EVALUATION KIT AVAILABLE MAX14856/MAX14858 5kVRMS Isolated 500kbps/25Mbps Full-Duplex RS-485/RS-422 Transceivers with ±35kV ESD Protection General Description The MAX14856/MAX14858 isolated RS-485/RS-422 transceivers provide 5000VRMS (60s) of galvanic isolation between the cable side (RS-485/RS-422 driver/ receiver-side) and the UART side of the device. Isolation improves communication by breaking ground loops and reduces noise when there are large differences in ground potential between ports. These devices allow for robust communication up to 500kbps (MAX14856) or 25Mbps (MAX14858). The devices include one drive channel and one receive channel. The receiver is 1/4-unit load, allowing up to 128 transceivers on a common bus. Integrated true fail-safe circuitry ensures a logic-high on the receiver output when inputs are shorted or open. Undervoltage lockout disables the driver when the cable side or UART side power supplies are below functional levels. The driver outputs and receiver inputs are protected from ±35kV electrostatic discharge (ESD) to GNDB on the cable side, as specified by the Human Body Model (HBM). The devices are available in a wide-body 16-pin SOIC package and operate over the -40°C to +105°C temperature range. ●● High-Performance Transceiver Enables Flexible Designs • Integrated LDO for Cable Side Power • Compliant with RS-485 EIA/TIA-485 Standard • 500kbps (MAX14856)/25Mbps (MAX14858) Maximum Data Rate • Allows Up to 128 Devices on the Bus ●● Integrated Protection Ensures for Robust Communication • ±35kV ESD (HBM) on Driver Outputs/Receiver Inputs • 5kVRMS Withstand Isolation Voltage for 60 Seconds (VISO) • 1200VPEAK Maximum Repetitive Peak-Isolation Voltage (VIORM) • 848VRMS Maximum Working-Isolation Voltage (VIOWM) • > 30 Years Lifetime at Rated Working Voltage • Withstands ±10kV Surge per IEC 61000-4-5 • Thermal Shutdown Safety Regulatory Approvals Pending ●● UL According to UL1577 ●● cUL According to CSA Bulletin 5A ●● VDE 0884-10 Applications ●● ●● ●● ●● Functional Diagram VDDA Benefits and Features Industrial Automation Equipment Programmable Logic Controllers HVAC Power Meters VLDO LDO MAX14856 MAX14858 VDDB RS-485 TRANSCEIVER SBA RXD RE TXD DE GNDA 19-7966; Rev 0; 11/15 GNDB A B Z Y Ordering Information appears at end of data sheet. MAX14856/MAX14858 5kVRMS Isolated 500kbps/25Mbps Full-Duplex RS-485/RS-422 Transceivers with ±35kV ESD Protection Absolute Maximum Ratings VDDA to GNDA .......................................................-0.3V to +6V VDDB to GNDB........................................................-0.3V to +6V VLDO to GNDB......................................................-0.3V to +16V TXD, DE, RE to GNDA ............................................-0.3V to +6V SBA, RXD to GNDA .............................. -0.3V to (VDDA + 0.3V) A, B, Z, Y to GNDB...................................................-8V to +13V Short Circuit Duration (RXD, SBA to GNDA, A, B, Y, Z ,VDDB to GNDB)....................................Continuous Continuous Power Dissipation (TA = +70°C) 16-pin Wide SOIC (derate 14.1mW/°C above +70°C)........................... 1126.8mW Operating Temperature Range.......................... -40°C to +105°C Junction Temperature.......................................................+150°C Storage Temperature Range............................. -65°C to +150°C Lead Temperature (soldering, 10s).................................. +300°C Soldering Temperature (reflow)........................................ +260°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. Package Thermal Characteristics (Note 1) Junction-to-Ambient Thermal Resistance (θJA)...............71°C/W Junction-to-Case Thermal Resistance (θJC)....................23°C/W Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer board. For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial. DC Electrical Characteristics (VDDA – VGNDA = 1.71V to 5.5V, VDDB – VGNDB = 3.0V to 5.5V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VDDA – VGNDA = 3.3V, VDDB – VGNDB = 3.3V, VGNDA = VGNDB, and TA = +25°C.) (Notes 2, 3) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS POWER Supply Voltage Supply Current Undervoltage-Lockout Threshold Undervoltage-Lockout Threshold Hysteresis VDDA 1.71 5.5 VDDB 3.0 5.5 IDDA VDDA = 5V, DE = high, RE = TXD = low, RXD unconnected, no load 3.9 IDDB DE = high, RE = TXD = low, RXD unconnected, no bus load, VDDB = 3.3V 7 V 6.6 mA 12.5 VUVLOA VDDA rising 1.50 1.58 1.65 VUVLOB VDDB rising 2.55 2.7 2.85 VUVHYSTA 50 VUVHYSTB 200 V mV LDO LDO Supply Voltage VLDO Relative to GNDB, LDO is on (Note 4) LDO Supply Current ILDO DE = high, TXD = low, no bus load, VLDO = 5.5V LDO Output Voltage VDDB 3.18 3.0 LDO Current Limit 14 V 7.5 12.9 mA 3.3 3.6 V 300 Load Regulation VLDO = 3.3V, ILOAD = 20mA to 40mA 0.19 Line Regulation VLDO = 3.3V to 14V, ILOAD = 20mA VLDO = 3.18V, IDDB = -120mA Dropout Voltage www.maximintegrated.com mA 1.7 mV/mA 0.12 1.8 mV/V 100 180 mV Maxim Integrated │ 2 MAX14856/MAX14858 5kVRMS Isolated 500kbps/25Mbps Full-Duplex RS-485/RS-422 Transceivers with ±35kV ESD Protection DC Electrical Characteristics (continued) (VDDA – VGNDA = 1.71V to 5.5V, VDDB – VGNDB = 3.0V to 5.5V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VDDA – VGNDA = 3.3V, VDDB – VGNDB = 3.3V, VGNDA = VGNDB, and TA = +25°C.) (Notes 2, 3) PARAMETER SYMBOL CONDITIONS Load Capacitance Nominal value (Note 7) Input High Voltage VIH RE, TXD, DE to GNDA VIL RE, TXD, DE to GNDA LOGIC INTERFACE (TXD, RXD, DE, RE, SBA) Input Low Voltage Input Hysteresis 2.25V ≤ VDDA ≤ 5.5V 1.71V ≤ VDDA ≤ 1.89V MIN TYP 1 MAX UNITS 10 µF 0.7 x VDDA 0.78 x VDDA V 2.25V ≤ VDDA ≤ 5.5V 1.71V ≤ VDDA ≤ 1.89V 0.8 V 0.6 VHYS RE, TXD, DE to GNDA 220 mV Input Capacitance CIN RE, TXD, DE, f = 1MHz 2 pF Input Pullup Current IPU TXD -10 -4.5 -1.5 1.5 4.5 10 µA 3 5 8 kΩ Input Pulldown Current IPD RSBA DE, RE SBA Pullup Resistance Output Voltage High VOH RXD to GNDA, IOUT = -4mA Output Voltage Low VOL Short-Circuit Output Pullup Current Short-Circuit Output Pulldown Current Three-State Output Current ISH_PU ISH_PD IOZ VDDA -0.4 V RXD to GNDA, IOUT = 4mA 0.40 SBA to GNDA, IOUT = 4mA 0.45 0V ≤ VRXD ≤ VDDA, (VA - VB) > -10mV, RE = low µA -42 V mA 0V ≤ VRXD ≤ VDDA, (VA - VB) < -200mV, RE = low 40 0V ≤ VSBA ≤ VDDA, side B is powered and working 60 mA 0V ≤ VRXD ≤ VDDA, RE = high -1 RL = 54Ω, TXD = high or low, Figure 1a 1.5 RL = 100Ω, TXD = high or low, Figure 1a 2.0 -7V ≤ VCM ≤ +12V, Figure 1b 1.5 +1 µA DRIVER Differential Driver Output Change in Magnitude of Differential Driver Output Voltage Driver Common Mode Output Voltage Change in Magnitude of Common-Mode Voltage www.maximintegrated.com |VOD| ΔVOD RL = 100Ω or 54Ω, Figure 1a (Note 5) VOC RL = 100Ω or 54Ω, Figure 1a (Note 5) ΔVOC RL = 100Ω or 54Ω, Figure 1a (Note 5) V 5 VDDB/ 2 0.2 V 3 V 0.2 V Maxim Integrated │ 3 MAX14856/MAX14858 5kVRMS Isolated 500kbps/25Mbps Full-Duplex RS-485/RS-422 Transceivers with ±35kV ESD Protection DC Electrical Characteristics (continued) (VDDA – VGNDA = 1.71V to 5.5V, VDDB – VGNDB = 3.0V to 5.5V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VDDA – VGNDA = 3.3V, VDDB – VGNDB = 3.3V, VGNDA = VGNDB, and TA = +25°C.) (Notes 2, 3) PARAMETER SYMBOL CONDITIONS MIN GNDB ≤ VOUT ≤ +12V, output low (Note 6) +30 +250 -7V ≤ VOUT ≤ VDDB, output high (Note 6) -250 -30 Driver Short-Circuit Output Current IOSD Single-Ended Driver Output Voltage High VOH Y and Z outputs, IY,Z = -20mA Single-Ended Driver Output Voltage Low VOL Y and Z outputs, IY,Z = +20mA Differential Driver Output Capacitance COD DE = RE = high, f = 4MHz Input Current (A and B) IA, IB DE = low, VDDB = GNDB or 3.6V Receiver Differential Threshold Voltage VTH -7V ≤ VCM ≤ +12V TYP MAX 2.2 UNITS mA V 0.8 12 V pF RECEIVER Receiver Input Hysteresis ΔVTH Receiver Input Resistance RIN Differential Input Capacitance CA,B VIN = +12V VIN = -7V +250 -200 -200 VCM = 0V -7V ≤ VCM ≤ +12V, DE = low Measured between A and B, DE = RE = low at 6MHz -120 20 48 -10 µA mV mV kΩ 12 pF +160 °C 15 °C PROTECTION Thermal-Shutdown Threshold TSHDN Thermal-Shutdown Hysteresis THYST Temperature Rising ESD Protection (A and B Pins to GNDB) Human Body Model ±35 IEC 61000-4-2 Air Gap Discharge ±18 IEC 61000-4-2 Contact Discharge ±8 ESD Protection (All Other Pins) Human Body Model ±4 www.maximintegrated.com kV kV Maxim Integrated │ 4 MAX14856/MAX14858 5kVRMS Isolated 500kbps/25Mbps Full-Duplex RS-485/RS-422 Transceivers with ±35kV ESD Protection Switching Electrical Characteristics (MAX14856) (VDDA – VGNDA = 1.71V to 5.5V, VDDB – VGNDB = 3.0V to 5.5V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VDDA – VGNDA = 3.3V, VDDB – VGNDB = 3.3V, VGNDA = VGNDB, and TA = +25°C.) (Notes 2, 3) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS DYNAMIC Common Mode Transient Immunity CMTI Glitch Rejection (Note 8) TXD, DE, RXD 35 10 17 kV/μs 29 ns DRIVER tDPLH, tDPHL RL = 54Ω, CL = 50pF, Figure 2 and Figure 3 1040 ns Differential Driver Output Skew |tDPLH - tDPHL| tDSKEW RL = 54Ω, CL = 50pF, Figure 2 and Figure 3 144 ns Driver Differential Output Rise or Fall Time tLH, tHL RL = 54Ω, CL = 50pF, Figure 2 and Figure 3 900 ns Maximum Data Rate DRMAX Driver Propagation Delay 500 kbps Driver Enable to Output High tDZH RL = 110Ω, CL = 50pF, Figure 5 2540 ns Driver Enable to Output Low tDZL RL = 110Ω, CL = 50pF, Figure 5 2540 ns Driver Disable Time from Low tDLZ tDHZ RL = 110Ω, CL = 50pF, Figure 5 140 ns RL = 110Ω, CL = 50pF, Figure 4 140 ns tRPLH, tRPHL CL = 15pF, Figure 6 and Figure 7 (Note 9) 240 ns Receiver Output Skew |tRPLH - tRPHL| tRSKEW CL = 15pF, Figure 6 and Figure 7 (Note 9) 34 ns Maximum Data Rate DRMAX Driver Disable Time from High RECEIVER Receiver Propagation Delay Receiver Enable to Output High 500 kbps Receiver Enable to Output Low tRZL RL = 1kΩ, CL = 15pF, S2 closed, Figure 8 RL = 1kΩ, CL = 15pF, S1 closed, Figure 8 Receiver Disable Time From Low tRLZ RL = 1kΩ, CL = 15pF, S1 closed, Figure 8 20 ns Receiver Disable Time From High tRHZ RL = 1kΩ, CL = 15pF, S2 closed, Figure 8 20 ns www.maximintegrated.com tRZH 20 ns 30 ns Maxim Integrated │ 5 MAX14856/MAX14858 5kVRMS Isolated 500kbps/25Mbps Full-Duplex RS-485/RS-422 Transceivers with ±35kV ESD Protection Switching Electrical Characteristics (MAX14858) (VDDA – VGNDA = 1.71V to 5.5V, VDDB – VGNDB = 3.0V to 5.5V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VDDA – VGNDA = 3.3V, VDDB – VGNDB = 3.3V, VGNDA = VGNDB, and TA = +25°C.) (Notes 2, 3) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS DYNAMIC Common Mode Transient Immunity CMTI Glitch Rejection (Note 8) TXD, DE, RXD 35 10 17 kV/μs 29 ns DRIVER tDPLH, tDPHL RL = 54Ω, CL = 50pF, Figure 2 and Figure 3 65 ns Differential Driver Output Skew |tDPLH - tDPHL| tDSKEW RL = 54Ω, CL = 50pF, Figure 2 and Figure 3 7 ns Driver Differential Output Rise or Fall Time tLH, tHL RL = 54Ω, CL = 50pF, Figure 2 and Figure 3 10 ns Maximum Data Rate DRMAX Driver Propagation Delay 25 Mbps Driver Enable to Output High tDZH RL = 110Ω, CL = 50pF, Figure 4 80 ns Driver Enable to Output Low tDZL RL = 110Ω, CL = 50pF, Figure 5 80 ns Driver Disable Time from Low tDLZ tDHZ RL = 110Ω, CL = 50pF, Figure 5 80 ns RL = 110Ω, CL = 50pF, Figure 4 80 ns tRPLH, tRPHL CL = 15pF, Figure 6 and Figure 7 (Note 9) 65 ns Receiver Output Skew |tRPLH - tRPHL| tRSKEW CL = 15pF, Figure 6 and Figure 7 (Note 9) 7 ns Maximum Data Rate DRMAX Driver Disable Time from High RECEIVER Receiver Propagation Delay 25 Receiver Enable to Output High tRZH Receiver Enable to Output Low tRZL RL = 1kΩ, CL = 15pF, S2 closed, Figure 8 RL = 1kΩ, CL = 15pF, S1 closed, Figure 8 Receiver Disable Time From Low tRLZ Receiver Disable Time From High tRHZ Mbps 20 ns 30 ns RL = 1kΩ, CL = 15pF, S1 closed, Figure 8 20 ns RL = 1kΩ, CL = 15pF, S2 closed, Figure 8 20 ns Note 2: All devices are 100% production tested at TA = +25°C. Specifications over temperature are