT LO 00..23 OUTPUT HIG 33..5705 0.1 3.25 0 3.00 -40 -20 0 20 40 60 80 -40 -20 0 20 40 60 80 TEMPERATURE (°C) TEMPERATURE (°C) OUTPUT CURRENT OUTPUT CURRENT vs. RECEIVER OUTPUT LOW VOLTAGE vs. RECEIVER OUTPUT HIGH VOLTAGE 7800 MEASURED AT ISO RO DRV MAX3480EA/EB toc06 7800 MEASURED AT ISO RO DRV MAX3480EA/EB toc07 A) 60 A) 60 m m NT ( 50 NT ( 50 RE RE UR 40 UR 40 C C PUT 30 PUT 30 UT UT O O 20 20 10 10 0 0 0 1.0 2.0 3.0 4.0 5.0 0 1.0 2.0 3.0 4.0 5.0 OUTPUT LOW VOLTAGE (V) DIFFERENTIAL OUTPUT VOLTAGE (V) _______________________________________________________________________________________ 5

±15kV ESD-Protected, Isolated, 3.3V RS-485/RS-422 Data Interfaces B Typical Operating Characteristics (continued) E (VCC_ = +3.3V, TA= +25°C, Figure 1, unless otherwise noted.) 0 8 MAX3480EA DRIVER INPUT (AB) MAX3480EA DRIVER ENABLE (AB) MAX3480EA 4 AND RECEIVER OUTPUT (RO) AND RECEIVER OUTPUT (RO) SUPPLY CURRENT vs. SUPPLY VOLTAGE 3 MAX3480EA/EB toc08 MAX3480EA/EB toc09 350 AX D2VI´/ dINivPUT, D1VE/´d IiNvPUT, 300 DE´ HIGH, 50Ω LOAD MAX3480EA/EB toc10 A) 250 M A NT (m DE´ HIGH, 100Ω LOAD A/ B 2V/div A, 1V/div URRE 200 DE´ LOW, DI´ LOW, RL = ∞ C Y 150 E R74OH, C240, B, 2V/div SUPPL 100 DE´ LOW, DI´ HIGH, RL = ∞ 0 2V/div 8 50 4 0 3 100ns/div 100ns/div 3.0 3.2 3.4 3.6 3.8 X CIRCUIT OF FIGURE 2, TERMINATION: 100Ω CIRCUIT OF FIGURE 2, TERMINATION: 100Ω SUPPLY VOLTAGE (V) A MAX3480EB DRIVER INPUT (AB) MAX3480EB DRIVER ENABLE (DE´) MAX3480EB AND RECEIVER OUTPUT (RO) AND DRIVER OUTPUT (AB) SUPPLY CURRENT vs. SUPPLY VOLTAGE M MAX3480EA/EB toc11 MAX3480EA/EB toc12 300 D2VI´/ dINivPUT, D1VE/´d iv 250 DE´ HIGH, 50Ω LOAD MAX3480EA/EB toc13 A 2V/div NT (mA) 200 1D0E0´Ω H LIGOHAD, E R B A UR 150 2V/div LY C DE´ LOW, DI´ LOW, RL = ∞ P B P 100 U 2V/div S DE´ LOW, DI´ HIGH, RL = ∞ RO, 50 74HC240, 2V/div 0 1µs/div 20µs/div 3.0 3.2 3.4 3.6 3.8 SUPPLY VOLTAGE (V) DRIVER ENABLE TIME DRIVER ENABLE TIME vs. TEMPERATURE vs. TEMPERATURE µME (s) 22..05 MAX3480EB MAX3480EA/EB toc14 µME (s) 12..50 MAX3480EB MAX3480EA/EB TOC15 DRIVER ENABLE TI 11..50 RMTOLE =AV SA5U4LΩIRDE, DOD UFI´TR P=OU M0T DE´ DRIVER ENABLE TI 1.0 DRLE ´= T5O4Ω VA, DLIID´ =O U0VT PMUETASURED FROM 0.5 MAX3480EA MAX3480EA 0 0.5 -40 -20 0 20 40 60 80 -40 -20 0 20 40 60 80 TEMPERATURE (°C) TEMPERATURE (°C) 6 _______________________________________________________________________________________

