EVALUATION KIT AVAILABLE MAX3535E/MXL1535E LE AVAILAB +3V to +5V, 2500VRMS Isolated RS-485/RS-422 Transceivers with ±15kV ESD Protection General Description The MAX3535E/MXL1535E isolated RS-485/RS-422 fullduplex transceivers provide 2500VRMS of galvanic isolation between the RS-485/RS-422 side and the processor or control logic side. These devices allow fast, 1000kbps communication across an isolation barrier when the common-mode voltages (i.e., the ground potentials) on either side of the barrier are subject to large differences. Isolation is achieved through integrated high-voltage capacitors. The MAX3535E/MXL1535E also feature a 420kHz transformer driver that allows power transfer to the RS-485 side using an external transformer. The MAX3535E/MXL1535E include one differential driver, one receiver, and internal circuitry to send the RS-485 signals and control signals across the isolation barrier (including the isolation capacitors). The MAX3535E/ MXL1535E RS-485 receivers are 1/8 unit load, allowing up to 256 devices on the same bus. The MAX3535E/MXL1535E feature true fail-safe circuitry. The driver outputs and the receiver inputs are protected from ±15kV electrostatic discharge (ESD) on the interface side, as specified in the Human Body Model (HBM). The MAX3535E/MXL1535E feature driver slew-rate select that minimizes electromagnetic interference (EMI) and reduces reflections. The driver outputs are short-circuit and overvoltage protected. Other features are hotswap capability and isolation-barrier fault detection. The MAX3535E operates with a single +3V to +5.5V power supply. The improved secondary supply range of Functional Diagrams the MAX3535E allows the use of step-down transformers for +5V operation, resulting in considerable power savings. The MXL1535E operates with a single +4.5V to +5.5V power supply. The MXL1535E is a function-/pincompatible improvement of the LTC1535. The MAX3535E/MXL1535E are available over the commercial 0°C to +70°C and extended -40°C to +85°C temperature ranges. Applications Isolated RS-485 Systems Features ♦ 2500VRMS RS-485 Bus Isolation Using On-Chip High-Voltage Capacitors ♦ 1000kbps Full-Duplex RS-485/RS-422 Communication ♦ +3V to +5.5V Power-Supply Voltage Range (MAX3535E) ♦ +4.5V to +5.5V Power-Supply Voltage Range (MXL1535E) ♦ 1/8 Unit Receiver Load, Allowing 256 Devices on Bus ♦ ±15kV ESD Protection Using HBM ♦ Pin-Selectable Slew-Rate Limiting Controls EMI ♦ Hot-Swap-Protected Driver-Enable Input ♦ Undervoltage Lockout ♦ Isolation-Barrier Fault Detection ♦ Short-Circuit Protected ♦ Thermal Shutdown ♦ Open-Line and Shorted-Line Fail-Safe Receiver Inputs Ordering Ordering Information Information PART MAX3535ECWI MAX3535EEWI MXL1535ECWI MXL1535EEWI TEMP RANGE PINPACKAGE POWERSUPPLY RANGE (V) 0°C to +70°C 28 Wide SO +3.0 to +5.5 28 Wide SO +3.0 to +5.5 28 Wide SO +4.5 to +5.5 28 Wide SO +4.5 to +5.5 -40°C to +85°C 0°C to +70°C -40°C to +85°C Pin Configuration TOP VIEW VCC1 1 28 RO1 ST1 2 27 RE ST2 3 26 DE GND1 4 25 DI Systems with Large Common-Mode Voltages Industrial-Control Local Area Networks MAX3535E MXL1535E Telecommunications Systems Typical Application Circuit appears at end of data sheet. Pin Configurations appear at end of data sheet. Functional Diagrams continued at end of data sheet. UCSP is a trademark of Maxim Integrated Products, Inc. GND2 11 18 SLO Z 12 17 RO2 Y 13 16 A 15 B VCC2 14 WIDE SO PINS 5–10 and 19–24 ARE REMOVED FROM THE PACKAGE For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com. 19-3270; Rev 0; 4/04 MAX3535E/MXL1535E +3V to +5V, 2500VRMS Isolated RS-485/RS-422 Transceivers with ±15kV ESD Protection ABSOLUTE MAXIMUM RATINGS Logic Side—All Voltages Referenced to GND1. VCC1 .........................................................................-0.3V to +6V RE, DE, DI.................................................................-0.3V to +6V RO1, ST1, ST2 ..........................................-0.3V to (VCC1 + 0.3V) Isolated Side—All Voltages Referenced to GND2. VCC2 .........................................................................-0.3V to +8V SLO...........................................................-0.3V to (VCC2 + 0.3V) A, B ......................................................................................±14V RO2 .....................-0.3V to the lower of (VCC2 + 0.3V) and +3.4V Y, Z ............................................................................-8V to +13V Digital Outputs Maximum Current RO1, RO2 .....................................................................±20mA Y, Z Maximum Current .............................Short-Circuit Protected ST1, ST2 Maximum Current............................................±300mA Continuous Power Dissipation (TA = +70°C) 28-Pin Wide SO (derate 9.5mW/°C above +70°C) .................................750mW Operating Temperature Range MXL1535ECWI, MAX3535ECWI .........................0°C to +70°C MXL1535EEWI, MAX3535EEWI .......................-40°C to +85°C Junction Temperature ......................................................+150°C Storage Temperature Range .............................-65°C to +150°C Lead Temperature (soldering, 10s) .................................