LTC485 Low Power RS485 Interface Transceiver Features n n n n n n n n n n n Description Low Power: ICC = 300A Typ Designed for RS485 Interface Applications Single 5V supply -7V to 12V Bus Common Mode Range Permits 7V Ground Difference Between Devices on the Bus Thermal Shutdown Protection Power-Up/Down Glitch-Free Driver Outputs Permit Live Insertion or Removal of Transceiver Driver Maintains High Impedance in Three-State or with the Power Off Combined Impedance of a Driver Output and Receiver Allows Up to 32 Transceivers on the Bus 70mV Typical Input Hysteresis 30ns Typical Driver Propagation Delays with 5ns Skew for Up to 2.5MB Operation Pin Compatible with 60V Protected LT1785 and 52Mbps LTC1685 Applications n n The LTC(R)485 is a low power differential bus/line transceiver designed for multipoint data transmission standard RS485 applications with extended common mode range (12V to -7V). It also meets the requirements of RS422. The CMOS design offers significant power savings over its bipolar counterpart without sacrificing ruggedness against overload of ESD damage. The driver and receiver feature three-state outputs, with the driver outputs maintaining high impedance over the entire common mode range. Excessive power dissipation caused by bus contention or faults is prevented by a thermal shutdown circuit which forces the driver outputs into a high impedance state. The receiver has a fail-safe feature which guarantees a high output state when the inputs are left open. The LTC485 is fully specified over the commercial and extended industrial temperature range. L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Low Power RS485/RS422 Transceiver Level Translator Typical Application Driver Outputs RO1 R VCC1 RE1 Rt DE1 DI1 RO2 D R A GND1 VCC2 Rt RE2 DE2 DI2 D B GND2 485 TA01a 485 TA01b 485fi 1 LTC485 Absolute Maximum Ratings Pin Configuration (Note 1) TOP VIEW Supply Voltage...........................................................12V Control Input Voltages......................-0.5V to VCC + 0.5V Driver Input Voltage..........................-0.5V to VCC + 0.5V Driver Output Voltage...............................................14V Receiver Input Voltage.............................................14V Receiver Output Voltages................. -0.5V to VCC + 0.5V Operating Temperature Range LTC485I......................................... -40C TA 85C LTC485C............................................ 0C TA 70C LTC485M..................................... -55C TA 125C Lead Temperature (Soldering, 10 sec)................... 300C RO 1 R RE 2 DE 3 D DI 4 N8 PACKAGE 8-LEAD PLASTIC DIP 8 VCC 7 B 6 A 5 GND S8 PACKAGE 8-LEAD PLASTIC SOIC J8 PACKAGE 8-LEAD CERAMIC DIP TJMAX = 125C, JA = 100C/W (N) TJMAX = 150C, JA = 150C/W (S) TJMAX = 155C, JA = 100C/W (J) Order Information LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC485CN8#PBF LTC485CN8#TRPBF LTC485CN8 8-Lead Plastic DIP 0C to 70C LTC485CS8#PBF LTC485CS8#TRPBF 485 8-Lead Plastic SOIC 0C to 70C LTC485IN8#PBF LTC485IN8#TRPBF LTC485IN8 8-Lead Plastic DIP -40C to 85C LTC485IS8#PBF LTC485IS8#TRPBF 485I 8-Lead Plastic SOIC -40C to 85C LEAD BASED FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC485CN8 LTC485CN8#TR LTC485CN8 8-Lead Plastic DIP 0C to 70C LTC485CS8 LTC485CS8#TR 485 8-Lead Plastic SOIC 0C to 70C LTC485IN8 LTC485IN8#TR LTC485IN8 8-Lead Plastic DIP -40C to 