±15kV ESD-Protected, Isolated, 3.3V RS-485/RS-422 Data Interfaces ______________________________________________________________Pin Description M A PIN NAME FUNCTION X PINS ON THE NONISOLATED SIDE 1 VCC1 Logic-Side (Nonisolated Side) +3.3V Supply Voltage Input. Connect to pins 2, 10, and 14. 3 2 VCC2 Logic-Side (Nonisolated Side) +3.3V Supply Voltage Input. Connect to pins 1, 10, and 14. 4 8 3, 4 D1, D2 Boost-Voltage Generator Outputs. See Figures 1 and 2. 0 GND1, 5, 12 Logic-Side Ground Inputs. Must be connected; not internally connected. E GND2 A Frequency Switch Input. If VFS = VCC, switch frequency is high; if FS = 0, switch frequency is low 6 FS (normal connection). / M 7 SD Power-Supply Shutdown Input. Must be connected to logic ground. A 8 VCC3 Boosted V+ Voltage Input. Must be connected as shown in Figures 1 and 2. X Driver Input. With DE´ high, a low on DI´ forces output A low and output B high. Similarly, a high on 9 DI 3 DI´ forces output A high and output B low. Drives internal LED cathode through R1 (Table 1). 4 10 VCC4 Logic-Side (Nonisolated Side) +3.3V Supply Voltage Input. Connect to pins 1, 2, and 14. 8 Driver-Enable Input. The driver outputs, A and B, are enabled by bringing DE´ high. The driver 0 outputs are high impedance when DE´ is low. If the driver outputs are enabled, the device functions E 11 DE as a line driver. While the driver outputs are high impedance, the device functions as a line receiver. B Drives internal LED cathode through R2 (Table 1). Receiver Output. If A > B by 200mV, RO is low; if A < B by 200mV, RO is high. Open collector; must 13 RO have pullup (R3) to VCC (Table 1). 14 VCC5 Logic-Side (Nonisolated Side) +3.3V Supply Voltage Input. Connect to pins 1, 2, and 10. _______________________________________________________________________________________ 7

±15kV ESD-Protected, Isolated, 3.3V RS-485/RS-422 Data Interfaces B _________________________________________________Pin Description (continued) E PIN NAME FUNCTION 0 PINS ON THE ISOLATED RS-485/RS-422 SIDE 8 4 ISO RO Isolated Receiver-Output LED Anode (Input). If A > B by 200mV, ISO RO LED is high; if A < B by 15 LED 200mV, ISO RO LED is low. 3 X 16 ISO COM2 Isolated-Supply Common Input. Connect to ISO COM1. Isolated Driver-Enable Drive Input. The driver outputs, A and B, are enabled by bringing DE´ high. A The driver outputs are high impedance when DE´ is low. If the driver outputs are enabled, the M 17 ISO DE device functions as a line driver. While the driver outputs are high impedance, the device functions DRV as a line receiver. Open collector output; must have pullup (R4 in Figure 1) to ISO VCC and be / A connected to ISO DE IN for normal operation (Table 1). E 18 ISO VCC2 Isolated-Supply Positive Input Voltage. Connect to ISO VCC1. 0 Isolated Driver-Input Drive. With DE´ high, a low on DI´ forces output A low and output B high. 8 19 ISO DI DRV Similarly, a high on DI´ forces output A high and output B low. Open-collector output; must have 4 pullup (R5 in Figure 1) to ISO VCC and be connected to ISO DI IN for normal operation (Table 1). 3 Isolated-Supply Common Output. Connect to ISO COM2. If RS-485 wires have a shield, connect 20 ISO COM1 X ISO COM1 to shield through 100Ω resistor. A 21 ISO DE IN Isolated Driver-Enable Input. Connect to ISO DE DRV for normal operation. M 22 ISO DI IN Isolated Driver Input. Connect to ISO DI DRV for normal operation. 23 A Noninverting Driver Output and Noninverting Receiver Input 24 ISO RO DRV Isolated Receiver-Output Drive. Connect to ISO RO LED through R6 (Table 1 and Figure 1). 25 B Inverting Driver Output and Inverting Receiver Input 26 ISO VCC1 Isolated Supply Positive Output Voltage. Connect to ISO VCC2. 27, 28 AC2, AC1 Internal Connections. Leave these pins unconnected. Note: For DE´and DI´pin descriptions, see Detailed Block Diagram. 8 _______________________________________________________________________________________

