XR3178EID-F

XR3170E-3178E 3.3V HIGH SPEED RS-485/RS-422 TRANSCEIVERS WITH 1/8th UNIT LOAD DECEMBER 2009 REV. 1.0.0 GENERAL DESCRIPTION FEATURES The XR3170E - XR3178E family of RS-485 devices are designed for reliable, bidirectional communication on multipoint bus transmission lines. Each device contains one differential driver and one differential receiver. XR3172E, XR3175E and XR3178E are halfduplex devices; other part numbers are full-duplex. All devices comply with TIA/EIA-485 and TIA/EIA-422 standards. Lead free and RoHS compliant packages are available for all models. • 3.3V Single Supply Operation • High Speed 20Mbps Data Rate • Slew Rate Limited - 250kbps And 500kbps Data These devices are ruggedized for use in harsh operating conditions over the entire common-mode voltage range from -7V to +12V. Receivers are specially designed to fail-safe to a logic high output state if the inputs are left un-driven or shorted. All RS485 bus pins are protected against severe ESD events up to +/-15kV (Air-Gap and Human Body Model) and up to +/-8kV Contact Discharge (IEC 61000-4-2). Drivers are protected from excess current flow caused by bus contention or output short-circuits by both an internal current limit and a thermal-overload shutdown. Devices are rated for Industrial (-40 to +85°C) operating temperatures. Receivers have exceptionally high input impedance, which places only 1/8th the standard load on a shared bus. Up to 256 transceivers may coexist while preserving full signal margin. • Robust ESD Protection For RS-485 Pins All devices operate from a single 3.3V power supply and draw negligible quiescent power. All versions except the XR3171E, XR3174E and XR3177E may independently enable and disable their driver and receiver and enter a low power shutdown mode if both driver and receiver are disabled. All outputs maintain high impedance in shutdown or when powered off. • Building Automation • Security Systems • Remote Utility Meter Reading • Long Or Un-Terminated Transmission Lines Rate • 1/8th Unit Load, 256 Transceivers On Bus • Enhanced Failsafe For Receiver - Open, Short Or Terminated Lines ■ +/-15kV Air-Gap Discharge ■ +/-15kV Human Body Model ■ +/-8kV Contact Discharge • Hot Swap Glitch Protection • Driver Short Circuit Current Limit And Thermal Shutdown For Overload Protection • Ultra-Low 650uA Quiescent Current • 1µA Shutdown Mode • Industry Standard Package Footprints TYPICAL APPLICATIONS • Motor Control FIGURE 1. TYPICAL APPLICATION CIRCUIT DE DE XR3178E XR3178E B DI B STUB RT DI RT A A RO RO B RE A XR3178E A XR3178E B DE RE RE DE DI RO RE DI RO Exar Corporation 48720 Kato Road, Fremont CA, 94538 • (510) 668-7000 • FAX (510) 668-7017 • www.exar.com XR3170E-3178E 3.3V HIGH SPEED RS-485/RS-422 TRANSCEIVERS WITH 1/8th UNIT LOAD REV. 1.0.0 FIGURE 2. PIN OUT ASSIGNMENT 8 VCC RO 1 RE 2 DE 3 DI 4 VCC 1 RO 2 DI 3 GND 4 NC 1 14 VCC RO 2 13 NC RE 3 DE 4 DI 5 GND 6 9 Y GND 7 8 NC 8-Pin NSOIC Half Duplex XR3172E XR3175E XR3178E 8-Pin NSOIC Full Duplex XR3171E XR3174E XR3177E 14-Pin NSOIC Full Duplex XR3170E XR3173E XR3176E 7 B 6 A 5 GND 8 A 7 B 6 Z 5 Y 12 A 11 B 10 Z ORDERING INFORMATION PART NUMBER PACKAGE OPERATING TEMPERATURE RANGE DEVICE STATUS XR3170EID 14-pin Narrow SOIC -40°C to +85°C Active XR3171EID 8-pin Narrow SOIC -40°C to +85°C Active XR3172EID 8-pin Narrow SOIC -40°C to +85°C Active XR3173EID 14-pin Narrow SOIC -40°C to +85°C Active XR3174EID 8-pin Narrow SOIC -40°C to +85°C Active XR3175EID 8-pin Narrow SOIC -40°C to +85°C Active XR3176EID 14-pin Narrow SOIC -40°C to +85°C Active XR3177EID 8-pin Narrow SOIC -40°C to +85°C Active XR3178EID 8-pin Narrow SOIC -40°C to +85°C Active Note: Please visit www.exar.com for tape and reel option part numbers. 