85C LTC485IS8 LTC485IS8#TR 485I 8-Lead Plastic SOIC -40C to 85C LTC485MJ8 LTC485MJ8#TR LTC485MJ8 8-Lead Ceramic DIP -55C to 125C Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. For more information on lead free part marking, go to: http://www.linear.com/leadfree/ For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/ Electrical Characteristics The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. VCC = 5V 5%, unless otherwise noted. (Notes 2 and 3) SYMBOL PARAMETER CONDITIONS MIN VOD1 Differential Driver Output Voltage (Unloaded) IO = 0 l VOD2 Differential Driver Output Voltage (with Load) R = 50 (RS422) R = 27 (RS485), Figure 1 l l VOD Change in Magnitude of Driver Differential Output Voltage for Complementary States R = 27 or R = 50, Figure 1 VOC Driver Common Mode Output Voltage |VOC| Change in Magnitude of Driver Common Mode Output Voltage for Complementary States TYP MAX 5 2 1.5 UNITS V 5 V V l 0.2 V R = 27 or R = 50, Figure 1 l 3 V R = 27 or R = 50, Figure 1 l 0.2 V 485fi 2 LTC485 Electrical Characteristics The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. VCC = 5V 5%, unless otherwise noted. (Notes 2 and 3) SYMBOL PARAMETER CONDITIONS MIN VIH Input High Voltage DE, DI, RE l VIL Input Low Voltage DE, DI, RE l 0.8 l 2 A l l 1 -0.8 mA mA 0.2 V IIN1 Input Current DE, DI, RE IIN2 Input Current (A, B) DE = 0, VCC = 0V or 5.25V VTH Differential Input Threshold Voltage for Receiver -7V VCM 12V l VTH Receiver Input Hysteresis VCM = 0V l VOH Receiver Output High Voltage IO = -4mA, VID = 200mV l VIN = 12V VIN = -7V TYP MAX 2 UNITS V -0.2 70 V mV 3.5 V VOL Receiver Output Low Voltage IO = 4mA, VID = -200mV l 0.4 V IOZR Three-State (High Impedance) Output Current at Receiver VCC = Max, 0.4V VO 2.4V l 1 A RIN Receiver Input Resistance -7V VCM 12V l 12 k Switching Characteristics The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. VCC = 5V 5%, unless otherwise noted. (Notes 2 and 3) SYMBOL PARAMETER CONDITIONS MIN ICC Supply Current No Load, Pins 2, 3, 4 = 0V or 5V IOSD1 Driver Short-Circuit Current, VOUT = HIGH VO = - 7V l IOSD2 Driver Short-Circuit Current, VOUT = LOW VO = 10V l IOSR Receiver Short-Circuit Current 0V VO VCC l 7 tPLH Driver Input to Output RDIFF = 54, CL1 = CL2 = 100pF, (Figures 3 and 5) l 10 30 l 10 30 50 ns 5 10 ns Outputs Enabled Outputs Disabled TYP MAX UNITS 500 300 900 500 A A 35 100 250 mA 35 100 250 mA 85 mA 50 ns l l tPHL Driver Input to Output tSKEW Driver Output to Output tr, tf Driver Rise or Fall Time 15 25 ns tZH Driver Enable to Output High CL = 100pF (Figures 4 and 6) S2 Closed l 40 70 ns tZL Driver Enable to Output Low CL = 100pF (Figures 4 and 6) S1 Closed l 40 70 ns tLZ Driver Disable Time from Low CL = 15pF (Figures 4 and 6) S1 Closed l 40 70 ns 40 70 ns 90 200 ns 90 200 l l 3 tHZ Driver Disable Time from High CL = 15pF (Figures 4 and 6) S2 Closed l tPLH Receiver Input to Output RDIFF = 54, CL1 = CL2 = 100pF, (Figures 3 and 7) l 30 l 30 tPHL tSKD |tPLH - tPHL| Differential Receiver Skew l 13 ns ns tZL Receiver Enable to Output Low CRL = 15pF (Figures 2 and 8) S1 Closed l 20 50 ns tZH Receiver Enable to Output High CRL = 15pF (Figures 2 and 8) S2 Closed l 20 50 ns tLZ Receiver Disable from Low CRL = 15pF (Figures 2 and 8) S1 Closed l 20 50 ns tHZ Receiver Disable from High CRL = 15pF (Figures 2 and 8) S2 Closed l 20 50 ns Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: All currents into device pins are positive; all currents out ot device pins are negative. All voltages are referenced to device ground unless otherwise specified. Note 3: All typicals are given for VCC = 5V and TA = 25C. Note 4: The LTC485 is guaranteed by design to be functional over a supply voltage range of 5V 10%. Data sheet parameters are guaranteed over the tested supply voltage range of 5V 5%. 