±15kV ESD-Protected, Isolated, 3.3V RS-485/RS-422 Data Interfaces _______________Detailed Description isolation barrier (Figure 1). Power is transferred from the M logic side (nonisolated side) to the isolated side of the The MAX3480EA/MAX3480EB are electrically isolated, barrier through a center-tapped transformer. Signals A RS-485/RS-422 data-communications interface solu- cross the barrier through high-speed optocouplers. A X tions. Transceivers, optocouplers, a power driver, and a single +3.3V supply on the logic side powers both transformer are in one standard 28-pin PDIP package. 3 sides of the interface. Signals and power are internally transported across the 4 8 VCC3 ISO VCC1 0 E MAX845 D1 MAX3480EA: MAX485E Q MAX3480EB: MAX487E A N ISO DI IN B FS 1.1OMSHCz/ T F/F D /M 1.6MHz ISO DE IN A D2 Q N A ISO RO DRV R X RE 3 SD GND1 ISO COM1 4 8 0 EXTERNAL RS-485/RS-422 WIRING E TERMINATING RESISTOR MAX3480EA/EB (ONE RESISTOR ON EACH END) B VIN VCC1 1 28 AC1 (MAKE NO CONNECTION) TWISTED PAIR +3.0V TO +3.6V C1 C2 D1, D2 VCC2 2 27 AC2 (MAKE NO CONNECTION) TO OTHER TRANSCEIVERS 22µF 0.1µF 1N914 D1 3 26 ISO VCC1 B RL D2 B 4 25 BOOSTED V+ R7* SHIELD (OPTIONAL) C3 GND1 5 24 ISO RO DRV 0.01µF FS 6 MAX845 MMAAXX1448877EE 23 A A TO OTTHWERIS TTREADN PSACIREIVERS SD 7 22 ISO DI IN R6* SH RL VCC3 8 21 ISO DE IN DI´ R1* DI 9 20 ISO COM1 R4* SHIELD (OPTIONAL) VCC4 10 19 ISO DI DRV R5* R2* LOI/GOIC DE´ DE 11 18 ISO VCC2 R8 NMOATXE34: 8 R0EES FIRSOTOMR T RR8A PNRSOIETNETCTS THE GND2 12 17 ISO DE DRV 100Ω CURRENTS BETWEEN SHIELD AND A AND B. RO ISO COM2 RO 13 16 R3* VCC5 ISO RO LED 14 15 ISOLATION BARRIER ISOLATION COMMON C4 *SEE TABLE 1. LOGIC GROUND 270pF 4kV Figure 1. Block Diagram Table 1. Pullup and LED Drive Resistors PART R1 (Ω) R2 (Ω) R3 (Ω) R4 (Ω) R5 (Ω) R6 (Ω) R7 (Ω) MAX3480EA 100 100 680 3600 1000 200 Open MAX3480EB 100 100 2000 3600 3600 200 430 _______________________________________________________________________________________ 9

±15kV ESD-Protected, Isolated, 3.3V RS-485/RS-422 Data Interfaces B The MAX3480EB features reduced-slew-rate drivers shutdown circuitry that puts the driver outputs into a that minimize EMI and reduce reflections caused by high-impedance state. The receiver input has a fail-safe E improperly terminated cables, allowing error-free trans- feature that guarantees a logic-high output if the input 0 mission at data rates up to 160kbps. The MAX3480EA’s is open circuit. 8 driver slew rates are not limited, allowing transmission The driver outputs are enabled by bringing DE´ high. 4 rates up to 2.5Mbps. Driver-enable times are typically 500ns for the 3 The frequency-select FS is connected to GND_ in normal MAX3480EA and 1µs for the MAX3480EB. Allow time X operation, which selects a switching frequency of for the devices to be enabled before sending data. approximately 600kHz. Connect to high for a higher When enabled, driver outputs function as line drivers. A 900kHz switching frequency. Driver outputs are high impedance when DE´ is low. M While outputs are high impedance, they function as line Drivers are short-circuit current limited and are protect- receivers. ed against excessive power dissipation by thermal / A E 0 8 EXTERNAL RS-485/RS-422 WIRING 4 TERMINATING RESISTOR 3 MAX3480EA/EB (ONE RESISTOR ON EACH END) X VIN VCC1 1 28 AC1 (MAKE NO CONNECTION) A +3.0V TO +3.6V C221µF C0.21µF D11N,9 D124 VCC2 2 27 AC2 (MAKE NO CONNECTION) TO OTTHWERIS TTREADN PSACIREIVERS 6V D1 3 26 ISO VCC1 B RL M D2 4 25 B BOOSTED V+ R7* SHIELD (OPTIONAL) C3 GND1 5 24 ISO RO DRV 74HC240 4 16 0.01µF FS 6 MAX845 MMAAXX1448877EE 23 A A TO OTTHWERIS TTREADN PSACIREIVERS SD 7 22 ISO DI IN R6* SH RL 6 14 VCC3 8 21 ISO DE IN 18 R1* DI 2 8 12 DRIVER INPUT DI 9 20 ISO COM1 R4* SHIELD (OPTIONAL) DE 17 3 15 5 VCC4 10 19 ISO DI DRV R5* 13 7 DRIVER ENABLE DE 11 18 ISO VCC2 R8 NTHOET ME:A XR3E4S8IS0TEO FRR ORM8 P TRROATNESCIETNST R2* GND2 12 17 ISO DE DRV 100Ω CURRENTS BETWEEN SHIELD AND A AND B. 20 RO 13 16 ISO COM2 RO 9 11 RECEIVER OUTPUT R3* VCC5 14 15 ISO RO LED 10 ISOLATION BARRIER ISOLATION COMMON *SEE TABLE 1. C4 LOGIC GROUND 270pF 4kV Figure 2. Typical Application Circuit 10 ______________________________________________________________________________________