+300°C Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. DC ELECTRICAL CHARACTERISTICS TABLE (MAX3535E) (VCC1 = +3.0V to +5.5V, VCC2 = +3.13V to +7.5V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at VCC1 = +3.3V, VCC2 = +5V, TA = +25°C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 5.5 V 5.9 13 mA LOGIC-SIDE SUPPLY (VCC1, GND1) Logic-Side Supply Voltage Logic-Side Supply Current VCC1 ICC1 3.0 Transformer not driven, ST1 and ST2 unconnected, RE = low, DE = high, fDATA = 0, RO1 = no load VCC1 Undervoltage-Lockout Falling Trip VUVL1 2.53 2.69 2.85 V VCC1 Undervoltage-Lockout Rising Trip VUVH1 2.63 2.80 2.97 V 0.8 V ±2 µA LOGIC INPUTS (DI, DE, RE) Input High Voltage, DE, DI, RE VIH VIH is measured with respect to GND1 Input Low Voltage, DE, DI, RE VIL VIL is measured with respect to GND1 Logic-Side Input Current, DE, DI IINC 2.0 V LOGIC OUTPUTS (RO1, RE) 2 Receiver-Output High Voltage (RO1) VRO1H Receiver-Output Low Voltage (RO1) VRO1L Receiver-Output (RO1) Leakage Current IOZR RE Low Output Current for Fault Detect IOL ISOURCE = 4mA, VCC1 = +4.5V 3.7 ISOURCE = 4mA, VCC1 = +3V 2.4 V ISINK = 4mA, VCC1 = +4.5V 0.4 ISINK = 4mA, VCC1 = +3V 0.4 RE = high, VCC1 = +5.5V, 0 ≤ VRO1 ≤ VCC1 ±1 µA 80 µA RE = +0.4V, fault not asserted 40 60 V Maxim Integrated MAX3535E/MXL1535E +3V to +5V, 2500VRMS Isolated RS-485/RS-422 Transceivers with ±15kV ESD Protection DC ELECTRICAL CHARACTERISTICS TABLE (MAX3535E) (continued) (VCC1 = +3.0V to +5.5V, VCC2 = +3.13V to +7.5V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at VCC1 = +3.3V, VCC2 = +5V, TA = +25°C.) PARAMETER SYMBOL RE High Output Current for Fault Detect CONDITIONS MIN TYP MAX UNITS IOH RE = VCC1 - 0.5V, fault asserted -140 -100 -60 µA fSW ST1, ST2, not loaded 290 460 590 kHz TRANSFORMER DRIVER (ST1, ST2) DC-Converter Switching Frequency (ST1, ST2) DC-Converter Total Impedance ROH + ROL (ST1, ST2) ROHL ST1, ST2 Duty Cycle VCC1 = +4.5V, Figure 13 1.6 2.6 VCC1 = +3V, Figure 13 1.8 2.9 50 56 % 7.50 V ST1, ST2, not loaded 44 Ω ISOLATED-SIDE SUPPLY (VCC2, GND2) Isolated-Side Supply Voltage VCC2 Isolated-Side Supply Current ICC2 3.13 fDATA = 0, SLO floating, RO2 = no load, A, B floating, Figure 1 RL = 27Ω 56 70 RL = ∞ 10 16 mA VCC2 Undervoltage-Lockout Falling Trip VUVL2 2.68 2.85 3.02 V VCC2 Undervoltage-Lockout Rising Trip VUVH2 2.77 2.95 3.13 V 4 V DRIVER OUTPUTS (Y, Z) Driver-Output High Voltage VDOH No load, VDOH is measured with respect to GND2 RL = 50Ω (RS-422), VCC2 = +3.13V, Figure 1 Differential Driver Output VOD Driver Common-Mode Output Voltage VOC Change in Magnitude of Driver Differential Output Voltage for Complementary Output States ΔVOD Change in Magnitude of Driver Common-Mode Output Voltage for Complementary Output States ΔVOC Driver Short-Circuit Output Current Maxim Integrated 2.0 2.35 V RL = 27Ω (RS-485), VCC2 = +3.13V, Figure 1 1.5 RL = 27Ω or 50Ω, VOC is measured with respect to GND2, Figure 1 1.0 1.95 3.0 V RL = 27Ω or 50Ω, Figure 1 ±0.2 V RL = 27Ω or 50Ω, Figure 1 ±0.2 V Driver enabled (DE =1 ) DI = high, VY > -7V DI = low, VZ > -7V -250 IOSD mA Driver enabled (DE =1 ) DI = high, VZ < +12V DI = low, VY < +12V +250 3 MAX3535E/MXL1535E +3V to +5V, 2500VRMS Isolated RS-485/RS-422 Transceivers with ±15kV ESD Protection DC ELECTRICAL CHARACTERISTICS TABLE (MAX3535E) (continued) (VCC1 = +3.0V to +5.5V, VCC2 = +3.13V to +7.5V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C, VCC1 = +3.3V, VCC2 = +5V). PARAMETER SYMBOL CONDITIONS MIN TYP DI = high -7V < VY < min[(VCC2 - 1V) +2V] Driver Short-Circuit Foldback Output Current IOSFD Driver enabled (DE =1) MAX -25 DI = low -7V < VZ < min[(VCC2 - 1V) +2V] DI = high +1V < VZ < +12V UNITS µA +25 DI = low +1V < VY < +12V SLEW-RATE SELECT (SLO) Input High Voltage SLO VIHS VIHS is measured with respect to GND2 Input Low Voltage SLO VILS VILS is measured with respect to GND2 SLO Pullup Resistor RSLO VSLO = +3V 3.0 V 1.0 100 V kΩ RECEIVER INPUTS (A, B) Receiver Input Current IAB Receiver Differential Threshold Voltage VTH Receiver-Input Hysteresis ΔVTH Receiver-Input Resistance RIN Receiver-Input Open Circuit Voltage VA or VB = +12V +125 VA or VB = -7V -100 -7V ≤ VCM ≤ +12V -200 -90 -10 -7V ≤ VCM ≤ +12V, TA = 0°C to +70°C 10 30 70 -7v ≤ VCM ≤ +12V, TA = -40°C to +85°C 5 30 70 -7V ≤ VCM ≤ +12V (Note 1) 96 VOAB 200 2.6 µA mV mV kΩ V RECEIVER OUTPUT (RO2) Receiver-Output (RO2) High Voltage VRO2H ISOURCE = 4mA, VCC2 = +3.13V Receiver-Output (RO2) Low Voltage VRO2L ISINK = 4mA, VCC2 = +3.13V 2.4 V 0.4 V ISOLATION Isolation Voltage (Notes 2, 3) VISO Isolation Resistance RISO Isolation Capacitance CISO ESD Protection 4 60s 2500 1s 3000 TA = +25°C, VISO = 50V (Note 3) 100 TA = +25°C Human Body Model (A, B, Y, Z) VRMS 10,000 MΩ 2 pF ±15 kV Maxim Integrated MAX3535E/MXL1535E +3V to +5V, 2500VRMS Isolated RS-485/RS-422 Transceivers with ±15kV ESD Protection SWITCHING ELECTRICAL CHARACTERISTICS (MAX3535E) (VCC1 = +3.0V to +5.5V, VCC2 = +3.13V to +7.5V, RL = 27Ω, CL = 50pF, TA = -40°C to +85°C, unless otherwise noted. Typical values are at VCC1 = +3.3V, VCC2 = +5V, TA = +25°C.) PARAMETER Data Sample Jitter SYMBOL tJ Maximum Data Rate fDATA Self-Oscillating Frequency fSOS Driver-Differential Output Delay Time tDD Driver-Differential Output Transition Time tTD CONDITIONS MIN Figure 6 TYP MAX UNITS 220 285 ns tJ = 25% of data cell, receiver and driver, SLO = high (Note 4) 877 1136 SLO = high, Figure 5 250 450 SLO = low, Figure 5 200 375 kbps kHz SLO = high, Figures 2, 6 490 855 SLO = low, Figures 2, 6 850 1560 SLO = high, Figures 2, 6 SLO = low, Figures 2, 6 120 30 100 220 1000 ns ns Driver-Output Enable Time tPZL, tPZH SLO = high, DI = high or low, Figures 3, 7 730 1400 ns Driver-Output Disable Time tPHZ, tPLZ SLO = high, DI = high or low, Figures 3, 7 720 1300 ns 855 ns Receiver-Propagation Delay Time to RO1 tPLH1, tPHL1 Figures 4, 8 440 Receiver-Propagation Delay Time to RO2 tPLH2, tPHL2 Figures 4, 8 40 ns RO1, RO2 Rise or Fall Time tR, tF Figures 4, 8 40 ns Receiver-Output Enable Time RO1 tZL,tZH Figures 4, 9 30 ns Receiver-Output Disable Time RO1 tLZ,tHZ Figures 4, 9 30 ns Initial Startup Time (from Internal Communication Fault) (Note 5) 1200 ns Internal Communication Timeout Fault Time (Note 5) 1200 ns Maxim Integrated 5 MAX3535E/MXL1535E +3V to +5V, 2500VRMS Isolated RS-485/RS-422 Transceivers with ±15kV ESD Protection ELECTRICAL CHARACTERISTICS (MXL1535E) (VCC1 = +4.5V to +5.5V, VCC2 = +4.5V to +7.5V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at VCC1 = +5V, VCC2 = +5V, TA = +25°C.) MAX UNITS Logic-Side Supply Voltage PARAMETER VCC1 4.5 5.5 V Isolated-Side Supply Voltage VCC2 4.5 7.5 V Logic-Side Supply Current ICC1 Transformer not driven, ST1 and ST2 unconnected, RE = low, DE = high, fDATA = 0, RO1 = no load 5.9 13 mA 56 70 ICC2 fDATA = 0, SLO floating, RO2 = no load, A, B floating, Figure 1 RL = 27Ω Isolated-Side Supply Current RL = ∞ 10 16 Differential Driver Output Driver Output High Voltage VOD VDOH CONDITIONS MIN TYP mA RL = 50Ω (RS-422), VCC2 = +4.5V, Figure 1 2.0 3.0 RL = 27Ω (RS-485), VCC2 = +4.5V, Figure 1 1.5 2.5 No load, VDOH is measured with respect to GND2 5.0 V 3.0 V VOC Change in Magnitude of Driver Differential Output Voltage for Complementary Output States ΔVOD RL = 27Ω or 50Ω, Figure 1 ±0.2 V Change in Magnitude of Driver Common-Mode Output Voltage for Complementary Output States ΔVOC RL = 27Ω or 50Ω, Figure 1 ±0.2 V Driver Short-Circuit Foldback Output Current RL = 27Ω or 50Ω, VOC is measured with respect to GND2, Figure 1 V Driver Common-Mode Output Voltage Driver Short-Circuit Output Current 6 SYMBOL Driver enabled (DE =1) DI = high, VY > -7V DI = low, VZ > -7V 1.0 -250 mA IOSD Driver enabled (DE =1) DI = high, VZ < +12V DI = low, VY < + 12V +250 Driver enabled (DE =1) DI = high -7V < VY < min[(VCC2 - 1V) +2V] DI = low -7V < VZ < min[(VCC2 - 1V) +2V] -25 IOSFD mA Driver enabled (DE =1) DI = high +1V < VZ < +12V DI = low +1V < VY < +12V +25 Maxim Integrated MAX3535E/MXL1535E +3V to +5V, 2500VRMS Isolated RS-485/RS-422 Transceivers with ±15kV ESD Protection ELECTRICAL CHARACTERISTICS (MXL1535E) (continued) (VCC1 = +4.5V to +5.5V, VCC2 = +4.5V to +7.5V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at VCC1 = +5V, VCC2 = +5V, TA = +25°C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Input High Voltage, DE, DI, RE VIH VIH is measured with respect to GND1 2.0 1.45 V Input High Voltage, SLO VIHS VIHS is measured with respect to GND2 4.0 2.1 V Input Low Voltage, DE, DI, RE VIL VIL is measured with respect to GND1 1.45 0.8 V Input Low Voltage, SLO VILS VILS is measured with respect to GND2 2.1 1.0 V Logic-Side Input Current, DE, DI IINC ±2 µA Receiver Input Current IAB Receiver Differential Threshold Voltage VTH VA or VB = +12V +0.25 VA or VB = -7V -0.20 -7V ≤ VCM ≤ +12V -7V ≤ VCM ≤ +12V, TA = 0°C to +70°C Receiver-Input Hysteresis Receiver-Input Resistance -200 -90 -10 10 30 70 ΔVTH RIN -7V ≤ VCM ≤ +12V, TA = -40°C to +85°C 5 30 70 -7V ≤ VCM ≤ +12V (Note 1) 96 140 200 VOAB Receiver-Output High Voltage (RO1) VRO1H ISOURCE = 4mA, VCC1 = +4.5V Receiver-Output Low Voltage (RO1) VRO1L ISINK = 4mA, VCC1 = +4.5V 0.4 3.7 V 4.3 V IOZ DE = low -7V < VY < +12V, -7V < VZ < +12V ±30 Driver-Output Leakage Current IOZ DE = low -7V < VY < +12V, -7V < VZ < +12V ±30 Receiver-Output (RO2) High Voltage VRO2H ISOURCE = 4mA, VCC2 = +4.5V Receiver-Output (RO2) Low Voltage VRO2L ISINK = 4mA, VCC2 = +4.5V Maxim Integrated ST1, ST2 not loaded 2.8 290 kΩ 2.6 Driver-Output Leakage Current fSW mV mV Receiver-Input Open-Circuit Voltage DC-Converter Switching Frequency (ST1, ST2) mA 0.8 V µA ±100 3.4 µA V 0.4 0.8 V 460 590 kHz 7 MAX3535E/MXL1535E +3V to +5V, 2500VRMS Isolated RS-485/RS-422 Transceivers with ±15kV ESD Protection ELECTRICAL CHARACTERISTICS (MXL1535E) (continued) (VCC1 = +4.5V to +5.5V, VCC2 = +4.5V to +7.5V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at VCC1 = +5V, VCC2 = +5V, TA = +25°C.) PARAMETER 8 SYMBOL TYP MAX UNITS Figure 13 4 6 Ω ROL Figure 13 2.5 5 Ω RE Low Output Current for Fault Detect IOL RE = sink current, RE = +0.4V, fault not asserted -40 -50 -80 µA RE High Output Current for Fault Detect IOH RE = source current, RE = +VCC1 - 0.5V, fault asserted 60 100 140 µA DC-Converter Impedance High ST1, ST2 ROH DC-Converter Impedance Low ST1, ST2 CONDITIONS MIN VCC2 Undervoltage-Lockout Falling Trip VUVL2 2.68 2.85 3.02 V VCC2 Undervoltage-Lockout Rising Trip VUVH2 2.77 2.95 3.13 V VCC1 Undervoltage-Lockout Falling Trip VUVL1 2.53 2.69 2.85 V VCC1 Undervoltage-Lockout Rising Trip VUVH1 2.63 2.80 2.97 V Isolation Voltage (Note 2) VISO SLO Pullup Resistor RSLO 60s 2500 1s 3000 VSLO = +3V VRMS 100 kΩ Maxim Integrated MAX3535E/MXL1535E +3V to +5V, 2500VRMS Isolated RS-485/RS-422 Transceivers with ±15kV ESD Protection SWITCHING ELECTRICAL CHARACTERISTICS (MXL1535E) (VCC1 = +4.5V to +5.5V, VCC2 = +4.5V to +7.5V, RL = 27Ω, CL = 50pF, TA = -40°C to +85°C, unless otherwise noted. Typical values are at VCC1 = +5V, VCC2 = +5V, TA = +25°C.) PARAMETER Data Sample Jitter Max Baud Rate SYMBOL tJ fMAX Driver-Differential Output Delay Time tDD Driver-Differential Output Transition Time tTD CONDITIONS MIN Figure 6 SLO = high, Figure 5, (Note 6) 250 TYP MAX UNITS 220 285 ns 450 kBd SLO = high, Figures 2, 6 430 855 SLO = low, Figures 2, 6 850 1560 SLO = high, VCC2 = +4.5V SLO = low, VCC2 = +4.5V 150 45 100 260 1000 ns ns Driver-Output Enable Time tPZL, tPZH SLO = high, DI = high or low, Figure 3, 7 730 1400 ns Driver-Output Disable Time tPHZ, tPLZ SLO = high, DI = high or low, Figures 3, 7 720 1300 ns 855 ns Receiver-Propagation Delay Time to RO1 tPLH1, tPHL1 Figures 4, 8 440 Receiver-Propagation Delay Time to RO2 tPLH2, tPHL2 Figures 4, 8 40 ns RO1, RO2 Rise or Fall Time tR, tF Figures 4, 8 40 ns Receiver-Output Enable Time RO1 tZL, tZH Figures 4, 9 30 ns Receiver-Output Disable Time RO1 tLZ, tHZ Figures 4, 9 30 ns Initial Startup Time (from Internal Communication Fault) (Note 5) 1200 ns Internal Communication Timeout Fault Time (Note 5) 1200 ns ST1, ST2 Duty Cycle ESD Protection 0°C to +70°C 56 -40°C to +85°C 57 Human Body Model (A, B, Y, Z) ±15 % kV Receiver inputs are 96kΩ minimum resistance, which is 1/8 unit load. 60s test result is guaranteed by correlation from 1s result. VISO is the voltage difference between GND1 and GND2. The maximum data rate is specified using the maximum jitter value according to the formula: data rate = 1 / (4tJ). See the Skew section for more information. Note 5: Initial startup time is the time for communication to recover after a fault condition. Internal communication timeout fault time is the time before a fault is indicated on RE, after internal communication has stopped. Note 6: Bd = 2 bits. Note 1: Note 2: Note 3: Note 4: Maxim Integrated 9 MAX3535E/MXL1535E +3V to +5V, 2500VRMS Isolated RS-485/RS-422 Transceivers with ±15kV ESD Protection Typical Operating Characteristics (VCC1 = +5V, CL = 50pF (Figure 1), unless otherwise noted.) 