2 XR3170E-3178E 3.3V HIGH SPEED RS-485/RS-422 TRANSCEIVERS WITH 1/8th UNIT LOAD REV. 1.0.0 PIN DESCRIPTIONS Pin Assignments PIN NUMBER HALF DUPLEX FULL DUPLEX XR3172E XR3175E XR3178E XR3171E XR3174E XR3177E XR3170E XR3173E XR3176E 1 2 2 2 3 - - 3 4 PIN NAME TYPE DESCRIPTION RO O Receiver Output. When RE is low and if (AB) ≥ -50mV, RO is High. If (A-B) ≤ -200mV, RO is Low. I Receiver Output Enable. When RE is Low, RO is enabled. When RE is High, RO is high impedance. RE should be High and DE should be low to enter shutdown mode. RE is a hot-swap input. I Driver Output Enable. When DE is High, outputs are enabled. When DE is low, outputs are high impedance. DE should be low and RE should be High to enter shutdown mode. DE is a hot-swap input. Driver Input. With DE high, a low level on DI forces Non-Inverting output low and inverting output high. Similarly, a high level on DI forces Non-Inverting output High and Inverting output Low. RE DE 4 3 5 DI I 5 4 6, 7 GND Pwr Ground. 6 - - A I/O Non-Inverting Receiver Input and NonInverting Driver Output. 7 - - B I/O Inverting Receiver Input and Inverting Driver Output. 8 1 14 Vcc Pwr +3.3V power supply input. Bypass with 0.1uF capacitor. - 8 12 A I Non-Inverting Receiver Input. - 7 11 B I Inverting Reciever Input. - 5 9 Y O Non-Inverting Driver Output. - 6 10 Z O Inverting Driver Output. - - 1, 8, 13 NC - No Connect, not internally connected. Pin type: I=Input, O=Output. 3 XR3170E-3178E 3.3V HIGH SPEED RS-485/RS-422 TRANSCEIVERS WITH 1/8th UNIT LOAD REV. 1.0.0 ABSOLUTE MAXIMUM RATINGS These are stress ratings only and functional operation of the device at these ratings or any other above those indicated in the operation sections to the specifications below is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability and cause permanent damage to the device. VCC +6.0V Input Voltage at control pins (RE, DE and DI) -0.3V to (VCC + 0.3V) Driver Output Voltage (A, B, Y and Z) -8V to +13V Receiver Output Voltage (RO) -0.3V to (VCC + 0.3V) Receiver Input Voltage (A and B) -8V to +13V Storage Temperature Range -65°C to + 150°C Lead Temperature (soldering, 10s) +300°C Package Power Dissipation Maximum Junction Temperature 150°C 8-Pin SO θJA = 128.4°C/W 14-Pin SO θJA = 86°C/W CAUTION: ESD (Electrostatic Discharge) sensitive device. Permanent damage may occur on unconnected devices subject to high energy electrostatic fields. Unused devices must be stored in conductive foam or shunts. Personnel should be properly grounded prior to handling this device. The protective foam should be discharged to the destination socket before devices are removed. ELECTRICAL CHARACTERISTICS UNLESS OTHERWISE NOTED: VCC = +3.0V TO +3.6V WITH TA FROM -40OC TO +85OC. TYPICAL VALUES ARE AT VCC = +3.3V AND 25OC. SYMBOL PARAMETERS MIN. TYP. MAX. UNITS Vcc V CONDITIONS DRIVER DC CHARACTERISTICS VOD ∆VOD Differential Driver Output Change in Magnitude of Differential Output No Load 2.0 2.65 RL = 100Ω (RS-422), Figure 3 1.7 2.35 RL = 54Ω (RS-485), Figure 3 1.7 2.35 VCM = -7V, Figure 4 1.7 2.35 VCM = +12V, Figure 4 -0.20 0.20 V RL = 100Ω (RS-422), Figure 3, See Note 1 -0.20 0.20 RL = 54Ω (RS-485), Figure 3, See Note 1 -0.20 0.20 VCM = -7V, Figure 4, See Note 1 -0.20 VOC Driver Common Mode Output Voltage steady state 3.0 4 VCM = +12V, Figure 4, See Note 1 0.20 V Figure 3 XR3170E-3178E 3.3V HIGH SPEED RS-485/RS-422 TRANSCEIVERS WITH 1/8th UNIT LOAD REV. 1.0.0 UNLESS OTHERWISE NOTED: VCC = +3.0V TO +3.6V WITH TA FROM -40OC TO +85OC. TYPICAL VALUES