guaranteed by design. Note 3: All currents into the device are positive. All currents out of the device are negative. All voltages are referenced to their respective ground (GNDA or GNDB), unless otherwise noted. Note 4: VLDO max indicates voltage capability of the circuit. Power dissipation requirements may limit VLDO max to a lower value. Note 5: ΔVOD and ΔVOC are the changes in VOD and VOC, respectively, when the TXD input changes state. Note 6: The short circuit output current applies to the peak current just prior to current limiting. Note 7: Not production tested. Guaranteed by design. Note 8: CMTI is the maximum sustainable common-mode voltage slew rate while maintaining the correct output states. CMTI applies to both rising and falling common-mode voltage edges. Tested with the transient generator connected between GNDA and GNDB. VCM = 1kV Note 9: Capacitive load includes test probe and fixture capacitance. www.maximintegrated.com Maxim Integrated │ 6 MAX14856/MAX14858 5kVRMS Isolated 500kbps/25Mbps Full-Duplex RS-485/RS-422 Transceivers with ±35kV ESD Protection Insulation Characteristics PARAMETER Partial Discharge Test Voltage SYMBOL VPR CONDITIONS VALUE UNITS Method B1 = VIORM x 1.875 (t = 1s, partial discharge < 5pC) 2250 VP Maximum Repetitive Peak Withstand Voltage VIORM (Note 7) 1200 VP Maximum Working Isolation Voltage VIOWM (Note 7) 848 VRMS Maximum Transient Isolation Voltage VIOTM t = 1s 8400 VP Maximum Withstand Isolation Voltage VISO t = 60s, f = 60Hz (Note 7, 8) 5000 VRMS 10 kV >109 Ω Maximum surge Isolation Voltage Insulation Resistance VIOSM RS IEC 61000-4-5, 1.2/50μs TA = +150°C, VIO = 500V Barrier Capacitance Input to Output CIO 2 pF Creepage Distance CPG Wide SO 8 mm Clearance Distance CLR Wide SO 8 mm 0.015 mm Internal Clearance Comparitive Tracking Resistance Index Distance through insulation CTI Material Group II (IEC 60112) Climatic Category 575 40/125/21 Pollution Degree (DIN VDE 0110, Table 1) 2 Note 10: VIORM, VIOWM, and VISO are defined by the IEC 60747-5-5 standard. Note 11: Product is qualified at VISO for 60 seconds. 100% production tested at 120% of VISO for 1 second. Safety Regulatory Approvals (Pending) UL The MAX14856/MAX14858 is certified under UL1577. For more details, see File E351759. Rate up to 5000VRMS isolation voltage for basic insulation. cUL Pending VDE Pending TUV Pending www.maximintegrated.com Maxim Integrated │ 7 MAX14856/MAX14858 5kVRMS Isolated 500kbps/25Mbps Full-Duplex RS-485/RS-422 Transceivers with ±35kV ESD Protection 375Ω Y Y RL 2 VOD VOD 60Ω + - VOC RL 2 Z Z VCM 375Ω (b) (a) Figure 1. Driver DC Test Load TXD Y Z VOD RL CL GNDA Figure 2. Driver Timing Test Circuit tLH P 3ns, tHL P 3ns VDDA 50% TXD 50% GNDA 1/2 VO tDPHL tDPLH Z Y 1/2 VO VO VDIFF = VY - VZ VO 80% 80% VDIFF 0 20% 20% tLH -VO tHL tDSKEW = |tDPLH - tDPHL| Figure 3. Driver Propagation Delays www.maximintegrated.com Maxim Integrated │ 8 MAX14856/MAX14858 Y GNDA OR VDDA TXD D Z DE 5kVRMS Isolated 500kbps/25Mbps Full-Duplex RS-485/RS-422 Transceivers with ±35kV ESD Protection S1 VDDA OUT CL 50pF DE RL = 500I 50% 250mV OUT GENERATOR 50% GNDB 50I GNDA tDZH tDHZ VOH GNDB GNDA Figure 4. Driver Enable and Disable Times (tDHZ, tDZH) VDDB GNDA OR VDDA TXD D Y Z DE GENERATOR RL = 500I S1 OUT CL = 50pF GNDB 50I GNDA VDDA DE 50% GNDA tDZL tDLZ VDDB 50% OUT 250mV VOL Figure 5. Driver Enable and Disable Times (tDZL, tDLZ) A ATE R VID RECEIVER OUTPUT B Figure 6. Receiver Propagation Delay Test Circuit www.maximintegrated.com Maxim Integrated │ 9 MAX14856/MAX14858 5kVRMS Isolated 500kbps/25Mbps Full-Duplex RS-485/RS-422 Transceivers with ±35kV ESD Protection tLH P 3ns, tHL P 3ns A 1V B -1V tRPHL tRPLH VDDA 2 RXD VOH VDDA 2 VOL tRSKEW = |tRPHL - tRPLH| Figure 7. Receiver Propagation Delays +1.5V S3 -1.5V VID GNDB GENERATOR R RE RXD RL 1kI S1 VDDA S2 CL 15pF GNDA 50I GNDA VDDA VDDA 50% RE S1 OPEN S2 CLOSED GNDA S3 = +1.5V 50% RE GNDA tRZL tRZH VOH VDDA 2 GNDA RXD VDDA 50% RE VDDA 2 RXD S1 OPEN