80 RL = 27Ω 40 60 RL = 60Ω 40 RL = OPEN FIGURE 1 35 60 85 -40 -15 10 35 60 -40 85 -15 10 60 85 TEMPERATURE (°C) TEMPERATURE (°C) VCC2 SUPPLY VOLTAGE vs. TEMPERATURE SELF-OSCILLATION FREQUENCY vs. TEMPERATURE DRIVER DIFFERENTIAL OUTPUT TRANSITION TIME vs. TEMPERATURE 6.0 450 100 RL = 27Ω SLO = VCC2 90 80 RL = 27Ω, VCC1 = +5V 4.5 400 tTD (ns) fSOS (kHz) 70 HALO TGM-240NS 1:1.3:1.3 TRANSFORMER SLO = LOW 60 50 VCC2 = +5V 40 350 30 4.0 RL = 27Ω, VCC1 = +3V (MAX3535E) 3.5 -15 10 35 60 10 FIGURE 5 FIGURES 2, 6 0 250 85 VCC2 = +3.13V (MAX3535E) 20 300 FIGURE 1 3.0 -40 -15 10 35 60 -40 85 -15 10 35 60 TEMPERATURE (°C) TEMPERATURE (°C) TEMPERATURE (°C) DRIVER DIFFERENTIAL OUTPUT TRANSITION TIME vs. TEMPERATURE SWITCHER FREQUENCY vs. TEMPERATURE SWITCHER FREQUENCY vs. SUPPLY VOLTAGE 550 600 600 550 500 400 fSW (kHz) fSW (kHz) 500 500 85 MAX3535E toc09 600 MAX3535E toc08 RL = 27Ω SLO = GND2 MAX3535E toc07 800 700 MAX3535E toc06 VCC1 = VCC2 RL = 27Ω SLO = HIGH MAX3535E toc05 500 MAX3535E toc04 RL = OPEN, VCC1 = +5V 6.5 -40 35 TEMPERATURE (°C) 7.0 VCC2 (V) 30 0 10 VCC2 = +3.13V (MAX3535E) FIGURE 1 FIGURE 1 0 tTD (ns) VCC2 = +3.9V (MAX3535E) 50 40 20 -15 VCC2 = +6V 60 RL = OPEN 20 -40 fDATA = 700kbps SLO = LOW RL = 27Ω 70 ICC2 (mA) RL = 60Ω 5.0 80 RL = 27Ω 60 5.5 HALO TGM-240NS 1:1.3:1.3 TRANSFORMER VCC1 = +3.3V MAX3535E toc03 HALO TGM-250NS 1:1:1 TRANSFORMER ICC1 (mA) ICC1 (mA) 100 MAX3535E toc01 100 80 ICC2 SUPPLY CURRENT vs. TEMPERATURE ICC1 SUPPLY CURRENT vs. TEMPERATURE MAX3535E toc02 ICC1 SUPPLY CURRENT vs. TEMPERATURE 450 450 400 400 350 350 VCC2 = +5V 300 VCC2 = +3.13V (MAX3535E) 200 -40 -15 10 FIGURES 2, 6 35 TEMPERATURE (°C) 10 60 300 300 85 -40 -15 10 35 TEMPERATURE (°C) 60 85 3.0 3.5 4.0 4.5 5.0 5.5 VCC1 (V) Maxim Integrated MAX3535E/MXL1535E +3V to +5V, 2500VRMS Isolated RS-485/RS-422 Transceivers with ±15kV ESD Protection Typical Operating Characteristics (continued) (VCC1 = +5V, CL = 50pF (Figure 1), unless otherwise noted.) 0.4 VCC1 = +3V (MAX3535E) VCC1 = +4.5V VCC1 = +5V 4.0 VCC1 = +4.5V DE = HIGH 3.5 VCC2 = +3.9V (MAX3535E) 2.5 3.5 -15 10 35 VCC2 = +7.5V VCC1 = +3V (MAX3535E) 0.5 ISOURCE = 4mA 0 2.0 85 60 -40 -15 10 35 80 100 120 DRIVER-OUTPUT LOW VOLTAGE vs. DRIVER SINK CURRENT DRIVER DIFFERENTIAL OUTPUT VOLTAGE vs. VCC2 SUPPLY VOLTAGE DE = HIGH 9 VCC2 = +7.5V 2.4 8 7 VCC2 = +3.9V (MAX3535E) 6 5 4 3 2 VCC2 = +7.5V VCC2 = +3.9V (MAX3535E) RL = 27Ω 2.6 VOD (V) VDOL (V) -1 -2 2.8 MAX3535E toc14 MAX3535E toc13 12 11 10 2.0 VCC2 = +3.13V (MAX3535E) 1.8 FIGURE 1 1.6 0 20 2.2 1 -7 40 60 80 100 120 0 20 40 60 80 100 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 120 DRIVER SOURCE CURRENT (mA) DRIVER SINK CURRENT (mA) VCC2 (V) RECEIVER OUTPUT (RO1) VOLTAGE vs. LOAD CURRENT DRIVER DIFFERENTIAL OUTPUT VOLTAGE vs. TEMPERATURE ICC1 SUPPLY CURRENT vs. VCC1 SUPPLY VOLTAGE 4 VOD (V) VCC2 = +6V 3 2 2 1 1 RL = OPEN TRANSFORMER IS NOT DRIVEN 9 8 7 VCC2 = +7.5V 3 MAX3535E toc18 4 10 ICC1 (mA) OUTPUT HIGH, SOURCING RL = 27Ω SLO = GND2 MAX3535E toc17 5 MAX3535E toc16 5 MAX3535E toc15 DRIVER-OUTPUT HIGH VOLTAGE vs. DRIVER SOURCE CURRENT VCC2 = +3.13V (MAX3535E) 0 60 DRIVER DIFFERENTIAL OUTPUT CURRENT (mA) 2 -6 40 TEMPERATURE (°C) DE = HIGH -3 -4 -5 20 0 85 60 TEMPERATURE (°C) 5 4 3 1 0 VCC2 = +3.13V (MAX3535E) 1.0 VCC1 = +5V -40 2.0 1.5 3.0 2.5 0 VDOH (V) 4.5 VOD (V) 0.6 0.2 OUTPUT VOLTAGE (V) 4.0 3.0 VRO1H (V) VRO1L (V) 0.8 5.0 DRIVER DIFFERENTIAL OUTPUT VOLTAGE vs. DIFFERENTIAL OUTPUT CURRENT MAX3535E toc11 ISINK = 4mA MAX3535E toc10 1.0 RECEIVER-OUTPUT (RO1) HIGH VOLTAGE vs. TEMPERATURE MAX3535E toc12 RECEIVER-OUTPUT (RO1) LOW VOLTAGE vs. TEMPERATURE 6 5 4 3 VCC2 = +3.13V (MAX3535E) OUTPUT LOW, SINKING 2 1 FIGURE 1 0 0 0 0 5 10 LOAD CURRENT (mA) Maxim Integrated 15 -40 -15 10 35 TEMPERATURE (°C) 60 85 3.0 3.5 4.0 4.5 5.0 5.5 VCC1 SUPPLY VOLTAGE (V) 11 MAX3535E/MXL1535E +3V to +5V, 2500VRMS Isolated RS-485/RS-422 Transceivers with ±15kV ESD Protection Typical Operating Characteristics (continued) (VCC1 = +5V, CL = 50pF (Figure 1), unless otherwise noted.) RECEIVER (RO1) PROPAGATION DELAY (tPLH1) DRIVER PROPAGATION DELAY (SLO = HIGH) DRIVER PROPAGATION DELAY (SLO = LOW) MAX3535E toc19 MAX3535E toc21 MAX3535E toc20 A-B 1V/div DI 2V/div DI 2V/div Y 2V/div Y 2V/div Z 2V/div Z 2V/div RO 1V/div 100ns/div DRIVER ENABLE TIME PLUS JITTER JITTER vs. TEMPERATURE MAX3535E toc23 MAX3535E toc22 300 280 tJ (ns) 400ns/div 400ns/div DE 2V/div 260 Y 2V/div 240 VCC1 = 3.13V 220 VCC1 = 5.5V 200 -40 -15 10 35 60 200ns/div 85 TEMPERATURE (°C) DRIVER DISABLE TIME PLUS JITTER RECEIVER (RO1) PROPAGATION DELAY (tPHL1) MAX3535E toc24 MAX3535E toc25 DE 2V/div A-B 1V/div Y 2V/div 200ns/div 12 RO 1V/div 100ns/div Maxim Integrated MAX3535E/MXL1535E +3V to +5V, 2500VRMS Isolated RS-485/RS-422 Transceivers with ±15kV ESD Protection Pin Description PIN NAME ISOLATION SIDE FUNCTION 1 VCC1 Logic Logic-Side/Transformer-Driver Power Input. Bypass VCC1 to GND1 with 10µF and 0.1µF capacitors. 2 ST1 Logic Transformer-Driver Phase 1 Power Output. Connect ST1 to isolation-transformer primary to send power to isolation side of barrier. 3 ST2 Logic Transformer-Driver Phase 2 Power Output. Connect ST2 to isolation-transformer primary to send power to isolation side of barrier. 4 GND1 Logic Logic-Side Ground. For isolated operation do not connect to GND2. 