485fi 3 LTC485 Typical Performance Characteristics Receiver Output Low Voltage vs Output Current -18 TA = 25C 32 OUTPUT CURRENT (mA) OUTPUT CURRENT (mA) 24 20 16 12 8 4 0 0.5 0 4.4 -12 -10 -8 -6 3.2 4 3 OUTPUT VOLTAGE (V) 5 0.5 0.4 0.3 0.2 2.4 TA = 25C 56 48 40 32 24 16 0 125 0 1 1.8 1.7 40 30 20 10 485 G07 25 50 0 75 TEMPERATURE (C) 100 1.64 TA = 25C -84 -72 -60 -48 -36 -24 0 125 TTL Input Threshold vs Temperature -12 4 -25 485 G06 1.63 INPUT THRESHOLD VOLTAGE (V) 50 3 2 OUTPUT VOLTAGE (V) 1.9 1.5 -50 4 3 2 OUTPUT VOLTAGE (V) -96 60 1 2.0 1.6 -108 70 0 2.1 Driver Output High Voltage vs Output Current OUTPUT CURRENT (mA) OUTPUT CURRENT (mA) 80 125 2.2 485 G05 Driver Output Low Voltage vs Output Current TA = 25C 100 RI = 54 2.3 485 G04 90 25 50 0 75 TEMPERATURE (C) Driver Differential Output Voltage vs Temperature 8 0.1 100 -25 485 G03 DIFFERENTIAL VOLTAGE (V) OUTPUT CURRENT (mA) OUTPUT VOLTAGE (V) 0.7 0.6 0 3.0 -50 2 Driver Differential Output Voltage vs Output Current 64 25 50 0 75 TEMPERATURE (C) 3.6 -2 72 -25 3.8 485 G02 I = 8mA 0 -50 4.0 3.4 Receiver Output Low Voltage vs Temperature 0.8 4.2 -4 485 G01 0.9 I = 8mA 4.6 -14 0 2.0 1.5 1.0 OUTPUT VOLTAGE (V) 4.8 TA = 25C -16 28 Receiver Output High Voltage vs Temperature OUTPUT VOLTAGE (V) 36 Receiver Output High Voltage vs Output Current 0 1 3 2 OUTPUT VOLTAGE (V) 4 485 G08 1.62 1.61 1.60 1.59 1.58 1.57 1.56 1.55 -50 -25 25 50 0 75 TEMPERATURE (C) 100 125 485 G09 485fi 4 LTC485 Typical Performance Characteristics Driver Skew vs Temperature Supply Current vs Temperature 5.4 640 7.0 4.8 580 6.5 4.2 520 6.0 3.6 5.5 5.0 3.0 2.4 4.5 1.8 4.0 1.2 3.5 0.6 3.0 -50 -25 25 50 0 75 TEMPERATURE (C) 100 125 SUPPLY CURRENT (A) 7.5 TIME (ns) TIME (ns) Receiver |tPLH - tPHL| vs Temperature 0 -50 DRIVER ENABLED 460 400 340 DRIVER DISABLED 280 220 160 -25 25 50 0 75 TEMPERATURE (C) 485 G10 100 125 100 -50 -25 0 25 50 75 TEMPERATURE (C) 485 G11 100 125 485 G12 Pin Functions RO (Pin 1): Receiver Output. If the receiver output is enabled (RE low), then if A > B by 200mV, RO will be high. If A < B by 200mV, then RO will be low. RE (Pin 2): Receiver Output Enable. A low enables the receiver output, RO. A high input forces the receiver output into a high impedance state. DE (Pin 3): Driver Outputs Enable. A high on DE enables the driver output. A and B, and the chip will function as a line driver. A low input will force the driver outputs into a high impedance state and the chip will function as a line receiver. DI (Pin 4): Driver Input. If the driver outputs are enabled (DE high), then a low on DI forces the outputs A low and B high. A high on DI with the driver outputs enabled will force A high and B low. GND (Pin 5): Ground Connection. A (Pin 6): Driver Output/Receiver Input. B (Pin 7): Driver Output/Receiver Input. VCC (Pin 8): Positive Supply; 4.75 < VCC < 5.25. 