LTC1685 52Mbps, Precision Delay, RS485 Fail-Safe Transceiver DESCRIPTIO FEATURES n Precision Propagation Delay Over Temperature: The LTC 1685 is a high speed, precision delay RS485 Receiver/Driver: 18.5ns 3.5ns transceiver that can operate at data rates as high as 52Mbps. n High Data Rate: 52Mbps The device also meets the requirements of RS422. n Low t /t Skew: PLH PHL A unique architecture provides very stable propagation Receiver/Driver: 500ps Typ delays and low skew over a wide common mode and n 7V to 12V RS485 Input Common Mode Range ambient temperature range. n Guaranteed Fail-Safe Receiver Operation Over the The driver and receiver feature three-state outputs, with Entire Common Mode Range n disabled driver outputs maintaining high impedance over High Receiver Input Resistance: 22k, Even When the entire common mode range. A short circuit feature Unpowered n detects shorted outputs and substantially reduces driver Short-Circuit Protected n output current. A similar feature also protects the receiver Thermal Shutdown Protected n output from short circuits. Thermal shutdown circuitry Driver Maintains High Impedance in Three-State or protects from excessive power dissipation. with Power Off n Single 5V Supply The receiver has a fail-safe feature that guarantees a high n Pin Compatible with LTC485 output state when the inputs are shorted or are left floating. n 45dB CMRR at 26MHz The LTC1685 RS485 transceiver guarantees receiver fail- U safe operation over the entire common mode range (7V APPLICATIO S to 12V). Input resistance will remain 22k when the device is unpowered or disabled. n High Speed RS485/RS422 Transceivers n Level Translator The LTC1685 operates from a single 5V supply and draws n Backplane Transceiver only 7mA of supply current. n STS-1/OC-1 Data Transceiver , LTC and LT are registered trademarks of Linear Technology Corporation. n Fast-20, Fast-40 SCSI Transceivers TYPICAL APPLICATION 10Mbps Data Pulse 400ft Category 5 UTP RO1 V CC1 R RE1 DRIVER INPUT 2V/DIV Rt CABLE DELAY DE1 D DI1 GND1 RECEIVER 1V/DIV INPUT Rt RO2 V CC2 R RE2 RECEIVER 5V/DIV OUTPUT DE2 DI2 D GND2 100ns/DIV 1685 TA01 1685 TA02 1 U ULTC1685 O ABS LUTEXAI U RATI GS PACKAGE/ORDER I FOR ATIO (Note 1) Supply Voltage (V ) .............................................. 10V DD TOP VIEW ORDER PART Control Input Currents .................... 100mA to 100mA NUMBER RO 1 8 V Control Input Voltages .................. 0.5V to V + 0.5V DD DD R RE 2 B 7 Driver Input Voltages .................... 0.5V to V + 0.5V LTC1685CS8 DD DE 3 6 A Driver Output Voltages .................................. +12V/7V LTC1685IS8 DI D GND 4 5 Receiver Input Voltages ................................. +12V/7V S8 PART MARKING Receiver Output Voltages ............. 0.5V to V + 0.5V DD S8 PACKAGE 8-LEAD PLASTIC SO Receiver Input Differential ...................................... 10V 1685 T = 125 C, q = 150 C/ W Short-Circuit Duration (Driver V : 7V to 10V, JMAX JA OUT 1685I Receiver V : 0V to V ) ............................... Indefinite OUT DD Consult factory for Military grade parts. Operating Temperature Range LTC1685C ............................................... 0 C to 70 C LTC1685I............................................. 40 C to 85 C Storage Temperature Range ................ 65 C to 150 C Lead Temperature (Soldering, 10 sec)................. 300 C DC ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T = 25 C. V = 5V 5%, unless otherwise noted. (Notes 2, 3) A DD SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS V Differential Driver Output (Unloaded) I = 0 l V V OD1 OUT DD V Differential Driver Output (With Load) R = 50W (RS422) 2 V OD2 R = 27W (RS485), Figure 1 l 1.5 V V DD D V Change in Magnitude of Driver Differential R = 27W or 50W , Figure 1 l 0.2 V OD Output Voltage for Complementary Output States V Driver Common Mode Output Voltage R = 27W or 50W , V = 5V, Figure 1 l 23 V OC DD V Change in Magnitude of Driver Common R = 27W or 50W , Figure 1 l 0.2 V OC Mode Output Voltage for Complementary Output States V Input High Voltage DE, DI, RE l2V IH V Input Low Voltage DE, DI, RE l 0.8 V IL I Input Current DE, DI, RE l 1 1 m A IN1 I Input Current (A, B) V , V = 12V, DE = 0, V = 0V or 5.25V l 500 m A IN2 A B DD V , V = 7V, DE = 0, V = 0V or 5.25V l 500 m A A B DD V Differential Input Threshold Voltage 7V V 12V l 0.3 0.3 V TH CM for Receiver D V Receiver Input Hysteresis V = 0V 25 mV TH CM V Receiver Output High Voltage I = 4mA, V = 300mV l 3.5 4.8 V OH OUT ID V Receiver Output Low Voltage I = 4mA, V = 300mV l 0.4 V OL OUT ID I Three-State (High Impedance) Output 0.4V V 2.4V l 1 1 m A OZR OUT Current at Receiver I Supply Current No Load, Pins 2, 3, 4 = 0V or V l 712 mA DD DD I Driver Short-Circuit Current, V = HIGH V = 7V or 10V (Note 5) l 20 mA OSD1 OUT OUT 2 D U WU U W W W