LTC491 Differential Driver and Receiver Pair FEATURES DESCRIPTIOU n Low Power: I = 300m A Typical The LTC®491 is a low power differential bus/line trans- CC n Designed for RS485 or RS422 Applications ceiver designed for multipoint data transmission standard n Single 5V Supply RS485 applications with extended common mode range n –7V to 12V Bus Common Mode Range (12V to –7V). It also meets the requirements of RS422. Permits – 7V Ground Difference Between Devices The CMOS design offers significant power savings over its on the Bus bipolar counterpart without sacrificing ruggedness against n Thermal Shutdown Protection overload or ESD damage. n Power-Up/-Down Glitch-Free Driver Outputs Permit Live Insertion or Removal of Package The driver and receiver feature three-state outputs, with n Driver Maintains High Impedance in Three-State or the driver outputs maintaining high impedance over the with the Power Off entire common mode range. Excessive power dissipation n Combined Impedance of a Driver Output and caused by bus contention or faults is prevented by a Receiver Allows up to 32 Transceivers on the Bus thermal shutdown circuit which forces the driver outputs n 70mV Typical Input Hysteresis into a high impedance state. n 28ns Typical Driver Propagation Delays with 5ns The receiver has a fail safe feature which guarantees a high Skew for 2.5MB Operation output state when the inputs are left open. nPin Compatible with the SN75180 Both AC and DC specifications are guaranteed from 0(cid:176) C to n Available in 14-Lead PDIP and SO Packages 70(cid:176) C and 4.75V to 5.25V supply voltage range. APPLICATIOU S , LTC and LT are registered trademarks of Linear Technology Corporation. n Low Power RS485/RS422 Transceiver n Level Translator TYPICAL APPLICATIOU DE DE 4 9 5 120W 120W D DRIVER RECEIVER R 10 4000 FT 24 GAUGE TWISTED PAIR LTC491 LTC491 12 2 120W 120W R RECEIVER DRIVER D 11 4000 FT 24 GAUGE TWISTED PAIR 3 REB REB LTC491 • TA01 491fa 1

LTC491 ABSOLUTE WAXIWUW RATIUGS PACKAGE/ORDER IUFORWATIOU (Note 1) Supply Voltage (V )............................................... 12V CC ORDER PART TOP VIEW Control Input Voltages....................–0.5V to V + 0.5V CC NUMBER Control Input Currents..........................–50mA to 50mA NC 1 14 VCC Driver Input Voltages......................–0.5V to V + 0.5V R 2 R 13 NC CC LTC491CN REB 3 12 A Driver Input Currents............................–25mA to 25mA LTC491CS Driver Output Voltages .......................................... – 14V DE 4 11 B LTC491IN Receiver Input Voltages......................................... – 14V D 5 D 10 Z LTC491IS GND 6 9 Y Receiver Output Voltages ...............–0.5V to V + 0.5V CC GND 7 8 NC Operating Temperature Range LTC491C .................................................0(cid:176) C to 70(cid:176) C N PACKAGE S PACKAGE 14-LEAD PDIP 14-LEAD PLASTIC SO LTC491I.............................................. –40(cid:176) C to 85(cid:176) C TJMAX = 100(cid:176)C, q JA = 90(cid:176)C/W (N) Storage Temperature Range................. –65(cid:176) C to 150(cid:176) C TJMAX = 100(cid:176)C, q JA = 110(cid:176)C/W (S) Lead Temperature (Soldering, 10 sec)..................300(cid:176) C Consult LTC Marketing for parts specified with wider operating temperature ranges. DC ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T = 25(cid:176) C. V = 5V – 5% A CC SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS V Differential Driver Output Voltage (Unloaded) I = 0 l 5 V OD1 O V Differential Driver Output Voltage (With load) R = 50W ; (RS422) l 2 V OD2 R = 27W ; (RS485) (Figure 1) l 1.5 5 V D V Change in Magnitude of Driver Differential Output R = 27W or R = 50W (Figure 1) l 0.2 V OD Voltage for Complementary Output States V Driver Common Mode Output Voltage l 3 V OC D(cid:247) V (cid:247) Change in Magnitude of Driver Common Mode l 0.2 V OC Output Voltage for Complementary Output States V Input High Voltage D, DE, REB l 2.0 V IH V Input Low Voltage l 0.8 V IL l Input Current l – 2 m A IN1 l Input Current (A, B) V = 0V or 5.25V V = 12V l 1.0 mA IN2 CC IN V = –7V l –0.8 mA IN V Differential Input Threshold Voltage for Receiver –7V £ V £ 12V l –0.2 0.2 V TH CM D V Receiver Input Hysteresis V = 0V l 70 mV TH CM V Receiver Output High Voltage I = –4mA, V = 0.2V l 3.5 V OH O ID V Receiver Output Low Voltage I = 4mA, V = –0.2V l 0.4 V OL O ID I Three-State Output Current at Receiver V = Max 0.4V £ V £ 2.4V l – 1 m A OZR CC O I Supply Current No Load; D = GND, Outputs Enabled l 300 500 m A CC or VCC Outputs Disabled l 300 500 m A R Receiver Input Resistance –7V £ V £ 12V l 12 kW IN CM I Driver Short Circuit Current, V = High V = –7V l 100 250 mA OSD1 OUT O I Driver Short Circuit Current, V = Low V = 12V l 100 250 mA OSD2 OUT O I Receiver Short Circuit Current 0V £ V £ V l 7 85 mA OSR O CC I Driver Three-State Output Current V = –7V to 12V l – 2 – 200 m A OZ O 491fa 2