±15kV ESD-Protected, Isolated, 3.3V RS-485/RS-422 Data Interfaces _________________________________________________________________Test Circuits M A ISOLATION BARRIER ISOLATION BARRIER X +3.3V A +3.3V 3 R DE´ CL1 A R3 4 A 8 VOD DI´ D VID RDIFF R RO 0 B B E R VOC CL2 A B / M A Figure 3. Driver DC Test Load Figure 4. Driver/Receiver Timing Test Circuit X 3 4 8 0 ISO VCC1, E 500Ω S1 ISO VCC2 B OUTPUT UNDER TEST CL S2 Figure 5. Driver Timing Test Load _______________________________________________________Switching Waveforms VCCD_ I-´ 0.4VVCC_ 2- 0.4V VCC_ 2- 0.4V VDCEC´_ - 00.4VVCC_ 2- 0.4V VCC_ 2- 0.4V 0 tPLH tPHL 1/2 VO tZL tLZ A, B B VO VOL 2.3V OUTPUT NORMALLY LOW VOL + 0.5V A 1/2 VO VDIFF = VA - VB A, B OUTPUT NORMALLY HIGH VO 2.3V VOH - 0.5V VDIFF 0 90% 90% 0 10% 10% -VO tZH tHZ tR tF tSKEW = | tPLH - tPHL | Figure 6. Driver Propagation Delays and Transition Times Figure 7. Driver Enable and Disable Times ______________________________________________________________________________________ 11

±15kV ESD-Protected, Isolated, 3.3V RS-485/RS-422 Data Interfaces B __Switching Waveforms (continued) The MAX3480EA/MAX3480EB withstand 1260VRMS E (1 min) or 1560VRMS(1s). The isolated outputs of these devices meet all RS-485/RS-422 specifications. 0 Boost Voltage 8 The MAX3480EA/MAX3480EB require external diodes 4 on the primary of the transformer to develop the boost 3 VOH voltage for the power oscillator. In normal operation, X RO VOL 1.5V OUTPUT 1.5V whenever one of the oscillator outputs (D1 and D2) A goes low, the other goes to approximately double the M VB - VA -VVIIDD 0 tPHLINPUT tPLH 0 souuptppulyts v oclatang eb.e S cinocme bthinee cdir cwuiitth i sd sioymdemse, tfriilctearl,e tdh,e atwndo / used to power the oscillator itself. A tSKD = |tPLH - tPHL| The diodes on the primary side may be any fast-switch- E ing, small-signal diodes, such as the 1N914, 1N4148, 0 or CMPD2838. The nominal value of the primary filter 8 capacitor C3 is 0.01µF. Figure 8. Receiver Propagation Delays 4 Driver Output Protection 3 There are two mechanisms to prevent excessive output X Function Tables current and power dissipation caused by faults or by bus contention. A foldback current limit on the output A Table 2. Transmitting stage provides immediate protection against short cir- M cuits over the whole common-mode voltage range (see the Typical Operating Characteristics). In addition, a INPUTS OUTPUTS thermal shutdown circuit forces the driver outputs into DE´ DI´ B A a high-impedance state if the die temperature rises excessively. 1 1 0 1 Resistor R8 (Figures 1 and 2) provides additional pro- 1 0 1 0 tection by current limiting between the shield and the two signal wires. In the event that shielded cable is High High 0 X used and an external voltage or transient is inadver- Impedance Impedance tently applied between the shield and the signal wires, X = Don’t care. the MAX3480EA/MAX3480EB can be damaged. Although unlikely, this condition can occur during installation. Table 3. Receiving The MAX3480EA/MAX3480EB provide electrical iso- lation between logic ground and signal paths; they INPUTS OUTPUT do not provide isolation from external shields and DE´ A-B –R—O– the signal paths. When in doubt, do not connect the shield. The MAX3480EA/MAX3480EB can be dam- 0 ≥+0.2V 0 aged if resistor R8 is shorted out. 0 ≤-0.2V 1 Applications Information 0 Inputs open 0 The MAX3480EA/MAX3480EB provide extra protection against ESD. The MAX3480EA/MAX3480EB are intend- ed for harsh environments where high-speed commu- nication is important. These devices eliminate the need for transient suppressor diodes or the use of discrete protection components. The standard (non-E) MAX3480A/MAX3480B are recommended for applica- tions where cost is critical. 12 ______________________________________________________________________________________