5–10, 19–24 — — 11 GND2 Isolated Isolation-Side Ground. For isolated operation do not connect to GND1. 12 Z Isolated RS-485/RS-422 Inverting Driver Output. Output floats when DE is low or in a barrier fault event. (See the Detailed Description section for more information.) 13 Y Isolated RS-485/RS-422 Noninverting Driver Output. Output floats when DE is low or in a barrier fault event. (See the Detailed Description section for more information.) 14 VCC2 Isolated Isolated-Side Power Input. Connect VCC2 to the rectified output of transformer secondary. Bypass VCC2 to GND2 with 10µF and 0.1µF capacitors. 15 B Isolated RS-485/RS-422 Differential-Receiver Inverting Input 16 A Isolated RS-485/RS-422 Differential-Receiver Noninverting Input 17 RO2 Isolated Isolated-Side Receiver Output. RO2 is always enabled. RO2 goes high if A - B > -10mV. RO2 goes low if A - B < -200mV. Fail-safe circuitry causes RO2 to go high when A and B float or are shorted. 18 SLO Isolated Driver Slew-Rate Control Logic Input. Connect SLO to GND2 for data rates up to 400kbps. Connect SLO to VCC2 or leave floating for high data rates. 25 DI Logic Driver Input. Pull DI low (high) to force driver output Y low (high) and driver output Z high (low). 26 DE Logic Driver-Enable Input. The driver outputs are enabled and follow the driver input (DI) when DE is high. When DE is floated, the driver is disabled. DE does not affect whether the receiver is on or off. Removed from Package 27 RE Logic Receiver-Output Enable and Fault Current Output. The receiver output (RO1) is enabled and follows the differential-receiver inputs, A and B, when RE is low, otherwise RO1 floats. RE does not affect RO2 and does not disable the driver. The asserted fault output is a pullup current, otherwise RE shows a pulldown current. 28 RO1 Logic Receiver Output. RO1 is enabled when RE is low. RO1 goes high if A - B > -10mV. RO1 goes low if A - B < -200mV. Fail-safe circuitry causes RO1 to go high when A and B float or are shorted. Maxim Integrated 13 MAX3535E/MXL1535E +3V to +5V, 2500VRMS Isolated RS-485/RS-422 Transceivers with ±15kV ESD Protection Test Circuits Y VCC2 500Ω RL Y/Z VOC VOD 500Ω CL RL GND2 Z Figure 1. Driver DC Test Load Figure 3. Driver Timing Test Load HIGH VCC1/VCC2 RL DE 1kΩ CL Y DI RO1/RO2 1kΩ CL Z RL GND2 CL GND1/GND2 GND Figure 4. Receiver Timing Test Load Figure 2. Driver Timing Test Circuit TGM-240 1/2 BAT54C CONTROL GROUND 0.1μF 10μF RS-485 GROUND 1/2 BAT54C ST1 +3.0V TO +5.5V ST2 VCC1 0.1μF VCC2 GND2 TRANSFORMER DRIVER VOLTAGE REGULATOR 10μF A RO1 B RECEIVER RE RO2 DE DRIVER Y 2RL Z DI GND1 VCC2 MAX3535E BARRIER TRANSCEIVER BARRIER TRANSCEIVER CL CL SLO ISOLATION BARRIER Figure 5. Self-Oscillating Configuration 14 Maxim Integrated MAX3535E/MXL1535E +3V to +5V, 2500VRMS Isolated RS-485/RS-422 Transceivers with ±15kV ESD Protection Switching Waveforms DI tR < 10ns, tF < 10ns 1.5V tR < 10ns, tF < 10ns 1.5V VA - VB 0V 0V INPUT tDD tDD tPHL1 Z tPLH1 tPLH1 VRO1H/2 VRO1H VDOH VRO1H/2 RO1 Y OUTPUT VRO1L 1/2 VDOH RO2 VDOH VOD = VY - VZ 80% 0V 20% -VDOH 80% 80% 80% 20% tTD tJ tJ 20% 20% tPLH2 tPLH2 tTD tF tJ tR Figure 8. Receiver Propagation Delays Figure 6. Driver Propagation Delay tR < 10ns, tF < 10ns DE 1.5V 1.5V RE 1.5V 1.5V tR < 10ns, tF < 10ns tPZL tPLZ VDOH tZL VDOH/2 Y, Z VDOL + 0.5V VRO1L + 0.5V RO1 OUTPUT NORMALLY LOW VDOL OUTPUT NORMALLY LOW VRO1L VDOH VRO1H OUTPUT NORMALLY HIGH Y, Z VDOH - 0.5V VDOH/2 0V tPZH Figure 7. Driver Enable and Disable Times Maxim Integrated OUTPUT NORMALLY HIGH VRO1H - 0.5V RO1 0V tPHZ 2 x tJ tLZ VRO1H tZH tHZ tJ Figure 9. Receiver Enable and Disable Times 15 MAX3535E/MXL1535E +3V to +5V, 2500VRMS Isolated RS-485/RS-422 Transceivers with ±15kV ESD Protection Detailed Description The MAX3535E/MXL1535E isolated RS-485/RS-422 fullduplex transceivers provide 2500VRMS of galvanic isolation between the RS-485/RS-422 isolation side and the processor or logic side. These devices allow fast, 1000kbps communication across an isolation barrier even when the common-mode voltages (i.e., the ground potentials) on either side of the barrier are subject to large differences. The isolation barrier consists of two parts. The first part is a capacitive isolation barrier (integrated highvoltage capacitors) that allows data transmission between the logic side and the RS-485/RS-422 isolation side. Data is sampled and encoded before it is transmitted across the isolation barrier introducing sampling jitter and further delay into the communication system. The second part of the isolation barrier consists of an external transformer with the required primary-to-secondary isolation, allowing the transmission of operating power from the logic side across the isolation barrier to the isolation side. Connect the primary of the external transformer to the MAX3535E/MXL1535E’s 420kHz transformer driver outputs ST1 and ST2. Since the MXL1535E and the MAX3535E operate with different supply-voltage requirements at their respective isolated and logic sides, different isolation transformers must be used with each device (see the Transformer Selection section). The only external components needed to complete the system are the isolation transformer, two diodes, and two low-voltage, 10µF decoupling capacitors (see the Typical Application Circuit). The MAX3535E/MXL1535E include one differential driver, one receiver, and internal circuitry to send the RS485 signals and logic signals across the isolation barrier (including the isolation capacitors). The MAX3535E/ MXL1535E receivers are 1/8 unit load, allowing up to 256 devices on a single bus. The MAX3535E/MXL1535E feature fail-safe circuitry ensuring the receiver output maintains a logic-high state when the receiver inputs are open or shorted, or when connected to a terminated transmission line with all drivers disabled (see