S2 CLOSED S3 = +1.5V VDDA RE 50% GNDA GNDA RXD VDDA VOL S1 CLOSED S2 OPEN S3 = -1.5V tRLZ tRHZ 0.25V S1 CLOSED S2 OPEN S3 = -1.5V VDDA VOH RXD GNDA 0.25V VOL Figure 8. Receiver Enable and Disable Times www.maximintegrated.com Maxim Integrated │ 10 MAX14856/MAX14858 5kVRMS Isolated 500kbps/25Mbps Full-Duplex RS-485/RS-422 Transceivers with ±35kV ESD Protection Typical Operating Characteristics (VDDA – VGNDA = 3.3V, VDDB – VGNDB = 3.3V, VGNDA = VGNDB, and TA = +25°C, unless otherwise noted.) VDDA SUPPLY CURRENT vs. TEMPERATURE 8 toc01 14 7 3.5 8 6 3 NO LOAD NO SWITCHING -45 -30 -15 0 15 30 45 60 75 0 90 105 NO LOAD NO SWITCHING -45 -30 -15 TEMPERATURE (°C) 240 220 0 15 30 45 700 tPDHL 500 400 tPDLH 200 -45 -30 -15 0 15 30 45 60 75 0.0 90 105 60 75 1000 CL = 15pF -45 -30 -15 180 160 140 120 100 tRPLH 80 60 90 105 0 -45 -30 -15 0 15 30 45 60 75 45 60 75 90 105 800 700 600 tDZH tDZL 500 400 300 200 0 90 105 tDHZ tDLZ -45 -30 -15 toc08 VOUTN RXD 2V/div VINSIDE 0V 0V VBACKUP Y 1V/div B 1V/div Z 1V/div A 1V/div PROPAGATION DELAY (ns) CL = 15pF 100ns/div 0 15 30 45 60 75 90 105 TEMPERATURE (°C) TXD 2V/div RL = 54Ω CL = 50pF 30 100 MAX14856 RECEIVER PROPAGATION DELAY toc07 15 MAX14856 DRIVER ENABLE/DISABLE DELAY vs. TEMPERATURE toc06 TEMPERATURE (°C) MAX14856 DRIVER PROPAGATION DELAY 0 900 tRPHL 20 TEMPERATURE (°C) 100ns/div 54Ω LOAD TEMPERATURE (°C) 40 RL = 54Ω CL = 50pF 100 120Ω LOAD 0.5 MAX14856 RECEIVER PROPAGATION DELAY vs. TEMPERATURE toc05 200 800 PROPAGATION DELAY (ns) PROPAGATION DELAY (ns) 900 300 2.0 TEMPERATURE (°C) MAX14856 TRANSMITTER PROPAGATION DELAY vs. TEMPERATURE toc04 600 2.5 1.0 2 ENABLE/DISABLE DELAY (ns) 1 toc03 No load 1.5 4 2 DIFFERENTIAL OUTPUT VOLTAGE vs. TEMPERATURE 3.0 VOD (V) IDDB (mA) IDDA (mA) 4 0 4.0 10 5 1000 toc02 12 6 0 VDDB SUPPLY CURRENT vs. TEMPERATURE 65 60 55 50 45 40 35 30 25 20 15 10 5 0 MAX14858 TRANSMITTER PROPAGATION DELAY vs. TEMPERATURE toc09 tPDHL tPDLH RL = 54Ω CL = 50pF -45 -30 -15 0 15 30 45 60 75 90 105 TEMPERATURE (°C) www.maximintegrated.com Maxim Integrated │ 11 MAX14856/MAX14858 5kVRMS Isolated 500kbps/25Mbps Full-Duplex RS-485/RS-422 Transceivers with ±35kV ESD Protection Typical Operating Characteristics (continued) 80 tRPLH 0 15 30 45 60 75 tDZH tDHZ 60 TXD 2V/div VOUTN 50 0V VINSIDE 40 30 tDLZ Y 1V/div VBACKUP tDZL 20 Z 1V/div 10 CL = 15pF -45 -30 -15 toc12 RL = 54Ω CL = 50pF 70 tRPHL MAX14858 DRIVER PROPAGATION DELAY MAX14858 DRIVER ENABLE/DISABLE DELAY vs. TEMPERATURE toc11 0 90 105 -45 -30 -15 TEMPERATURE (°C) 0 15 30 45 60 75 10ns/div 90 105 TEMPERATURE (°C) toc13 A 1V/div VOUTN B 1V/div VINSIDE VBACKUP RECEIVER ENABLE/DISABLE DELAY vs. TEMPERATURE 20 RXD 2V/div 0V toc14 6 14 tRZL 12 tRZH tRHZ 10 5 tRLZ 8 6 10ns/div 4 3 2 4 0 toc15 7 16 1 2 CL = 15pF VDDA SUPPLY CURRENT vs. DATA RATE 8 18 ENABLE/DISABLE DELAY (ns) MAX14858 RECEIVER PROPAGATION DELAY IDDA (mA) 65 60 55 50 45 40 35 30 25 20 15 10 5 0 MAX14858 RECEIVER PROPAGATION DELAY vs. TEMPERATURE toc10 ENABLE/DISABLE DELAY (ns) PROPAGATION DELAY (ns) (VDDA – VGNDA = 3.3V, VDDB – VGNDB = 3.3V, VGNDA = VGNDB, and TA = +25°C, unless otherwise noted.) -45 -30 -15 0 15 30 45 60 75 90 105 TEMPERATURE (°C) 0 5 10 15 20 25 DATA RATE (Mbps) VDDB SUPPLY CURRENT vs. DATA RATE 70 0 toc16 54Ω LOAD 60 IDDB (mA) 50 40 30 120Ω LOAD 20 10 0 NO LOAD 0 5 10 15 20 25 DATA RATE (Mbps) www.maximintegrated.com Maxim Integrated │ 12 MAX14856/MAX14858 5kVRMS Isolated 500kbps/25Mbps Full-Duplex RS-485/RS-422 Transceivers with ±35kV ESD Protection Pin Configuration TOP VIEW + VDDA 1 GNDA 2 RXD 3 RE 4 13 B DE 5 12 Z TXD 6 11 Y SBA 7 10 VLDO GNDA 8 9 16 VDDB MAX14856 MAX14858 15 GNDB 14 A GNDB WIDE SOIC Pin Description PIN NAME REFERENCE 1 VDDA GNDA 2, 8 GNDA - 3 RXD GNDA Receiver Data Output. Drive RE low to enable RXD. With RE low, RXD is high when (VA – VB) > -10mV and is low when (VA – VB) < -200mV. RXD is high when VDDB is less than VUVLOB. RXD is high impedance when RE is high. 4 RE GNDA Receiver Output Enable. Driver