ARE AT VCC = +3.3V AND 25OC. SYMBOL PARAMETERS MIN. TYP. MAX. UNITS ∆VOC Change in Magnitude of Common Mode Output Voltage -0.2 0.2 V IOSD Driver Short Circuit Current Limit -250 250 mA VIH 2.0 Figure 3, See Note 1 -7V ≤ VOUT ≤ 12V, Figure 5 V Logic Input High V Logic Input Low Logic Input Thresholds (DI, DE, RE) VIL VHYS CONDITIONS 0.8 Driver Input Hysteresis 100 IIN Logic Input Current (DI, DE and RE) IOL Output Leakage Current (Full-Duplex versions, Y and Z pins) Note 2 -1 mV TA = 25°C 1 µA 0V ≤ IN ≤ +Vcc, after first transition, Note 2 125 µA Vout = 12V, DE = 0V, RE = 0V, Vcc = 0V or 3.3V. µA Vout = -7V, DE = 0V, RE = 0V, Vcc = 0V or 3.3V. KΩ -7V ≤ VCM ≤ 12V µA DE = 0V, Vcc = 0V or 3.3V, VIN = 12V µA DE = 0V, Vcc = 0V or 3.3V, VIN = -7V mV -7V ≤ VCM ≤ 12V mV VCM = 0V -100 RECEIVER DC CHARACTERISTICS RIN Receiver Input Resistance IIN Input Current (A, B pins) VIH,VIL 96 160 70 Receiver Differential Thresholds (VA - VB) -100 -55 -200 -120 Receiver Input Hysteresis -50 25 VOH Receiver Output Voltage High VOL Receiver Output Voltage Low IOZ High-Z Receiver Output Current IOSC 125 Vcc 0.6 +/0.03 Receiver Output Short Circuit Current V IOUT = -8mA, VID = -50mV 0.4 V IOUT = 8mA, VID = -200mV +/-1.0 µA Vcc = 3.3V, 0.40V ≤ Vout ≤ 2.4V +/-95 mA 0V ≤ VRO ≤ Vcc 950 µA No Load, DE = Vcc, DI = 0V or Vcc 1 µA DE = 0V, RE = Vcc, DI = 0V or Vcc SUPPLY AND PROTECTION ICC1 Supply Current - Driver Enabled 650 ICC2 Supply Current - Shutdown Mode TSD Thermal Shutdown Temperature 165 °C Junction temperature, Note 4 Thermal Shutdown Hysteresis 15 °C Note 4 XR3170E, XR3171E, XR3172E DRIVER AC CHARACTERISTICS freq Max. Data Signaling Rate 250 kbps 5 1/tUI, Duty Cycle 40 to 60% XR3170E-3178E 3.3V HIGH SPEED RS-485/RS-422 TRANSCEIVERS WITH 1/8th UNIT LOAD REV. 1.0.0 UNLESS OTHERWISE NOTED: VCC = +3.0V TO +3.6V WITH TA FROM -40OC TO +85OC. TYPICAL VALUES ARE AT VCC = +3.3V AND 25OC. SYMBOL PARAMETERS MIN. TYP. MAX. UNITS CONDITIONS tPLH Driver Propagation Delay (Low to High) 250 1500 ns CL = 50pF, RL = 54Ω, Figures 6 and 7 tPHL Driver Propagation Delay (High to Low) 250 1500 ns CL = 50pF, RL = 54Ω, Figures 6 and 7 tR Driver Rise Time 350 1600 ns CL = 50pF, RL = 54Ω, Figures 6 and 7 tF Driver Fall Time 350 1600 ns CL = 50pF, RL = 54Ω, Figures 6 and 7 Differential Pulse Skew 200 ns Figures 6 and 7 tZH Driver Enable to Output High 2500 ns CL = 50pF, RL = 500Ω, Figures 8 and 9 tZL Driver Enable to Output Low 2500 ns CL = 50pF, RL = 500Ω, Figures 10 and 11 tHZ Driver Disable from Output High 150 ns CL = 50pF, RL = 500Ω, Figures 8 and 9 tLZ Driver Disable from Output Low 150 ns CL = 50pF, RL = 500Ω, Figures 10 and 11 tOZV Shutdown to Driver Output Valid 3500 ns CL = 50pF, RL = 500Ω 600 ns Notes 3 and 4 |tPLH-tPHL| tSHDN Time to Shutdown 50 200 RECEIVER AC CHARACTERISTICS freq Data Signaling Rate 250 kbps 1/tUI, Duty Cycle 40 to 60% tPLH Receiver Propagation Delay (Low to High) 200 ns VID = +/-2V, CL = 15pF, Figures 12 and 13 tPHL Receiver Propagation Delay (High to Low) 200 ns VID = +/-2V, CL = 15pF, Figures 12 and 13 skew Receiver Propagation Delay Skew 30 ns VID = +/-2V, CL = 15pF, Figures 12 and 13 skew = |tPLH-tPHL| tR Receiver Output Rise Time 3 6 ns CL = 15pF, Figure 12 tF Receiver Output Fall Time 3 6 ns CL = 15pF, Figure 12 tZH Receiver Enable to Output High 50 ns CL = 15pF, Figure 14 tZL Receiver Enable to Output Low 50 ns CL = 15pF, Figure 14 tHZ Receiver Disable from Output High 50 ns CL = 15pF, Figure 14 tLZ Receiver Disable from Output Low 50 ns CL = 15pF, Figure 14 tZH(SHDN) Shutdown to Receiver Output Valid High 3500 ns CL = 15pF, Figure 14 tZL(SHDN) Shutdown to