LTC491 SWITCHIUG CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T = 25(cid:176) C. V = 5V – 5% A CC SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS t Driver Input to Output R = 54W , C = C = 100pF l 10 30 50 ns PLH DIFF L1 L2 (Figures 2, 5) t Driver Input to Output l 10 30 50 ns PHL t Driver Output to Output l 5 ns SKEW t, t Driver Rise or Fall Time l 5 15 25 ns r f t Driver Enable to Output High C = 100pF (Figures 4, 6) S2 Closed l 40 70 ns ZH L t Driver Enable to Output Low C = 100pF (Figures 4, 6) S1 Closed l 40 70 ns ZL L t Driver Disable Time From Low C = 15pF (Figures 4, 6) S1 Closed l 40 70 ns LZ L t Driver Disable Time From High C = 15pF (Figures 4, 6) S2 Closed l 40 70 ns HZ L t Receiver Input to Output R = 54W , C = C = 100pF l 40 70 150 ns PLH DIFF L1 L2 t Receiver Input to Output (Figures 2, 7) l 40 70 150 ns PHL t (cid:247) t – t (cid:247) Differential Receiver Skew l 13 ns SKD PLH PHL t Receiver Enable to Output Low C = 15pF (Figures 3, 8) S1 Closed l 20 50 ns ZL L t Receiver Enable to Output High C = 15pF (Figures 3, 8) S2 Closed l 20 50 ns ZH L t Receiver Disable From Low C = 15pF (Figures 3, 8) S1 Closed l 20 50 ns LZ L t Receiver Disable From High C = 15pF (Figures 3, 8) S2 Closed l 20 50 ns HZ L Note 1: Absolute Maximum Ratings are those values beyond which the life Note 3: All typicals are given for V = 5V and temperature = 25(cid:176) C. CC of the device may be impaired. Note 2: All currents into device pins are positive; all currents out of device pins are negative. All voltages are referenced to device ground unless otherwise specified. PIU FUU CTIOU S NC (Pin 1): Not Connected. GND (Pin 6): Ground Connection. R (Pin 2): Receiver Output. If the receiver output is enabled GND (Pin 7): Ground Connection. (REB low), then if A > B by 200mV, R will be high. If A < B NC (Pin 8): Not Connected. by 200mV, then R will be low. Y (Pin 9): Driver Output. REB (Pin 3): Receiver Output Enable. A low enables the receiver output, R. A high input forces the receiver output Z (Pin 10): Driver Output. into a high impedance state. B (Pin 11): Receiver Input. DE (Pin 4): Driver Output Enable. A high on DE enables the A (Pin 12): Receiver Input. driver outputs, Y and Z. A low input forces the driver NC (Pin 13): Not Connected. outputs into a high impedance state. V (Pin 14): Positive Supply; 4.75V £ V £ 5.25V. D (Pin 5): Driver Input. If the driver outputs are enabled CC CC (DE high), then a low on D forces the driver outputs Y low and Z high. A high on D will force Y high and Z low. 491fa 3