the Fail Safe section). The MAX3535E/MXL1535E feature driver slew-rate select that minimizes electromagnetic interference (EMI) and reduces reflections caused by improperly terminated cables at data rates below 400kbps. The 16 driver outputs are short-circuit protected for sourcing or sinking current and have overvoltage protection. Other features include hot-swap capability, which holds the driver off if the driver logic signals are floated after power is applied. The MAX3535E/MXL1535E have error-detection circuitry that alerts the processor when there is a fault and disables the driver until the fault is removed. Fail Safe The MAX3535E/MXL1535E guarantee a logic-high receiver output when the receiver inputs are shorted or open, or when connected to a terminated transmission line with all drivers disabled. The receiver threshold is fixed between -10mV and -200mV. If the differential receiver input voltage (A - B) is greater than or equal to -10mV, RO1 is logic-high (Table 2). In the case of a terminated bus with all transmitters disabled, the receiver’s differential input voltage is pulled to zero by the termination. Due to the receiver thresholds of the MAX3535E/MXL1535E, this results in a logic-high at RO1 with a 10mV minimum noise margin. Driver Output Protection Two mechanisms prevent excessive output current and power dissipation caused by faults or by bus contention. The first, a foldback current limit on the output stage, provides immediate protection against short circuits over the entire common-mode voltage range. The second, a thermal-shutdown circuit, forces the driver outputs into a high-impedance state if the die temperature exceeds +150°C. Monitoring Faults on RE RE functions as both an input and an output. As an input, RE controls the receiver output enable (RO1). As an output, RE is used to indicate when there are faults associated with the operation of the part. This dual functionality is made possible by using an output driver stage that can easily be overdriven by most logic gates. When an external gate is not actively driving RE, it is driven either high using a 100µA internal pullup current (fault present), or low using a 60µA internal pulldown current (no fault). When using RE to control the receiver-enable output function, be sure to drive it using a gate that has enough sink and source capability to overcome the internal drive. Maxim Integrated MAX3535E/MXL1535E +3V to +5V, 2500VRMS Isolated RS-485/RS-422 Transceivers with ±15kV ESD Protection When not actively driving RE, it functions as the fault indicator (Table 3). A low on RE indicates the part is functioning properly, while a high indicates a fault is present. The four causes of a fault indication are: 1) The voltage on VCC1 is below its undervoltage-lockout threshold (2.69V nominal) 2) The voltage on VCC2 is below its undervoltage-lockout threshold (2.80V nominal) 3) There is a problem that prevents the MAX3535E/ MXL1535E from communicating across its isolation barrier 4) The die temperature exceeds +150°C nominally, causing the part to go into thermal shutdown When a fault occurs, RO1 is switched to a logic-high state if RE is low (Table 3). Open-circuit or short-circuit conditions on the receiver inputs do not generate fault conditions; however, any such condition also puts RO1 in a logic-high state (see the Fail Safe section). RO1 D Slew-Rate Control Logic The SLO input selects between a fast and a slow slew rate for the driver outputs. Connecting SLO to GND2 selects the slow slew-rate option that minimizes EMI and reduces reflections caused by improperly terminated cables at data rates up to 400kbps. This occurs because lowering the slew rate decreases the rise and fall times for the signal at the driver outputs, drastically reducing the high-frequency components and harmonics at the output. Floating SLO or connecting it to VCC2 selects the fast slew rate, which allows high-speed operation. VCC1 TRI-STATED BUFFER/ BIDIRECTIONAL MICROCONTROLLER I/O RE Read RE for fault conditions by using a bidirectional microcontroller I/O line or a tri-stated buffer as shown in Figure 10. When using a tri-stated buffer, enable the driver whenever the voltage on RE needs to be forced to a logic-high or logic-low. To read RE for a fault condition, disable the driver. VCC1 RE OE DRIVER OUTPUT BECOMES HIGH IMPEDANCE OE DE MAX3535E MXL1535E FAULT FAULT FAULT DETECTED R DI GND1 Figure 10. Reading a Fault Condition Maxim Integrated 17 MAX3535E/MXL1535E +3V to +5V, 2500VRMS Isolated RS-485/RS-422 Transceivers with ±15kV ESD Protection Functional Tables Table 1. Transmitting Logic TRANSMITTING LOGIC INPUTS OUTPUTS DE DI Y Z 1 1 1 0 1 0 0 1 0 X High impedance High impedance Table 2. Receiving Logic RECEIVING LOGIC INPUTS OUTPUTS RE VA - VB RO1 RO2 0 >-10mV 1 1 0 <-200mV 0 0 0 Inputs open/shorted 1 1 1 >-10mV High impedance 1 1 <-200mV High impedance 0 1 Inputs open/shorted High impedance 1 Table 3. Fault Mode NORMAL MODE FAULT MODES FUNCTION VCC1 > VUVH1 VCC2 > VUVH2 VCC1 < VUVL1 VCC2 > VUVH2 VCC1 > VUVH1 VCC2 < VUVL2 VCC1 < VUVL1 VCC2 < VUVL2 THERMAL SHUTDOWN INTERNAL COMMUNICATION FAULT On On On On Off On RE = 0 Active High High High High High RE = VCC1 High impedance High impedance High impedance High impedance High impedance High impedance RE = floating Active High impedance High impedance High impedance High impedance High impedance RO2 Active Active Active Active Active Active Driver outputs (Y, Z) Active High impedance High impedance High impedance High impedance High impedance Internal barrier communication Active Disabled Disabled Disabled Disabled Communication attempted Fault indicator on RE Low (60µA pulldown) High (100µA pullup) High (100µA pullup) High (100µA pullup) High (100µA pullup) High (100µA pullup) Transformer driver (ST1, ST2) RO1 18 Maxim Integrated MAX3535E/MXL1535E +3V to +5V, 2500VRMS Isolated RS-485/RS-422 Transceivers with ±15kV ESD Protection Applications Information multidrop-network applications circuit. Figure 12 shows the MAX3535E/MXL1535E functioning as line repeaters with cable lengths longer than 4000ft. To minimize reflections, terminate the line at both ends in its characteristic impedance. Keep stub lengths off the main line as short as possible. Typical Applications The MAX3535E/MXL1535E transceivers facilitate bidirectional data communications on multipoint bus transmission lines. Figure 11 shows a typical RS-485 B D 120Ω A A B A DE B R R RE RO R RE RE D RO DE DI D DI RO DE TGM-240 DI 1/2 BAT54C CONTROL GROUND 0.1μF 10μF RS-485 GROUND 1/2 BAT54C ST1 +3.3V ST2 VCC1 0.1μF VCC2 GND2 TRANSFORMER DRIVER VOLTAGE REGULATOR 10μF A RO1 R RECEIVER RE DE DRIVER D DI GND1 B RO2 Y Z 120Ω VCC2 MAX3535E SLO BARRIER TRANSCEIVER BARRIER TRANSCEIVER ISOLATION BARRIER Figure 11. Typical Half-Duplex Multidrop RS-485 Network Maxim Integrated 19 MAX3535E/MXL1535E +3V to +5V, 2500VRMS Isolated RS-485/RS-422 Transceivers with ±15kV ESD Protection 1/2 TGM-250 BAT54C CONTROL GROUND 10μF 0.1μF RS-422 GROUND 1/2 BAT54C VCC2 GND2 ST2 TRANSFORMER DRIVER VOLTAGE REGULATOR A 120Ω B D +5V ST1 VCC1 10μF MAX488 RO1 R DI RECEIVER DE Y DRIVER 120Ω Y D Z RE RO2 R 0.1μF A RO R B D Z DI VCC2 BARRIER TRANSCEIVER SLO MAX3535E BARRIER MXL1535E TRANSCEIVER GND1 ISOLATION BARRIER Figure 12. Using the MAX3535E/MXL1535E as an RS-422 Line Repeater Transformer Selection TRANSFORMER DRIVER OUTPUT STAGE VCC1 ROH ROH ST1 ST2 TRANSFORMER PRIMARY ROL ROL GND1 Figure 13. Transformer Driver Output Stage 20 The MXL1535E is a pin-for-pin compatible upgrade of the LTC1535, making any transformer designed for that device suitable for the MXL1535E (see Table 4). These transformers all have a turns ratio of about 1:1.3CT. The MAX3535E can operate with any of the transformers listed in Table 4, in addition to smaller, thinner transformers designed for the MAX845 and MAX253. The 420kHz transformer driver operates with single primary and center-tapped secondary transformers. When selecting a transformer, do not exceed its ET product, the product of the maximum primary voltage and half the highest period of oscillation (lowest oscillating frequency). This ensures that the transformer does not enter saturation. Calculate the minimum ET product for the transformer primary as: ET = VMAX / (2 x fMIN) where, VMAX is the worst-case maximum supply voltage, and fMIN is the minimum frequency at that supply voltage. Using +5.5V and 290kHz gives a required minimum ET Maxim Integrated MAX3535E/MXL1535E +3V to +5V, 2500VRMS Isolated RS-485/RS-422 Transceivers with ±15kV ESD Protection product of 9.5V-µs. The commercially available transformers for the MAX845 listed in Table 5 meet that requirement. In most cases, use half of the center-tapped primary winding with the MAX3535E and leave the other end of the primary floating. Most of the transformers in Table 5 are 1:1:1 or 1:1:1:1 turns ratio. For +3.3V operation (+3.6V maximum) the required primary ET product is 6.2V-µs. All of the previously mentioned transformers meet this requirement. Table 6 lists some other transformers with step-up turns ratios specifically tailored for +3.3V operation. Most of the transformers in Table 6 are 1:1:1.3:1.3. By using a HALO TGM-010 or Midcom 95061 transformer, it becomes possible to build a complete isolated RS-485/RS-422 transceiver with a maximum thickness less than 0.1in. To minimize power consumption, select the turns ratio of the transformer to produce the minimum DC voltage required at VCC2 (+3.13V) under worst-case, high-temperature, low-VCC1, and full-load conditions. For light loads on the isolated side, ensure that the voltage at VCC2 does not exceed +7.5V. For example, the CTX0114659 transformer results in 85mA (typ) VCC1 supply current with full load on the RS-485 driver. Using a TGM250 1:1:1 transformer lowers the VCC1 supply current to 65mA (typ), while maintaining good margin on the VCC2 supply. A slight step-down transformer can result in extra power savings in some situations. A custom wound sample transformer with 23 primary turns and 20:20 secondary turns on a Ferronics 11-050B core operates well with a VCC1 supply current of 51mA (typ). Table 4. Transformers for the MXL1535E/MAX3535E MANUFACTURER PART NUMBER ISOLATION VOLTAGE (1s) PHONE NUMBER Cooper Electronic Technologies, Inc. CTX01-14659 500V 561-241-7876 Cooper Electronic Technologies, Inc. CTX01-14608 3750VRMS 561-241-7876 B78304-A1477-A3 500V 0 89-626-2-80-00 800-888-7724 31160R 1250V 605-886-4385 EPCOS AG (Germany) (USA) Midcom, Inc. Pulse FEE (France) P1597 500V 33-3-85-35-04-04 Sumida Corporation (Japan) S-167-5779 100V 03-3667-3320 Transpower Technologies, Inc. TTI7780-SM 500V 775-852-0145 Table 5. Transformers for MAX3535E at +5V MANUFACTURER PART NUMBER ISOLATION VOLTAGE (1s) TGM-010 500VRMS TGM-250 2000VRMS TGM-350 3000VRMS TGM-450 4500VRMS BH Electronics, Inc. 500-1749 Coilcraft, Inc. U6982-C HALO Electronics, Inc. Newport/C&D Technologies Midcom, Inc. PCA Electronics, Inc. PHONE NUMBER WEBSITE 650-903-3800 www.haloelectronics.com/6pin.html 3750VRMS 952-894-9590 www.bhelectronics.com/PDFs/DCDCConverterTransformers.pdf 1500VRMS 800-322-2645 44-1236-730595 www.coilcraft.com/minitrans.cfm 520-295-4300 www.dc-dc.com/products/productline.asp?ED=9 7825355 1500V 7625335 4000V 95061 1250V 605-886-4385 www.midcom-inc.com www.pca.com/Datasheets/EPC3117S-X.pdf EPC3115S-5 700V DC 818-894-5791 Rhombus Industries, Inc. T-1110 1800VRMS 714-898-0960 www.rhombus-ind.com/pt-cat/maxim.pdf Premier Magnetics, Inc. PM-SM15 1500VRMS 949-452-0511 www.premiermag.com/pdf/pmsm15.pdf Maxim Integrated 21 MAX3535E/MXL1535E +3V to +5V, 2500VRMS Isolated RS-485/RS-422 Transceivers with ±15kV ESD Protection Table 6. Transformers