Receiver Output Valid Low 3500 ns CL = 15pF, Figure 14 6 XR3170E-3178E 3.3V HIGH SPEED RS-485/RS-422 TRANSCEIVERS WITH 1/8th UNIT LOAD REV. 1.0.0 UNLESS OTHERWISE NOTED: VCC = +3.0V TO +3.6V WITH TA FROM -40OC TO +85OC. TYPICAL VALUES ARE AT VCC = +3.3V AND 25OC. SYMBOL tSHDN PARAMETERS Time to Shutdown MIN. TYP. MAX. UNITS 50 200 600 ns CONDITIONS Notes 3 and 4 XR3173E, XR3174E and XR3175E DRIVER AC CHARACTERISTICS Max. Data Signaling Rate 500 tPLH Driver Propagation Delay (Low to High) 180 800 ns CL = 50pF, RL = 54Ω, Figures 6 and 7 tPHL Driver Propagation Delay (High to Low) 180 800 ns CL = 50pF, RL = 54Ω, Figures 6 and 7 tR Driver Rise Time 200 800 ns CL = 50pF, RL = 54Ω, Figures 6 and 7 tF Driver Fall Time 200 800 ns CL = 50pF, RL = 54Ω, Figures 6 and 7 Differential Pulse Skew 100 ns Figures 6 and 7 tZH Driver Enable to Output High 2500 ns CL = 50pF, RL = 500Ω, Figures 8 and 9 tZL Driver Enable to Output Low 2500 ns CL = 50pF, RL = 500Ω, Figures 10 and 11 tHZ Driver Disable from Output High 150 ns CL = 50pF, RL = 500Ω, Figures 8 and 9 tLZ Driver Disable from Output Low 150 ns CL = 50pF, RL = 500Ω, Figures 10 and 11 tOZV Shutdown to Driver Output Valid 3500 ns CL = 50pF, RL = 500Ω 600 ns Notes 3 and 4 |tPLH-tPHL| tSHDN Time to Shutdown kbps 1/tUI, Duty Cycle 40 to 60% freq 50 200 RECEIVER AC CHARACTERISTICS 500 kbps 1/tUI, Duty Cycle 40 to 60% freq Data Signaling Rate tPLH Receiver Propagation Delay (Low to High) 200 ns VID = +/-2V, CL = 15pF, Figures 12 and 13 tPHL Receiver Propagation Delay (High to Low) 200 ns VID = +/-2V, CL = 15pF, Figures 12 and 13 skew Receiver Propagation Delay Skew 30 ns VID = +/-2V, CL = 15pF, Figures 12 and 13 skew = |tPLH-tPHL| tR Receiver Output Rise Time 3 6 ns CL = 15pF tF Receiver Output Fall Time 3 6 ns CL = 15pF tZH Receiver Enable to Output High 50 ns CL = 15pF, Figure 14 tZL Receiver Enable to Output Low 50 ns CL = 15pF, Figure 14 tHZ Receiver Disable from Output High 50 ns CL = 15pF, Figure 14 7 XR3170E-3178E 3.3V HIGH SPEED RS-485/RS-422 TRANSCEIVERS WITH 1/8th UNIT LOAD REV. 1.0.0 UNLESS OTHERWISE NOTED: VCC = +3.0V TO +3.6V WITH TA FROM -40OC TO +85OC. TYPICAL VALUES ARE AT VCC = +3.3V AND 25OC. SYMBOL PARAMETERS MIN. TYP. MAX. UNITS CONDITIONS tLZ Receiver Disable from Output Low 50 ns CL = 15pF, Figure 14 tZH(SHDN) Shutdown to Receiver Output Valid High 3500 ns CL = 15pF, Figure 14 tZL(SHDN) Shutdown to Receiver Output Valid Low 3500 ns CL = 15pF, Figure 14 600 ns Notes 3 and 4 tSHDN Time to Shutdown 50 200 XR3176E, XR3177E and XR3178E DRIVER AC CHARACTERISTICS freq Max. Data Signaling Rate 20 tPLH Driver Propagation Delay (Low to High) 4 12 40 ns CL = 50pF, RL = 54Ω, Figures 6 and 7 tPHL Driver Propagation Delay (High to Low) 4 12 40 ns CL = 50pF, RL = 54Ω, Figures 6 and 7 tR Driver Rise Time 2 3 10 ns CL = 50pF, RL = 54Ω, Figures 6 and 7 tF Driver Fall Time 2 3 10 ns CL = 50pF, RL = 54Ω, Figures 6 and 7 5 ns Figures 6 and 7 |tPLH-tPHL| Mbps 1/tUI, Duty Cycle 40 to 60% Differential Pulse Skew tZH Driver Enable to Output High 150 ns CL = 50pF, RL = 500Ω, Figures 8 and 9 tZL Driver Enable to Output Low 150 ns CL = 50pF, RL = 500Ω, Figures 10 and 11 tHZ Driver Disable from Output High 150 ns CL = 50pF, RL = 500Ω, Figures 8 and 9 tLZ Driver Disable from Output Low 150 ns CL = 50pF, RL = 500Ω, Figures 10 and 11 tOZV Shutdown to Driver Output Valid 3500 ns CL = 50pF, RL = 500Ω 600 ns Notes 3 and 4 tSHDN Time to Shutdown 50 200 RECEIVER AC CHARACTERISTICS freq Data Signaling Rate 20 Mbps 1/tUI, Duty Cycle 40 to 60% tPLH Receiver Propagation Delay (Low to High) 4 22 40 ns VID = +/-2V, CL = 15pF, Figures 12 and 13 tPHL