LTC491 TYPICAL PERFORW AU CE CHARACTERISTICS Driver Output High Voltage Driver Differential Output Voltage Driver Output Low Voltage vs Output Current, T = 25(cid:176) C vs Output Current, T = 25(cid:176) C vs Output Current, T = 25(cid:176) C A A A –96 64 80 A) A) A) T (m–72 T (m 48 T (m 60 N N N E E E R R R R R R CU– 48 CU 32 CU 40 T T T U U U P P P T T T U U U O–24 O 16 O 20 0 0 0 0 1 2 3 4 0 1 2 3 4 0 1 2 3 4 OUTPUT VOLTAGE (V) OUTPUT VOLTAGE (V) OUTPUT VOLTAGE (V) LTC491 • TPC01 LTC491 • TPC02 LTC491 • TPC03 TTL Input Threshold vs Temperature Driver Skew vs Temperature Supply Current vs Temperature 1.63 5.0 350 V) E ( AG A) D VOLT1.61 ns) 4.0 mRENT ( 340 HOL1.59 ME ( 3.0 CUR330 UT THRES1.57 TI 2.0 SUPPLY 320 P N I 1.55 1.0 310 –50 0 50 100 –50 0 50 100 –50 0 50 100 TEMPERATURE ((cid:176)C ) TEMPERATURE ((cid:176)C ) TEMPERATURE ((cid:176)C ) LTC491 • TPC04 LTC491 • TPC05 LTC491 • TPC06 Driver Differential Output Voltage Receiver (cid:247) t t (cid:247) Receiver Output Low Voltage PLH PHL vs Temperature, R = 54W vs Temperature vs Temperature at I = 8mA O 2.3 7.0 0.8 V) NTIAL VOLTAGE ( 12..91 TIME (ns) 56..00 UT VOLTAGE (V) 00..46 E P R T E U F O DIF 1.7 4.0 0.2 1.5 3.0 0 –50 0 50 100 –50 0 50 100 –50 0 50 100 TEMPERATURE ((cid:176)C ) TEMPERATURE ((cid:176)C ) TEMPERATURE ((cid:176)C ) LTC491 • TPC07 LTC491 • TPC08 LTC491 • TPC09 491fa 4

LTC491 TEST CIRCUITS Y R VOD2 R VOC Z LTC491 • F01 Figure 1. Driver DC Test Load Y CL1 A D DRIVER RDIFF RECEIVER R Z CL2 B 15pF LTC491 • F02 Figure 2. Driver/Receiver Timing Test Circuit S1 1k RECEIVER V OUTPUT CC CL 1k S2 LTC491 • F03 Figure 3. Receiver Timing Test Load S1 V CC 500W OUTPUT UNDER TEST CL S2 LTC491 • F04 Figure 4. Driver Timing Test Load 491fa 5