485fi 5 LTC485 Test Circuits A R RECEIVER OUTPUT VOD CRL 15pF VOC R S1 TEST POINT 1k 1k VCC S2 485 F02 B 485 F01 Figure 1. Driver DC Test Load Figure 2. Receiver Timing Test Load 3V DE A DI CL1 RDIFF B CL2 A S1 RO B RE VCC 500 OUTPUT UNDER TEST S2 15pF CL 485 F04 485 F03 Figure 3. Driver/Receiver Timing Test Circuit Figure 4. Driver Timing Test Load #2 Switching Time Waveforms 3V 1.5V DI f = 1MHz, tr 10ns, tf 10ns 0V tPLH B A VO 0V -VO 1.5V 1/2 VO tPLH VO tSKEW 1/2 VO 10% 80% tSKEW 90% VDIFF = V(A) - V(B) tr 20% tf 485 F05 Figure 5. Driver Propagation Delays 485fi 6 LTC485 Switching Time Waveforms 3V 1.5V DI tLZ tZL 5V A, B 2.3V OUTPUT NORMALLY LOW 0.5V 2.3V OUTPUT NORMALLY HIGH 0.5V VOL A, B 1.5V f = 1MHz, tr 10ns, tf 10ns 0V VOH 0V tHZ tZH 485 F06 Figure 6. Driver Enable and Disable Times R VOH 1.5V VOL f = 1MHz, tr 10ns, tf 10ns tPHL VOD2 A, B -VOD2 0V 1.5V OUTPUT tPLH INPUT 485 F07 Figure 7. Receiver Propagation Delays 3V 1.5V RE R tLZ tZL 5V R 0V 1.5V f = 1MHz, tr 10ns, tf 10ns 0V 1.5V OUTPUT NORMALLY LOW 0.5V 1.5V OUTPUT NORMALLY HIGH 0.5V tHZ tZH 485 F08 Figure 8. Receiver Enable and Disable Times Function Tables LTC485 Receiving LTC485 Transmitting INPUTS INPUTS OUTPUTS OUTPUTS RE DE DI LINE CONDITION X 1 1 No Fault X 1 0 No Fault 1 0 0 0 -0.2V 0 X 0 X X Z Z 0 0 Inputs Open 1 X 1 X Fault Z Z 1 0 X Z B 0 A RE DE A-B R 1 0 0 0.2V 1 485fi 7 LTC485 Applications Information Basic Theory of Operation Previous RS485 transceivers have been designed using bipolar technology because the common mode range of the device must extend beyond the supplies and the device must be immune to ESD damage and latchup. Unfortunately, the bipolar devices draw a large amount of supply current, which is unacceptable for the numerous applications that require low power consumption. The LTC485 is the first CMOS RS485/RS422 transceiver which features ultralow power consumption without sacrificing ESD and latchup immunity. The LTC485 uses a proprietary driver output stage, which allows a common-mode range that extends beyond the power supplies while virtually eliminating latchup and providing excellent ESD protection. Figure 9 shows the LTC485 output stage while Figure 10 shows a conventional CMOS output stage. When the conventional CMOS output stage of Figure 10 enters a high impedance state, both the P-channel (P1) and the N-channel (N1) are turned off. If the output is then driven above VCC or below ground, the P + /N-well diode (D1) or the N + /P-substrate diode (D2) respectively will turn on and clamp the output to the supply. Thus, the output stage is no longer in a high impedance state and is not able to meet the RS485 common mode range requirement. In addition, the large amount of current flowing through either diode will induce the well known CMOS latchup condition, which could destroy the device. The LTC485 output stage of Figure 9 eliminates these problems by adding two Schottky diodes, SD3 and SD4. The Schottky diodes are fabricated by a proprietary modification to the standard N-well CMOS process. When the output stage is operating normally, the Schottky diodes are forward biased and have a small voltage drop across them. When the output is in the high impedance state and is driven above VCC or below ground, the parasitic diodes D1 or D2 still turn on, but SD3 or SD4 will reverse bias and prevent current from flowing into the N-well or the substrate. Thus, the high impedance state is maintained even with the output voltage beyond the supplies. With no minority carrier