Receiver Propagation Delay (High to Low) 4 22 40 ns VID = +/-2V, CL = 15pF, Figures 12 and 13 skew Receiver Propagation Delay Skew 5 ns VID = +/-2V, CL = 15pF, Figures 12 and 13 skew = |tPLH-tPHL| tR Receiver Output Rise Time 3 8 6 ns CL = 15pF XR3170E-3178E 3.3V HIGH SPEED RS-485/RS-422 TRANSCEIVERS WITH 1/8th UNIT LOAD REV. 1.0.0 UNLESS OTHERWISE NOTED: VCC = +3.0V TO +3.6V WITH TA FROM -40OC TO +85OC. TYPICAL VALUES ARE AT VCC = +3.3V AND 25OC. SYMBOL PARAMETERS MIN. TYP. MAX. UNITS CONDITIONS 3 6 ns CL = 15pF tF Receiver Output Fall Time tZH Receiver Enable to Output High 50 ns CL = 15pF, Figure 14 tZL Receiver Enable to Output Low 50 ns CL = 15pF, Figure 14 tHZ Receiver Disable from Output High 50 ns CL = 15pF, Figure 14 tLZ Receiver Disable from Output Low 50 ns CL = 15pF, Figure 14 tZH(SHDN) Shutdown to Receiver Output Valid High 3500 ns CL = 15pF, Figure 14 tZL(SHDN) Shutdown to Receiver Output Valid Low 3500 ns CL = 15pF, Figure 14 600 ns Notes 3 and 4 tSHDN Time to Shutdown 50 200 NOTE: 1. Change in Magnitude of Differential Output Voltage and Change in Magnitude of Common Mode Output Voltage are the changes in output voltage when DI input changes state. 2. Except devices which do not have DE or RE inputs. 3. The transceivers are put into shutdown by bringing RE High and DE Low simultaneously for at least 600ns. If the control inputs are in this state for less than 50ns, the device is guaranteed not enter shutdown. If the enable inputs are held in this state for at least 600ns the device is assured to be in shutdown. Note that the receiver and driver enable times increase during shutdown. 4. Guaranteed by design and bench characterization. 9 XR3170E-3178E 3.3V HIGH SPEED RS-485/RS-422 TRANSCEIVERS WITH 1/8th UNIT LOAD REV. 1.0.0 FIGURE 3. DRIVER DC TEST CIRCUIT RL/2 DI VOD D RL/2 VOC VCC FIGURE 4. DRIVER COMMON MODE LOAD TEST DE = 3.3V 375Ω A/Y DI = 0 or Vcc D 60Ω VOD B/Z 375Ω FIGURE 5. DRIVER SHORT CIRCUIT CURRENT LIMIT TEST DE = 0 or Vcc DI = 0 or Vcc A/Y IOSD D B/Z -7V to +12V V 10 VCM XR3170E-3178E 3.3V HIGH SPEED RS-485/RS-422 TRANSCEIVERS WITH 1/8th UNIT LOAD REV. 1.0.0 FIGURE 6. DRIVER PROPAGATION DELAY TEST CIRCUIT RL 54Ω Y DI D CL 50pF VOD Z 3.3V FIGURE 7. DRIVER PROPAGATION DELAY TIMING DIAGRAM Vcc DI Vcc/2 Vcc/2 0V Z t PLH t PHL VO 1/2VO 1/2VO Y VDIFF VY – VZ t DPLH VO+ 0V VO– t DPHL 90% 10% tF 90% 10% tR t SKEW = |t DPLH - t DPHL| FIGURE 8. DRIVER ENABLE AND DISABLE TIME TEST CIRCUIT 1 Y 0 or Vcc DI D OUT Z GENERATOR S1 CL = 50pF 50Ω 11 RL = 500Ω XR3170E-3178E 3.3V HIGH SPEED RS-485/RS-422 TRANSCEIVERS WITH 1/8th UNIT LOAD REV. 1.0.0 FIGURE 9. DRIVER ENABLE DISABLE TIMING DIAGRAM 1 Vcc DE Vcc/2 0 tZH, tZH(SHDN) OUT 0.25V VOM = (VOL + Vcc)/2 t HZ FIGURE 10. DRIVER ENABLE AND DISABLE TIME TEST CIRCUIT 2 Vcc RL = 500Ω Y 0 or Vcc DI OUT Z GENERATOR S1 D CL = 50pF 50Ω 12 0 XR3170E-3178E 3.3V HIGH SPEED RS-485/RS-422 TRANSCEIVERS WITH 1/8th UNIT LOAD REV. 1.0.0 FIGURE 11. DRIVER ENABLE AND DISABLE TIMING DIAGRAM 2 Vcc Vcc/2 DE 0 tZL, tZL(SHDN) t LZ OUT VOL VOM = (VOL + Vcc)/2 0.25V FIGURE 12. RECEIVER PROPAGATION DELAY TEST CIRCUIT A VID B R RE OUT CL 15pF FIGURE 13. RECEIVER PROPAGATION DELAY TIMING DIAGRAM +1V A B t PHL t PLH -1V VOH 1.5V VOL OUT 13 XR3170E-3178E 3.3V HIGH SPEED RS-485/RS-422 TRANSCEIVERS WITH 1/8th UNIT LOAD REV. 1.0.0 FIGURE 14. RECEIVER ENABLE AND DISABLE TIMES TEST CIRCUIT 1.5V S1 S3 A -1.5V R B S2 RE GENERATOR Vcc 1kΩ CL= 15pF 50Ω FIGURE 15. RECEIVER ENABLE AND DISABLE TIMING DIAGRAM 1 S1 is open, S2 is closed, S3 = 1.5V 3V 1.5V RE t ZH, t ZH(SHDN) VOH OUT VOH /2 0V FIGURE 16. RECEIVER ENABLE AND DISABLE TIMING