LTC491 SWITCHIU G TIW E WAVEFORW S 3V D 1.5V f = 1MHz : tr £ 10ns : tf £ 10ns 1.5V 0V tPLH tPHL VO 50% 80% VDIFF = V(Y) – V(Z) 90% 50% –VO 10% 20% tr tf Z VO Y 1/2 VO tSKEW 1/2 VO tSKEW LTC491 • F05 Figure 5. Driver Propagation Delays 3V DE 1.5V f = 1MHz : tr £ 10ns : tr £ 10ns 1.5V 0V tZL tLZ 5V A, BVOL 2.3V OUTPUT NORMALLY LOW 0.5V A, BVOH 2.3V OUTPUT NORMALLY HIGH 0.5V 0V tZH tHZ LTC491 • F06 Figure 6. Driver Enable and Disable Times INPUT VOD2 A-B 0V f = 1MHz ; tr £ 10ns : tf £ 10ns 0V –VOD2 tPLH tPHL VOH R 1.5V OUTPUT 1.5V VOL LTC491 • F07 Figure 7. Receiver Propagation Delays 3V REB 1.5V f = 1MHz : tr £ 10ns : tf £ 10ns 1.5V 0V tZL tLZ 5V RVOL 1.5V OUTPUT NORMALLY LOW 0.5V VOH 0.5V R OUTPUT NORMALLY HIGH 1.5V 0V tZH tHZ LTC491 • F08 Figure 8. Receiver Enable and Disable Times 491fa 6

LTC491 APPLICATIOU S IU FORW ATIOU Typical Application outputs of the driver are accidently shorted to a power supply or low impedance source, up to 250mA can flow A typical connection of the LTC491 is shown in Figure 9. through the part. The thermal shutdown circuit disables Two twisted-pair wires connect up to 32 driver/receiver the driver outputs when the internal temperature reaches pairs for full duplex data transmission. There are no 150(cid:176) C and turns them back on when the temperature cools restrictions on where the chips are connected to the wires, to 130(cid:176) C. If the outputs of two or more LTC491 drivers are and it isn’t necessary to have the chips connected at the shorted directly, the driver outputs can not supply enough ends. However, the wires must be terminated only at the current to activate the thermal shutdown. Thus, the ther- ends with a resistor equal to their characteristic imped- mal shutdown circuit will not prevent contention faults ance, typically 120W . The input impedance of a receiver is when two drivers are active on the bus at the same time. typically 20kW to GND, or 0.6 unit RS-485 load, so in practice 50 to 60 transceivers can be connected to the same wires. The optional shields around the twisted pair help reduce unwanted noise, and are connected to GND at 12 one end. 2 120W RX RECEIVER DATA IN 3 11 The LTC491 can also be used as a line repeater as shown 4 in Figure 10. If the cable length is longer than 4000 feet, the LTC491 is inserted in the middle of the cable with the 10 receiver output connected back to the driver input. 5 120W DX DRIVER DATA OUT 9 Thermal Shutdown LTC491 LTC491 • F10 The LTC491 has a thermal shutdown feature which pro- tects the part from excessive power dissipation. If the Figure 10. Line Repeater 12 12 2 120W 120W 2 RX RECEIVER RECEIVER RX 3 11 11 3 4 4 10 10 5 120W 120W 5 DX DRIVER DRIVER DX 9 9 LTC491 9 10 11 12 LTC491 LTC491 RECEIVER DRIVER LTC491 • F09 5 4 3 2 DX RX Figure 9. Typical Connection 491fa 7