±15kV ESD-Protected, Isolated, 3.3V RS-485/RS-422 Data Interfaces M RC RD A 1MΩ 1500Ω IP 100% Ir PEAK-TO-PEAK RINGING X CHARGE-CURRENT DISCHARGE 90% (NOT DRAWN TO SCALE) 3 LIMIT RESISTOR RESISTANCE AMPERES 4 HIGH- DEVICE 8 VOLTAGE Cs STORAGE UNDER 36.8% DC 100pF CAPACITOR TEST 0 SOURCE 10% E 0 0 TIME A tRL tDL / M CURRENT WAVEFORM A X Figure 9. Human Body ESD Test Model Figure 10. Human Body Model Current Waveform 3 4 ±15kV ESD Protection 100pF capacitor charged to the ESD voltage of interest, 8 As with all Maxim devices, ESD-protection structures which is then discharged into the test device through a 0 are incorporated on all pins to protect against electro- 1.5kΩresistor. E static discharges encountered during handling and Machine Model B assembly. The driver outputs and receiver inputs have The Machine Model for ESD tests all pins using a 200pF extra protection against static electricity. Maxim’s engi- storage capacitor and zero discharge resistance. Its neers developed state-of-the-art structures to protect objective is to simulate the stress caused by contact that these pins against ESDof ±15kV without damage. The occurs with handling and assembly during manufactur- ESD structures withstand high ESD in all states: normal ing. Of course, all pins require this protection during operation, shutdown, and power-down. After an ESD manufacturing—not just inputs and outputs. Therefore, event, Maxim’s MAX3480EA/MAX3480EB keep working after PC board assembly, the Machine Model is less rel- without latchup. An isolation capacitor of 270pF 4kV evant to l/O ports. should be placed between ISO COM and logic ground The MAX3480EA/MAX3480EB are designed for bidirec- for optimal performance against an ESD pulse with tional data communications on multipoint bus-transmis- respect to logic ground. sion lines. Figure 11 shows a typical network application circuit. To minimize reflections, terminate the line at both ESD protection can be tested in various ways; the ends with its characteristic impedance, and keep stub transmitter outputs and receiver inputs of this product lengths off the main line as short as possible. The slew- family are characterized for protection to ±15kV using rate-limited MAX3480EB is more tolerant of imperfect ter- the Human Body Model. mination and stubs off the main line. ESD Test Conditions The MAX3480EA/MAX3480EB are specified and char- acterized using the resistor values shown in Table 1. The +15kV ESD test specifications apply only to the A, B, Altering the recommended values can degrade perfor- Y, and Z I/O pins. The test surge may be referenced to mance. either the ISO COM or to the nonisolated GND (this pre- supposes that a bypass capacitor is installed between The DI and DE inputs are the cathodes of LEDs whose VCC2and the nonisolated GND). anodes are connected to VCC. These points are best driven by a +3.3V CMOS-logic gate with a series Human Body Model resistor to limit the current. The resistor values shown Figure 9 shows the Human Body Model, and Figure 10 in Table 1 are recommended when the 74HC240 gate shows the current waveform it generates when dis- or equivalent is used. DI and DE are intended to be charged into a low impedance. This model consists of a ______________________________________________________________________________________ 13