DIAGRAM 2 S1 is closed, S2 is open, S3 = -1.5V 3V 1.5V RE t ZL,t ZL(SHDN) 0V VCC OUT VOL= VCC /2 VOL 14 XR3170E-3178E REV. 1.0.0 3.3V HIGH SPEED RS-485/RS-422 TRANSCEIVERS WITH 1/8th UNIT LOAD FIGURE 17. RECEIVER ENABLE AND DISABLE TIMING DIAGRAM 3 S1 is open, S2 is closed, S3 = 1.5V 3V RE 1.5V tHZ 0.25V VOH 0V OUT FIGURE 18. RECEIVER ENABLE AND DISABLE TIMING DIAGRAM 4 S1 is closed, S2 is open, S3 = -1.5V 3V RE 1.5V 0V t LZ VCC OUT 0.25V VOL 15 XR3170E-3178E 3.3V HIGH SPEED RS-485/RS-422 TRANSCEIVERS WITH 1/8th UNIT LOAD REV. 1.0.0 1.0 PRODUCT DESCRIPTION XR3170E-XR3178E is a family of advanced RS-485/RS-422 transceivers. Each contains one driver and one receiver. All devices operate from a single +3.3V supply. The XR3172E, XR3175E and XR3178E are a halfduplex design while the other devices are full-duplex designs. The control pins RE and DE feature a hotswap capability allowing live insertion without spurious data transfer. Drivers are output short-circuit current limited. Thermal-shutdown circuitry protects drivers against excessive power dissipation. When activited, the thermalshutdown circuitry forces the driver outptus into a high-impedance state. ADVANCED FAILSAFE Ordinary RS-485 differential receivers will be in an indeterminate state whenever the data bus is not being actively driven. The Advanced Failsafe feature of the XR3170E family guarantees a logic-high receiver output when the receiver inputs are open or shorted, or when they are connected to a terminated transmission line with all drivers disabled. In a terminated bus with all transmitters disabled, the receivers’ differential input voltage is pulled to 0V by the termination. The XR3170E family interprets 0V differential as a logic high with a minimum 50mV noise margin while maintaining compliance with the EIA/TIA-485 standard of +/-200mV. RECEIVER INPUT FILTERING XR3170E-XR3175E receivers incorpoprate input filtering in addition to input hysteresis. This filtering enhances noise immunity with differential signals that have very slow rise and fall times. Receiver propagation delay increases slightly due to this filtering. XR3176E, XR3177E abd XR3178E high speed devices do not have this input filtering. HOT-SWAP CAPABILITY When Vcc is first applied the XR3170E family holds the driver enable and receiver enable inactive for approximately 10 microseconds. During power ramp-up other system IC’s may drive unpredictable values. Hot-swap capability prevents the XR3170E family from driving any output signal until power has stabilized. After the initial power-up sequence, the hot-swap circuit becomes transparent and driver enable and receiver enable resume their normal functions and timings. If circuit boards are inserted into an energized backplane (commonly called "live insertion" or "hot-swap") power may suddenly be applied to all circuits. Without the hot-swap capability, this situation could improperly enable the transceiver’s driver or receiver, driving invalid data onto shared busses and possibly causing driver contention or device damage. +/-15kV ESD PROTECTION ESD protection structures are incorporated on all pins to protect against electrostatic discharges encountered during handling and assembly. The driver outputs and receiver inputs of the XR3170E family have extra protection against static electricity. Exar uses state of the art structures to protect these pins against ESD of +/-15kV without damage. The ESD structures withstand high ESD in all states: normal operation, shutdown and powered down. After an ESD event, the XR3170E-XR3178E keep operating without latch-up or damage. ESD protection can be tested in various ways. The transmitter outputs and receiver inputs of the XR3170EXR3178E are characterized for protection to the following limits: ■ +/-15kV using the Human Body Model ■ +/-8kV using the Contact Discharge Model ■ +/-15kV Air-gap Discharge Model ESD TEST CONDITIONS ESD performance depends on a variety of conditions. Contact Exar for a reliability report that documents test setup, methodology and results. 