LTC491 APPLICATIOUS IUFORWATIOU Cables and Data Rate When using low loss cables, Figure 12 can be used as a guideline for choosing the maximum line length for a given The transmission line of choice for RS485 applications is data rate. With lower quality PVC cables, the dielectric loss a twisted pair. There are coaxial cables (twinaxial) made factor can be 1000 times worse. PVC twisted pairs have for this purpose that contain straight pairs, but these are terrible losses at high data rates (>100kBs), and greatly less flexible, more bulky, and more costly than twisted reduce the maximum cable length. At low data rates pairs. Many cable manufacturers offer a broad range of however, they are acceptable and much more economical. 120W cables designed for RS485 applications. Losses in a transmission line are a complex combination Cable Termination of DC conductor loss, AC losses (skin effect), leakage and The proper termination of the cable is very important. AC losses in the dielectric. In good polyethylene cables If the cable is not terminated with it’s characteristic such as the Belden 9841, the conductor losses and impedance, distorted waveforms will result. In severe dielectric losses are of the same order of magnitude, cases, distorted (false) data and nulls will occur. A quick leading to relatively low over all loss (Figure 11). look at the output of the driver will tell how well the cable is terminated. It is best to look at a driver connected to the 10 end of the cable, since this eliminates the possibility of getting reflections from two directions. Simply look at the driver output while transmitting square wave data. If the B) d cable is terminated properly, the waveform will look like a 0 ft ( square wave (Figure 13). 0 1 1.0 R PE If the cable is loaded excessively (47W ), the signal initially S S O sees the surge impedance of the cable and jumps to an L initial amplitude. The signal travels down the cable and is reflected back out of phase because of the mistermination. 0.1 0.1 1.0 10 100 FREQUENCY (MHZ) PROBE HERE LTC491 • F11 Figure 11. Attenuation vs Frequency for Belden 9481 Rt DX DRIVER RECEIVER RX 10k Rt = 120W H (ft) 1k T G N LE Rt = 47W E L B A100 C Rt = 470W 10 10k 100k 1M 2.5M 10M DATA RATE (bps) LTC491 • F13 LTC491 • F12 Figure 12. Cable Length vs Data Rate Figure 13. Termination Effects 491fa 8

LTC491 APPLICATIOUS IUFORWATIOU When the reflected signal returns to the driver, the ampli- Receiver Open-Circuit Fail-Safe tude will be lowered. The width of the pedestal is equal to Some data encoding schemes require that the output of twice the electrical length of the cable (about 1.5ns/foot). the receiver maintains a known state (usually a logic 1) If the cable is lightly loaded (470W ), the signal reflects in when the data is finished transmitting and all drivers on the phase and increases the amplitude at the driver output. An line are forced into three-state. The receiver of the LTC491 input frequency of 30kHz is adequate for tests out to 4000 has a fail-safe feature which guarantees the output to be in feet of cable. a logic 1 state when the receiver inputs are left floating (open-circuit). However, when the cable is terminated with AC Cable Termination 120W , the differential inputs to the receiver are shorted Cable termination resistors are necessary to prevent un- together, not left floating. Because the receiver has about wanted reflections, but they consume power. The typical 70mV of hysteresis, the receiver output will tend to main- differential output voltage of the driver is 2V when the tain the last data bit received, but this is not guaranteed. cable is terminated with two 120W resistors, causing The termination resistors are used to generate a DC bias 33mA of DC current to flow in the cable when no data is which forces the receiver output to a known state; in the being sent. This DC current is about 60 times greater than case of Figure 15, a logic 0. The first method consumes the supply current of the LTC491. One way to eliminate the about 208mW and the second about 8mW. The lowest unwanted current is by AC coupling the termination resis- power solution is to use an AC termination with a pull-up tors as shown in Figure 14. resistor. Simply swap the receiver inputs for data proto- The coupling capacitor must allow high-frequency energy cols ending in logic␣1. to flow to the termination, but block DC and low frequen- cies. The dividing line between high and low frequency 5V depends on the length of the cable. The coupling capacitor 110W 130W 130W 110W must pass frequencies above the point where the line represents an electrical one-tenth wavelength. The value RECEIVER RX of the coupling capacitor should therefore be set at 16.3pF per foot of cable length for 120W cables. With the coupling capacitors in place, power is consumed only on the signal 5V edges, and not when the driver output is idling at a 1 or 0 1.5k state. A 100nF capacitor is adequate for lines up to 4000 140W feet in length. Be aware that the power savings start to RECEIVER RX decrease once the data rate surpasses 1/(120W · C). 1.5kW 120W 100kW 5V C 120W C RECEIVER RX RECEIVER RX C = LINE LENGTH (ft) x 16.3pF LTC491 • F14 LTC491 • F15 Figure 14. AC Coupled Termination Figure 15. Forcing “O” When All Drivers are Off 491fa 9