current flowing into the N-well or substrate, latchup is virtually eliminated under power-up or power-down conditions. VCC VCC SD3 P1 P1 D1 OUTPUT LOGIC SD4 N1 D1 N1 D2 485 F09 Figure 9. LTC485 Output Stage OUTPUT LOGIC D2 485 F10 Figure 10. Conventional CMOS Output Stage 485fi 8 LTC485 Applications Information The LTC485 output stage will maintain a high impedance state until the breakdown of the N-channel or P-channel is reached when going positive or negative respectively. The output will be clamped to either VCC or ground by a Zener voltage plus a Schottky diode drop, but this voltage is way beyond the RS485 operating range. This clamp protects the MOS gates from ESD voltages well over 2000V. Because the ESD injected current in the N-well or substrate consists of majority carriers, latchup is prevented by careful layout techniques. Propagation Delay Many digital encoding schemes are dependent upon the difference in the propagation delay times of the driver and the receiver. Using the test circuit of Figure 13, Figures 11 and 12 show the typical LTC485 receiver propagation delay. The receiver delay times are: |tPLH - tPHL| = 9ns Typ, VCC = 5V The driver skew times are: Skew = 5ns Typ, VCC = 5V 10ns Max, VCC = 5V, TA = -40C to 85C A A DRIVER OUTPUTS DRIVER OUTPUTS B RECEIVER RO OUTPUTS B RECEIVER RO OUTPUTS 485 F11 485 F12 Figure 11. Receiver tPHL Figure 12. Receiver tPLH 100pF TTL IN tr, tf < 6ns D BR R R 100 RECEIVER OUT 485 F13 100pF Figure 13. Receiver Propagation Delay Test Circuit 485fi 9 LTC485 Applications Information LTC485 Line Length vs Data Rate The maximum line length allowable for the RS422/RS485 standard is 4000 feet. Figures 17 and 18 show that the LTC485 is able to comfortably drive 4000 feet of wire at 110kHz. 100 C A LTC485 D B NOISE GENERATOR TTL IN RO LTC485 TTL OUT COMMON MODE VOLTAGE (A + B)/2 4000 FT 26AWG TWISTED PAIR DI 485 F14 Figure 14. Line Length Test Circuit 485 F17 Figure 17. System Common Mode Voltage at 110kHz Using the test circuit in Figure 14, Figures 15 and 16 show that with ~20VP-P common mode noise injected on the line, The LTC485 is able to reconstruct the data stream at the end of 4000 feet of twisted pair wire. RO COMMON MODE VOLTAGE (A - B) DI RO COMMON MODE VOLTAGE (A + B)/2 485 F18 Figure 18. System Differential Voltage at 110kHz DI 485 F15 When specifying line length vs maximum data rate the curve in Figure 19 should be used. Figure 15. System Common Mode Voltage at 19.2kHz CABLE LENGTH (FT) 10k RO DIFFERENTIAL VOLTAGE A - B 1k 100 DI 10 10k 485 F16 Figure 16. System Differential Voltage at 19.2kHz 100k 1M 2.5M MAXIMUM DATA RATE 10M 485 F19 Figure 19. Cable Length vs Maximum Data Rate 485fi 10 LTC485 Typical Application Typical RS485 Network Rt Rt 485 TA02 Package Description J8 Package 8-Lead CERDIP (Narrow .300 Inch, Hermetic) (Reference LTC DWG # 05-08-1110) CORNER LEADS OPTION (4 PLCS) .023 - .045 (0.584 - 1.143) HALF LEAD OPTION .045 - .068 (1.143 - 1.650) FULL LEAD OPTION .005 (0.127) MIN .405 (10.287) MAX 8 7 6 5 .025 (0.635) RAD TYP .220 - .310 (5.588 - 7.874) 1 .300 BSC (7.62 BSC) 2 3 4 .200 (5.080) MAX .015 - .060 (0.381 - 1.524) .008 - .018 (0.203 - 0.457) 0 - 15 NOTE: LEAD DIMENSIONS APPLY TO SOLDER DIP/PLATE OR TIN PLATE LEADS .045 - .065 (1.143 - 1.651) .014 - .026 (0.360 - 0.660) .100 (2.54) BSC .125 3.175 MIN J8 0801 485fi 11 LTC485 Package Description N8 Package 