16 XR3170E-3178E REV. 1.0.0 3.3V HIGH SPEED RS-485/RS-422 TRANSCEIVERS WITH 1/8th UNIT LOAD 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 XR3170E family helps you design equipment to meet IEC 61000-4-2, without sacrificing board-space and cost for external ESD-protection components. The major differences between tests done using the Human body model and IEC 61000-4-2 is a higher peak current in IEC 61000-4-2. 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 of human body model. The air-gap test involves approaching the device with a charged probe. The contact discharge method connects the probe to the device before the probe is energized. MACHINE MODEL The machine model for ESD tests all pins using a 200pF storage capacitor and zero discharge resistance. The objective is to emulate the stress caused when I/O pins are contacted by handling equipment during test and assembly. 256 TRANSCEIVERS ON THE BUS The standard RS-485 receiver input impedance is 12k Ohms (1 unit load). A standard driver can drive up to 32 unit loads. The XR3170E family of transceivers have only a 1/8th unit load receiver input impedance of 96k Ohms, thereby allowing eight times as many, up to 256, transceivers to be connected in parallel on a communication line. Any combination of these devices and other RS-485 transceivers up to a total of 32 unit loads may be connected to the line. LOW POWER SHUTDOWN MODE Low-power shutdown mode is initiated by bringing both RE high and DE low simultaneously. While in shutdown devices draw less than 1µA of supply current. DE and RE may be tied together and driven by a single control signal. Devices are guaranteed not to enter shutdown if RE is high and DE is low for less than 50ns. If the inputs are in this state for at least 600ns, the parts will enter shutdown. Enable times tZH and tZL apply when the part is not in low-power shutdown state. Enable times tZH(SHDN) and tZL(SHDN) apply when the parts are shutdown. The drivers and receivers take longer to become enabled from low-power shutdown tZH(SHDN) and tZL(SHDN) than from driver / receiver disable mode (tZH and tZL). DRIVER OUTPUT PROTECTION Two mechanisms prevent excessive output current and power dissipation caused by faults or by bus contention. First, a driver current limit on the output stage provides immediate protection against short circuits over the whole common-mode voltage range. Second, a thermal-shutdown circuit forces the driver outputs into a high-impedance state if junction temperature becomes excessive. LINE LENGTH The RS-485/RS-422 standard covers line lengths up to 4000ft. Maximum achievable line length is a function of signal attenuation and noise. Termination prevents signal reflections by eliminating the impedance mismatches on a transmission line. Line termination is generaly used if rise and fall times are shorter than the round-trip signal propagation time 17 XR3170E-3178E 3.3V HIGH SPEED RS-485/RS-422 TRANSCEIVERS WITH 1/8th UNIT LOAD REV. 1.0.0 2.0 FUNCTION TABLES TABLE 1: FULL DUPLEX 14 PIN - XR3170E, XR3173E AND XR3176E TRANSMITTING Inputs Outputs RE DE DI Y Z X 1 1 1 0 X 1 0 0 1 0 0 X High-Z 1 0 X Shutdown TABLE 2: FULL DUPLEX 8 PIN - XR3171E, XR3174E AND XR3177E TRANSMITTING Input Outputs DI Y Z 1 1 0 0 0 1 TABLE 3: HALF DUPLEX 8 PIN - XR3172E, XR2175E AND XR3178E TRANSMITTING Inputs Outputs RE DE DI A B X 1 1 1 0 X 1 0 0 1 0 0 X High-Z 1 0 X Shutdown 18 XR3170E-3178E 3.3V HIGH SPEED RS-485/RS-422 TRANSCEIVERS WITH 1/8th UNIT LOAD REV. 1.0.0 TABLE 4: FULL DUPLEX 14 PIN - XR3170E, XR3173E AND XR3176E RECEIVING Inputs Ouptut RE DE VA - VB RO 0 X ≥ -50mV 1 0 X ≤ -200mV 0 0 X Open/Shorted 1 1 1 X High-Z 1 0 X Shutdown TABLE 5: FULL DUPLEX 8 PIN - XR3171E, XR3174E AND XR3177E RECEIVING Inputs Output VA - VB RO ≥ -50mV 1 ≤ -200mV 0 Open/Shorted 1 TABLE 6: HALF DUPLEX 8 PIN - XR3172E, XR2175E AND XR3178E RECEIVING Inputs Output RE DE VA - VB RO 0 X ≥ -50mV 1 0 X ≤ -200mV 0 0 X Open/Shorted 1 1 1 X High-Z 1 0 X Shutdown Note: Receiver inputs -200mV < VA - VB < -50mV should be considered indeterminate. 19 XR3170E-3178E 3.3V HIGH SPEED RS-485/RS-422 TRANSCEIVERS WITH 1/8th UNIT LOAD REV. 1.0.0 3.0 PRODUCT SELECTOR GUIDE TABLE 7: SELECTION GUIDE DATA RATE RECEIVER SHUTDOWN AND DRIVER ENABLE PART NUMBER DUPLEX XR3170E Full 250k Yes XR3171E Full 250k XR3172E Half XR3173E TRANS ON BUS FOOT-PRINT Yes 256 SN75180 No No 256 SN75179 250k Yes Yes 256 SN75176 Full 500k Yes Yes 256 SN75180 XR3174E Full 500k No No 256 SN75179 XR3175E Half 500k Yes Yes 256 SN75176 XR3176E Full 20M Yes Yes 256 SN75180 XR3177E Full 20M No No 256 SN75179 XR3178E Half 20M Yes Yes 256 SN75176 BPS 20 XR3170E-3178E REV. 1.0.0 3.3V HIGH SPEED RS-485/RS-422 TRANSCEIVERS WITH 1/8th UNIT LOAD 4.0 TYPICAL APPLICATIONS: H alf-D uplex N etw ork RT STUB RT Bi-Directional Full-Duplex Network Point to Multi-point with Repeater Repeater (optional) 21 XR3170E-3178E 3.3V HIGH SPEED RS-485/RS-422 TRANSCEIVERS WITH 1/8th UNIT LOAD PACKAGE DIMENSIONS (14 PIN NSOIC) 22 REV. 1.0.0 XR3170E-3178E REV. 1.0.0 3.3V HIGH SPEED RS-485/RS-422 TRANSCEIVERS WITH 1/8th UNIT LOAD PACKAGE DIMENSIONS (8 PIN NSOIC) 23 XR3170E-3178E 3.3V HIGH SPEED RS-485/RS-422 TRANSCEIVERS WITH 1/8th UNIT LOAD REV. 1.0.0 REVISION HISTORY DATE REVISION 12/03/09 1.0.0 DESCRIPTION Production Release. NOTICE EXAR Corporation reserves the right to make changes to the products contained in this publication in order to improve design, performance or reliability. EXAR Corporation assumes no responsibility for the use of any circuits described herein, conveys no license under any patent or other right, and makes no representation that the circuits are free of patent infringement. Charts and schedules contained here in are only for illustration purposes and may vary depending upon a user’s specific application. While the information in this publication has been carefully checked; no responsibility, however, is assumed for inaccuracies. EXAR Corporation does not recommend the use of any of its products in life support applications where the failure or malfunction of the product can reasonably be expected to cause failure of the life support system or to significantly affect its safety or effectiveness. Products are not authorized for use in such applications unless EXAR Corporation receives, in writing, assurances to its satisfaction that: (a) the risk of injury or damage has been minimized; (b) the user assumes all such risks; (c) potential liability of EXAR Corporation is adequately protected under the circumstances. Copyright 2009 EXAR Corporation Datasheet December 2009. Send your UART technical inquiry with technical details to hotline: uarttechsupport@exar.com. Reproduction, in part or whole, without the prior written consent of EXAR Corporation is prohibited. 24