RE low or connect to GNDA to enable RXD. Drive RE high to disable RXD. RXD is high-impedance when RE is high. RE has an internal 4.5µA pulldown to GNDA. 5 DE GNDA Driver Output Enable. Drive DE high to enable bus driver outputs Y and Z. Drive DE low or connect to GNDA to disable Y and Z. Y and Z are high impedance when DE is low. DE has an internal 4.5µA pull-down to GNDA. 6 TXD GNDA Driver Input. With DE high, a low on TXD forces the noninverting output (Y) low and the inverting output (Z) high. Similarly, a high on TXD forces the noninverting output high and the inverting output low. TXD has an internal 4.5µA pullup to VDDA. 7 SBA GNDA Side B Active Indicator Output. SBA asserts low when side B is powered and working. SBA has an internal 5kΩ pull-up resistor to VDDA. www.maximintegrated.com FUNCTION UART/Logic-Side Power Input. Bypass VDDA to GNDA with both 0.1µF and 1µF capacitors as close to the device as possible. UART/Logic-Side Ground. GNDA is the ground reference for digital signals. Maxim Integrated │ 13 MAX14856/MAX14858 5kVRMS Isolated 500kbps/25Mbps Full-Duplex RS-485/RS-422 Transceivers with ±35kV ESD Protection Pin Description (continued) PIN NAME REFERENCE 9, 15 GNDB - FUNCTION Cable Side Ground. GNDB is the ground reference for the internal LDO and the RS-485/ RS-422 bus signals. 10 VLDO GNDB LDO Power Input. Connect a minimum voltage of 3.18V to VLDO to power the cable side of the transceiver. Bypass VLDO to GNDB with both 0.1µF and 1µF capacitors as close to the device as possible. To disable the internal LDO, leave VLDO unconnected or connect to GNDB. 11 Y GNDB Noninverting Driver Output 12 Z GNDB Inverting Driver Output 13 B GNDB Inverting Receiver Input 14 A GNDB Noninverting Receiver Input GNDB Cable Side Power Input/Isolated LDO Power Output. Bypass VDDB to GNDB with both 0.1µF and 1μF capacitor as close to the device as possible. VDDB is the output of the internal LDO when power is applied to VLDO. When the internal LDO is not used (VLDO is unconnected or connected to GNDB), VDDB is the positive supply input for the cable side of the IC. 16 VDDB www.maximintegrated.com Maxim Integrated │ 14 MAX14856/MAX14858 5kVRMS Isolated 500kbps/25Mbps Full-Duplex RS-485/RS-422 Transceivers with ±35kV ESD Protection Function Tables Transmitting INPUTS OUTPUTS VDDA VDDB DE TXD Y Z ≥ VUVLOA ≥ VUVLOB 1 1 1 0 ≥ VUVLOA ≥ VUVLOB 1 0 0 1 ≥ VUVLOA ≥ VUVLOB 0 X High-Z High-Z < VUVLOA ≥ VUVLOB X X High-Z High-Z ≥ VUVLOA < VUVLOB X X High-Z High-Z < VUVLOA < VUVLOB X X High-Z High-Z *Note: Drive DE low to disable the transmitter outputs. Drive DE high to enable the transmitter outputs. DE has an internal pulldown to GNDA. X = Don’t care RECEIVING INPUTS OUTPUTS VDDA VDDB RE (VA- VB) RXD ≥ VUVLOA ≥ VUVLOB 0 > -10mV 1 ≥ VUVLOA ≥ VUVLOB 0 < -200mV 0 ≥ VUVLOA ≥ VUVLOB 0 Open/Short 1 ≥ VUVLOA ≥ VUVLOB 1 X High-Z < VUVLOA ≥ VUVLOB X X High-Z ≥ VUVLOA < VUVLOB 0 X 1 < VUVLOA < VUVLOB X X High-Z *Note: Drive RE high to disable the receiver output. Drive RE low to enable to receiver output. RE has an internal pulldown to GNDA. X = Don’t care SBA VDDA VDDB SBA < VUVLOA < VUVLOB High < VUVLOA ≥ VUVLOB High ≥ VUVLOA < VUVLOB High ≥ VUVLOA ≥ VUVLOB Low www.maximintegrated.com Maxim Integrated │ 15 MAX14856/MAX14858 5kVRMS Isolated 500kbps/25Mbps Full-Duplex RS-485/RS-422 Transceivers with ±35kV ESD Protection Detailed Description The MAX14856/MAX14858 isolated RS-485/RS-422 transceivers provide 5000VRMS (60s) of galvanic isolation between the RS-485/RS-422 cable side of the transceiver and the UART side. These devices allow up to 500kbps (MAX14856)/25Mbps (MAX14858) communication across an isolation barrier when a large potential exists between grounds on each side of the barrier. Isolation Data isolation is achieved using high-voltage capacitors that allow data transmission between the UART side and the RS-485/RS-422 cable side of the transceiver. Integrated LDO The devices include an internal low-dropout