LTC491 APPLICATIOUS IUFORWATIOU Fault Protection Y All of LTC’s RS485 products are protected against ESD 120W DRIVER transients up to 2kV using the human body model (100pF, 1.5kW ). However, some applications need more Z protection. The best protection method is to connect a bidirectional TransZorb® from each line side pin to ground (Figure 16). LTC491 • F16 A TransZorb is a silicon transient voltage suppressor that Figure 16. ESD Protection with TransZorbs has exceptional surge handling capabilities, fast response time, and low series resistance. They are available from required for your application (typically 12V). Also, don’t General Semiconductor Industries and come in a variety of forget to check how much the added parasitic capacitance breakdown voltages and prices. Be sure to pick a break- will load down the bus. down voltage higher than the common mode voltage TransZorb is a registered trademark of General Instruments, GSI PACKAGE DESCRIPTIOU N Package 14-Lead PDIP (Narrow .300 Inch) (Reference LTC DWG # 05-08-1510) .770* (19.558) MAX 14 13 12 11 10 9 8 .255 – .015* (6.477 – 0.381) 1 2 3 4 5 6 7 .300 – .325 .130 – .005 .045 – .065 (7.620 – 8.255) (3.302 – 0.127) (1.143 – 1.651) .020 (0.508) MIN .065 .008 – .015 (1.651) (0.203 – 0.381) TYP +.035 ( .325–.015 ) .120 .005 .018 – .003 8.255–+00..838891 (3M.0I4N8) (0M.1I2N5) (.21.0504) (0.457 – 0.076) BSC NOTE: INCHES 1. DIMENSIONS ARE N14 1002 MILLIMETERS *THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .010 INCH (0.254mm) 491fa 10

LTC491 PACKAGE DESCRIPTIOU S Package 14-Lead Plastic Small Outline (Narrow .150 Inch) (Reference LTC DWG # 05-08-1610) .337 – .344 .045 – .005 (8.560 – 8.738) .050 BSC NOTE 3 14 13 12 11 10 9 8 N N .245 .160 – .005 MIN .228 – .244 .150 – .157 (5.791 – 6.197) (3.810 – 3.988) NOTE 3 1 2 3 N/2 N/2 .030 – .005 TYP RECOMMENDED SOLDER PAD LAYOUT 1 2 3 4 5 6 7 .010 – .020 · 45° .053 – .069 (0.254 – 0.508) (1.346 – 1.752) .008 – .010 .004 – .010 (0.203 – 0.254) 0° – 8° TYP (0.101 – 0.254) .016 – .050 .014 – .019 .050 (0.406 – 1.270) (0.355 – 0.483) (1.270) TYP BSC NOTE: INCHES S14 0502 1. DIMENSIONS IN (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) 491fa Information furnished by Linear Technology Corporation is believed to be accurate and reliable. 11 However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.

LTC491 TYPICAL APPLICATIOU S RS232 Receiver RS232 to RS485 Level Transistor with Hysteresis R = 220k RS232 IN 5.6k RECEIVER RX Y 10k 120W 1/2 LTC491 RS232 IN DRIVER LTC491 • TA02 5.6k 1/2 LTC491 Z (cid:231)VY - VZ (cid:231) 19k HYSTERESIS = 10kW • — — — — » ———— R R LTC491 • TA03 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LTC486/LTC487 Low Power Quad RS485 Drivers 110m A Supply Current LTC488/LTC489 Low Power Quad RS485 Receivers 7mA 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 Transceiver 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), LTC491 Pin Compatible 491fa 12 Linear Technology Corporation LT/TP 0104 1K REV A • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 l FAX: (408) 434-0507 l www.linear.com ª LINEAR TECHNOLOGY CORPORATION 1992

Mouser Electronics Authorized Distributor Click to View Pricing, Inventory, Delivery & Lifecycle Information: A nalog Devices Inc.: LTC491IN LTC491IS#PBF LTC491IN#PBF LTC491CN#PBF LTC491IS#TRPBF LTC491IS#TR LTC491CN LTC491CS#TRPBF LTC491CS LTC491IS LTC491CS#TR LTC491CS#PBF