8-Lead PDIP (Narrow .300 Inch) (Reference LTC DWG # 05-08-1510) .400* (10.160) MAX 8 7 6 .300 - .325 (7.620 - 8.255) 5 .255 .015* (6.477 0.381) .065 (1.651) TYP .008 - .015 (0.203 - 0.381) 1 2 4 3 ( +.035 .325 -.015 8.255 +0.889 -0.381 .130 .005 (3.302 0.127) .045 - .065 (1.143 - 1.651) ) .120 (3.048) .020 MIN (0.508) MIN .018 .003 (0.457 0.076) .100 (2.54) BSC N8 1002 NOTE: 1. DIMENSIONS ARE INCHES MILLIMETERS *THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .010 INCH (0.254mm) S8 Package 8-Lead Plastic Small Outline (Narrow .150 Inch) (Reference LTC DWG # 05-08-1610) .050 BSC .189 - .197 (4.801 - 5.004) NOTE 3 .045 .005 8 .245 MIN .160 .005 .010 - .020 x 45 (0.254 - 0.508) NOTE: 1. DIMENSIONS IN 5 .150 - .157 (3.810 - 3.988) NOTE 3 1 RECOMMENDED SOLDER PAD LAYOUT .053 - .069 (1.346 - 1.752) 0- 8 TYP .016 - .050 (0.406 - 1.270) 6 .228 - .244 (5.791 - 6.197) .030 .005 TYP .008 - .010 (0.203 - 0.254) 7 .014 - .019 (0.355 - 0.483) TYP INCHES (MILLIMETERS) 2. DRAWING NOT TO SCALE 3. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm) 2 3 4 .004 - .010 (0.101 - 0.254) .050 (1.270) BSC SO8 0303 485fi 12 LTC485 Revision History (Revision history begins at Rev I) REV DATE DESCRIPTION PAGE NUMBER I 4/11 Removed lead free version of LTC485MJ8 from Order Information section. 2 485fi Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. 13 LTC485 Related Parts PART NUMBER DESCRIPTION COMMENTS LTC486/LTC487 Low Power Quad RS485 Drivers 110A Supply Current LTC488/LTC489 Low Power Quad RS485 Receivers 7mA Supply Current LTC490/LTC491 Low Power Full-Duplex RS485 Transceivers 300A Supply Current LTC1480 3.3V Supply RS485 Transceiver Lower Supply Voltage LTC1481 Low Power RS485 Transceiver with Shutdown Lowest Power LTC1482 RS485 Transceiver with Carrier Detect 15kV ESD, Fail-Safe LTC1483 Low Power, Low EMI RS485 Transceiver Slew Rate Limited Driver Outputs, Lowest Power LTC1484 RS485 Transceiver with Fail-Safe 15kV ESD, MSOP Package LTC1485 10Mbps RS485 Transceiver High Speed LTC1518/LTC1519 52Mbps Quad RS485 Receivers Higher Speed, LTC488/LTC489 Pin-Compatible LTC1520 LVDS-Compatible Quad Receiver 100mV Threshold, Low Channel-to-Channel Skew LTC1535 2500V Isolated RS485 Transceiver Full-Duplex, Self-Powered Using External Transformer LTC1685 52Mbps RS485 Transceiver Industry-Standard Pinout, 500ps Propagation Delay Skew LTC1686/LTC1687 52Mbps Full-Duplex RS485 Transceivers LTC490/LTC491 Pin Compatible LTC1688/LTC1689 100Mbps Quad RS485 Drivers Highest Speed, LTC486/LTC487 Pin Compatible LTC1690 Full-Duplex RS485 Transceiver with Fail-Safe 15kV ESD, LTC490 Pin Compatible LT1785/LTC1785A 60V Protected RS485 Transceivers 15kV ESD, Fail-Safe (LT1785A) LT1791/LTC1791A 60V Protected Full-Duplex RS485 Transceivers 15kV ESD, Fail-Safe (LT1791A) LTC2850/LTC2851/ LTC2852 3.3V Supply RS485 Transceivers 15kV ESD, 20Mbps, 900A Supply Current, Fail-Safe LTC2854/LTC2855 3.3V Supply RS485 Transceivers 15kV ESD, 20Mbps, 900A Supply Current, Integrated Switchable Termination LTC2856/LTC2857/ LTC2858 20Mbps RS485 Transceivers 15kV ESD, 900A Supply Current, Fail-Safe LTC2859/LTC2861 20Mbps RS485 Transceivers 15kV ESD, 900A Supply Current, Integrated Switchable Termination 485fi 14 Linear Technology Corporation LT 0411 REV I * PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 l FAX: (408) 434-0507 l www.linear.com LINEAR TECHNOLOGY CORPORATION 1994