regulator with a set 3.3V (typ) output that is used to power the cableside of the IC. The output of the LDO is VDDB. The LDO has a 300mA (typ) current limit. If the LDO is unused, connect VLDO to GNDB and apply +3.3V directly to VDDB. True Fail-Safe The devices guarantee a logic-high on the 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 (VA – VB) is greater than or equal to -10mV, RXD is logichigh. In the case of a terminated bus with all transmitters disabled, the receiver’s differential input voltage is pulled to zero by the termination resistors. Due to the receiver thresholds of the devices, this results in a logic-high at RXD. www.maximintegrated.com Driver Output Protection Two mechanisms prevent excessive output current and power dissipation caused by faults or bus contention. The first, a current limit on the output stage, provides immediate protection against short circuits over the entire common-mode voltage range. The second, a thermalshutdown circuit, forces the driver outputs into a high-impedance state if the die temperature exceeds +160°C (typ). Thermal Shutdown The devices are protected from overtemperature damage by integrated thermal shutdown circuitry. When the junction temperature (TJ) exceeds +160°C (typ), the driver outputs go high-impedance. The device resumes normal operation when TJ falls below +145°C (typ). Applications Information 128 Transceivers on the Bus The standard RS-485 receiver input impedance is one unit load. A standard driver can drive up to 32 unit-loads. The devices’ transceivers have a 1/4-unit load receiver, which allows up to 128 transceivers, connected in parallel, on one communication line. Connect any combination of these devices, and/or other RS-485 devices, for a maximum of 32 unit-loads to the line. Typical Application The MAX14856/MAX14858 full-duplex transceivers are designed for bidirectional data communications on multipoint bus transmission lines. Figure 9 and Figure 10 show typical network application circuits. To minimize reflections, the bus should be terminated at both ends in its characteristics impedance, and stub lengths off the main line should be kept as short as possible. Maxim Integrated │ 16 MAX14856/MAX14858 5kVRMS Isolated 500kbps/25Mbps Full-Duplex RS-485/RS-422 Transceivers with ±35kV ESD Protection Slave RXD RE TXD DE Y RS-485 TRANSCEIVER RS-485 TRANSCEIVER Master A 120Ω Z B B A B RS-485 TRANSCEIVER RXD RE TXD DE A RS-485 TRANSCEIVER MAX14856 MAX14858 INTEGRATED ISOLATION BARRIER Slave Slave DE TXD RE RXD DE TXD RE RXD Figure 9. Typical Isolated Full-Duplex RS-485/RS-422 Application VLDO VLDO 0.1uF 1uF 0.1uF 1 2 VDDB 1uF 0.1uF LDO RXD RE TXD DE Y 0.1uF 2 Z 1uF 3 120Ω A B 1 2 VDDB 3 A B Y 120Ω 2 LDO 0.1uF 3 VDDA MAX14856 MAX14858 RS-485 TRANSCEIVER 1 1uF 2 MAX14856 MAX14858 RS-485 TRANSCEIVER VDDA 1uF 3 1uF 0.1uF RXD 4 4 RE TXD DE Z 3 4 Figure 10. Typical Isolated Point-to-Point Application www.maximintegrated.com Maxim Integrated │ 17 MAX14856/MAX14858 5kVRMS Isolated 500kbps/25Mbps Full-Duplex RS-485/RS-422 Transceivers with ±35kV ESD Protection Layout Considerations It is recommended to design an isolation, or “keep-out,” channel underneath the isolator that is free from ground and signal planes. Any galvanic or metallic connection between the cable side and UART side will defeat the isolation. Ensure that the decoupling capacitors between VDDA and GNDA and between VLDO, VDDB, and GNDB are located as close as possible to the IC to minimize inductance. Route important signal lines close to the ground plane to minimize possible external influences. On the cable side of the devices, it is good practice to have the bus connectors and termination resistor as close as possible to the A and B pins. Extended ESD Protection ESD protection structures are incorporated on all pins to protect against electrostatic discharge encountered during handling and assembly. The driver outputs and receiver inputs of the MAX14856/MAX14858 