±15kV ESD-Protected, Isolated, 3.3V RS-485/RS-422 Data Interfaces B driven through a series current-limiting resistor. closely represent those of discrete optocouplers, rather Directly grounding these pins destroys the device. than the more robust characteristics of monolithic sili- E con ICs. The reliability testing programs for these multi- 0 Reliability component devices may be viewed on the Maxim 8 These products contain transformers, optocouplers, website (www.maxim-ic.com) under Technical Support, 4 and capacitors, in addition to several monolithic ICs Technical Reference, Multichip Products. 3 and diodes. As such, the reliability expectations more X A Table 4. Maxim’s ±15kV ESD-Protected Isolated RS-485 Product Family M GUARANTEED SUPPLY / NO. OF FULL/HALF SLEW-RATE NO. OF Tx/Rx A PART DATA RATE VOLTAGE Tx/Rx DUPLEX LIMITED ON BUS (Mbps) (V) E MAX1480EA 1/1 2.50 Half No 128 5.0 0 MAX1480EC 1/1 0.25 Half Yes 128 5.0 8 MAX1490EA 1/1 2.50 Full No 32 5.0 4 3 MAX1490EB 1/1 0.25 Full Yes 32 5.0 X MAX3480EA 1/1 2.50 Half No 128 3.3 A MAX3480EB 1/1 0.25 Half Yes 128 3.3 M 14 ______________________________________________________________________________________

±15kV ESD-Protected, Isolated, 3.3V RS-485/RS-422 Data Interfaces M TERMINATING RESISTOR A (ONE RESISTOR ON EACH END) X B 3 DI D 4 120Ω DE 8 A 0 A B A B R RO E A RE / RE R RE R M D D A X RO DE DI RO DE DI 3 4 8 0 E B TERMINATING RESISTOR MAX3480EA/EB (ONE RESISTOR ON EACH END) VIN VCC1 1 28 AC1 (MAKE NO CONNECTION) +3.0V TO +3.6V22Cµ1F 0.C1µ2F D1, D2 VCC2 2 27 AC2 (MAKE NO CONNECTION) 6V 1N914 D1 3 26 ISO VCC1 B D2 4 25 B BOOSTED V+ R7* C3 GND1 5 24 ISO RO DRV 120Ω 0.01µF FS MAX845 MAX1487E A A 6 MAX487E 23 74HC240 4 16 SD 7 22 ISO DI IN R6* SH 6 14 VCC3 8 21 ISO DE IN R4* S(OHPIETLIODNAL) 18 R1* DI 2 8 12 DRIVER INPUT DI 9 20 ISO COM1 DE 17 3 15 5 DRIVER ENABLE R2* VCDCE4 1101 1198 IISSOO DVCI CD2RV R5* 13 7 R8 GND2 ISO DE DRV 12 17 100Ω 20 RO ISO COM2 13 16 RO 9 11 RECEIVER OUTPUT R3* VCC5 14 15 ISO RO LED NOTE: RESISTOR R8 PROTECTS THE MAX3480E 10 ISOLATION BARRIER ISOLATION FROM TRANSIENT COMMON CURRENTS BETWEEN SHIELD AND A AND B. *SEE TABLE 1. C4 270pF LOGIC GROUND 4kV Figure 11. Typical RS-485/RS-422 Network ______________________________________________________________________________________ 15

±15kV ESD-Protected, Isolated, 3.3V RS-485/RS-422 Data Interfaces B Package Information E (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.) 0 8 S 4 EP W. 3 N D1 INCHES MILLIMETERS DIP X DIM MIN MAX MIN MAX P A - 0.200 - 5.08 A A1 0.015 - 0.39 - A2 0.125 0.175 3.18 4.45 M A3 0.055 0.080 1.40 2.03 B 0.016 0.020 0.41 0.51 / A B1 0.045 0.065 1.14 1.65 1 C 0.008 0.012 0.21 0.30 E D1 0.005 0.009 0.13 0.22 TOP VIEW E 0.600 0.625 15.24 15.87 0 E1 0.525 0.575 13.34 14.61 8 e 0.100 BSC 2.54 BSC eA 0.600 BSC 15.24 BSC 4 E eB - 0.700 - 17.78 3 D E1 L 0.120 0.150 3.05 3.81 X A1 A3 A A2 VARIATIONS: A INCHES MILLIMETERS L 0∞-15∞ M DIM MIN MAX MIN MAX N MS011 e B1 C D 1.230 1.270 31.24 32.26 24 AA B eA D 1.430 1.470 36.32 37.34 28 AB eB D 2.025 2.075 51.44 52.71 40 AC FRONT VIEW SIDE VIEW PROPRIETARY INFORMATION TITLE: PACKAGE OUTLINE, .600" PDIP APPROVAL DOCUMENT CONTROL NO. REV. 1 21-0044 B 1 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. 16 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2006 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.