for MAX3535E at +3.3V MANUFACTURER PART NUMBER ISOLATION VOLTAGE (1s) TGM-040 500VRMS TGM-240 2000VRMS TGM-340 3000VRMS TGM-340 4500VRMS BH Electronics, Inc. 500-2582 Coilcraft, Inc. Q4470-C HALO Electronics, Inc. Newport/C&D Technologies Midcom, Inc. PCA Electronics, Inc. PHONE NUMBER WEBSITE 650-903-3800 www.haloelectronics.com/6pin.html 2000VRMS 952-894-9590 www.bhelectronics.com/PDFs/DCDCConverterTransformers.pdf 1500VRMS 800-322-2645 44-1236-730595 www.coilcraft.com/minitrans.cfm 520-295-4300 www.dc-dc.com/products/productline.asp?ED=9 605-886-4385 www.midcom-inc.com 78253335 1500V 76253335 4000V 95062 1250V 95063 1250V EPC3115S-2 700V DC 818-894-5791 www.pca.com/Datasheets/EPC3117S-X.pdf Rhombus Industries, Inc. T-1107 1800VRMS 714-898-0960 www.rhombus-ind.com/pt-cat/maxim.pdf Premier Magnetics Inc. PM-SM16 1500VRMS 949-452-0511 www.premiermag.com/pdf/pmsm15.pdf ±15kV ESD Protection As with all Maxim devices, ESD-protection structures are incorporated on all pins to protect against electrostatic discharges encountered during handling and assembly. The driver outputs and receiver inputs have extra protection against static electricity. Maxim’s engineers have developed state-of-the-art structures to protect these pins against ESD of ±15kV without damage. The ESD structures withstand high ESD in all states. After an ESD event, the MAX3535E/MXL1535E keep working without latchup. ESD protection can be tested in various ways. The transmitter outputs and receiver inputs of this product family are characterized for protection to ±15kV using the Human Body Model. RC 1MΩ CHARGE-CURRENTLIMIT RESISTOR HIGHVOLTAGE DC SOURCE Cs 100pF RD 1500Ω DISCHARGE RESISTANCE STORAGE CAPACITOR DEVICE UNDER TEST ESD Test Conditions The ±15kV ESD test specifications apply only to the A, B, Y, and Z I/O pins. The test surge is referenced to GND2. All remaining pins are ±2kV ESD protected. Human Body Model Figure 14 shows the Human Body Model, and Figure 15 shows the current waveform it generates when dis- 22 Figure 14. Human Body ESD Test Model charged into low impedance. This model consists of a 100pF capacitor charged to the ESD voltage of interest, which is then discharged into the test device through a 1.5kΩ resistor. Maxim Integrated MAX3535E/MXL1535E +3V to +5V, 2500VRMS Isolated RS-485/RS-422 Transceivers with ±15kV ESD Protection DATA SKEW vs. DATA RATE 50 45 IP 100% 90% PEAK-TO-PEAK RINGING (NOT DRAWN TO SCALE) 40 DATA SKEW (%) Ir AMPERES 36.8% 10% 0 35 30 25 20 15 0 tRL TYP SKEW MAX SKEW 10 TIME 5 tDL CURRENT WAVEFORM 0 0 250 500 750 1000 1250 1500 1750 2000 DATA RATE (kbps) Figure 15. Human Body Current Waveform Figure 16. Data Skew vs. Data Rate Graph Machine Model The Machine Model for ESD tests all pins using a 200pF storage capacitor and zero discharge resistance. Its objective is to simulate the stress caused by contact that occurs with handling and assembly during manufacturing. All pins require this protection during manufacturing, not just inputs and outputs. Therefore, after PC board assembly, the Machine Model is less relevant to I/O ports. Higher rates are possible but with more distortion and jitter. The data rate should always be limited below 1.75Mbps for both receiver and driver to avoid interference with the internal barrier communication. Skew The self-oscillation circuit shown in Figure 5 is an excellent way to get an approximate measure of the speed of the MAX3535E/MXL1535E. An oscillation frequency of 250kHz in this configuration implies a data rate of at least 500kbps for the receiver and transmitter combined. In practice, data can usually be sent and received at a considerably higher data rate, normally limited by the allowable jitter and data skew. If the system can tolerate a 25% data skew, (the difference between tPLH1 and tPHL1), the 285ns maximum jitter specification implies a data rate of 877kbps. Lower data rates result in less distortion and jitter (Figure 16). Maxim Integrated Layout Considerations The MAX3535E/MXL1535E pin configurations enable optimal PC board layout by minimizing interconnection lengths and crossovers: • For maximum isolation, the isolation barrier should not be breached except by the MAX3535E/MXL1535E and the transformer. Connections and components from one side of the barrier should not be located near those of the other side of barrier. • A shield trace connected to the ground on each side of the barrier can help intercept capacitive currents that might otherwise couple into the DI and SLO inputs. In a double-sided or multilayer board, these shield traces should be present on all conductor layers. • Try to maximize the width of the isolation barrier wherever possible. A clear space of at least 0.25in between GND1 and GND2 is recommended. 23 MAX3535E/MXL1535E +3V to +5V, 2500VRMS Isolated RS-485/RS-422 Transceivers with ±15kV ESD Protection Typical Application Circuit TGM-240 1/2 BAT54C CONTROL GROUND 0.1μF 10μF RS-485 GROUND 1/2 BAT54C ST1 +3.3V ST2 VCC1 0.1μF GND2 TRANSFORMER DRIVER VCC2 VOLTAGE REGULATOR 10μF A RO1 B μC RECEIVER RE RO2 DE DRIVER Y Z DI GND1 VCC2 MAX3535E BARRIER TRANSCEIVER BARRIER TRANSCEIVER SLO ISOLATION BARRIER Chip Information PROCESS: BiCMOS TRANSISTOR COUNT: 7379 24 Maxim Integrated MAX3535E/MXL1535E +3V to +5V, 2500VRMS Isolated RS-485/RS-422 Transceivers with ±15kV ESD Protection Package Information 28L 16L SOIC.EPS (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.) Maxim Integrated 25 MAX3535E/MXL1535E +3V to +5V, 2500VRMS Isolated RS-485/RS-422 Transceivers with ±15kV ESD Protection 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. 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. 26 © Maxim Integrated 160 Rio Robles, San Jose, CA 95134 USA 1-408-601-1000 Maxim Integrated The Maxim logo and Maxim Integrated are trademarks of Maxim Integrated Products, Inc.