have extra protection against static electricity to both the UART side and cable side ground references. The ESD structures withstand high-ESD events during normal operation and when powered down. After an ESD event, the devices keep working without latch-up or damage. Bypass VDDA to GNDA and bypass VDDB and VLDO to GNDB with 0.1μF and 1μF capacitors to ensure maximum ESD protection. ESD protection can be tested in various ways. The transmitter outputs and receiver inputs of the MAX14856/ MAX14858 are characterized for protection to the cable side ground (GNDB) to the following limits: ●● ±35kV HBM ●● ±18kV using the Air-Gap Discharge method specified in IEC 61000-4-2 ●● ±8kV using the Contact Discharge method specified in IEC 61000-4-2 www.maximintegrated.com ESD Test Conditions ESD performance depends on a variety of conditions. Contact Maxim for a reliability report that documents test setup, test methodology, and test results. Human Body Model (HBM) Figure 11 shows the HBM test model, while Figure 12 shows the current waveform it generates when discharged in a low-impedance state. 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. IEC 61000-4-2 The IEC 61000-4-2 standard covers ESD testing and performance of finished equipment. However, it does not specifically refer to integrated circuits. The MAX14856/ MAX14858 help in designing equipment to meet IEC 61000-4-2 without the need for additional ESD protection components. The major difference between tests done using the HBM and IEC 61000-4-2 is higher peak current in IEC 61000-4-2 because series resistance is lower in the IEC 61000-4-2 model. Hence, the ESD withstand voltage measured to IEC 61000-4-2 is generally lower than that measured using the HBM. Figure 13 shows the IEC 61000-4-2 model and Figure 14 shows the current waveform for IEC 61000-4-2 ESD Contact Discharge Test. Maxim Integrated │ 18 MAX14856/MAX14858 RC 1MΩ CHARGE-CURRENTLIMIT RESISTOR HIGHVOLTAGE DC SOURCE Cs 100pF 5kVRMS Isolated 500kbps/25Mbps Full-Duplex RS-485/RS-422 Transceivers with ±35kV ESD Protection RD 1500Ω IP 100% 90% DISCHARGE RESISTANCE STORAGE CAPACITOR Ir AMPS DEVICE UNDER TEST 36.8% 10% 0 0 Figure 11. Human Body ESD Test Model CHARGE-CURRENTLIMIT RESISTOR HIGHVOLTAGE DC SOURCE Cs 150pF TIME tDL CURRENT WAVEFORM Figure 12. Human Body Current Waveform RD 330Ω I 100% 90% DISCHARGE RESISTANCE STORAGE CAPACITOR tRL IPEAK RC 50MΩ TO 100MΩ PEAK-TO-PEAK RINGING (NOT DRAWN TO SCALE) DEVICE UNDER TEST 10% tr = 0.7ns TO 1ns t 30ns 60ns Figure 13. IEC 61000-4-2 ESD Test Model www.maximintegrated.com Figure 14. IEC 61000-4-2 ESD Generator Current Waveform Maxim Integrated │ 19 MAX14856/MAX14858 5kVRMS Isolated 500kbps/25Mbps Full-Duplex RS-485/RS-422 Transceivers with ±35kV ESD Protection Typical Application Circuit VLDO VDDA MAX14856 MAX14858 VDDB LDO SBA A RS-485 TRANSCEIVER RXD RE uC TXD DE GNDA B Y Z GNDB ISOLATION BARRIER www.maximintegrated.com Maxim Integrated │ 20 MAX14856/MAX14858 5kVRMS Isolated 500kbps/25Mbps Full-Duplex RS-485/RS-422 Transceivers with ±35kV ESD Protection Ordering Information PART Package Information TEMP RANGE PIN-PACKAGE MAX14856GWE+ -40°C to +105°C 16 SOIC (W) MAX14856GWE+T -40°C to +105°C 16 SOIC (W) MAX14858GWE+ -40°C to +105°C 16 SOIC (W) MAX14858GWE+T -40°C to +105°C 16 SOIC (W) +Denotes a lead(Pb)-free/RoHS-compliant package. T = Tape and Reel. For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. PACKAGE TYPE PACKAGE CODE OUTLINE NO. LAND PATTERN NO. 16 SOIC W16M+9 21-0042 90-0107 Chip Information PROCESS: BiCMOS www.maximintegrated.com Maxim Integrated │ 21 MAX14856/MAX14858 5kVRMS Isolated 500kbps/25Mbps Full-Duplex RS-485/RS-422 Transceivers with ±35kV ESD Protection Revision History REVISION NUMBER REVISION DATE 0 11/15 DESCRIPTION Initial release PAGES CHANGED — For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com. 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. © 2015 Maxim Integrated Products, Inc. │ 22