LTC1487 Ultra-Low Power RS485 with Low EMI, Shutdown and High Input Impedance DESCRIPTIO EA U F T RES n High Input Impedance: Up to 256 Transceivers The LTC 1487 is an ultra-low power differential line trans- on the Bus ceiver designed with high impedance inputs allowing up to n Low Power: I = 120m A Max with Driver Disabled 256 transceivers to share a single bus. It meets the CC n I = 200m A Max with Driver Enabled, No Load requirements of RS485 and RS422. The LTC1487 features CC n 1m A Quiescent Current in Shutdown Mode output drivers with controlled slew rate, decreasing the n Controlled Slew Rate Driver for Reduced EMI EMI radiated from the RS485 lines, and improving signal n Single 5V Supply fidelity with misterminated lines. The CMOS design offers n ESD Protection to 10kV On Receiver Inputs and significant power savings without sacrificing ruggedness Driver outputs against overload or ESD damage. Typical quiescent cur- n 7V to 12V Common-Mode Range Permits 7V rent is only 80m A while operating and 1m A in shutdown. Ground Difference Between Devices on the Data Line The driver and receiver feature three-state outputs, with n Thermal Shutdown Protection the driver outputs maintaining high impedance over the n Power Up/Down Glitch-Free Driver Outputs Permit entire common-mode range. Excessive power dissipation Live Insertion or Removal of Transceiver caused by bus contention or faults is prevented by a n Driver Maintains High Impedance in Three-State thermal shutdown circuit which forces the driver outputs or with the Power Off into a high impedance state. The receiver has a fail-safe n Pin Compatible with the LTC485 feature which guarantees a high output state when the inputs are left open. I/O pins are protected against multiple ESD strikes of over 10kV using the Human Body Model. APPLICATI S The LTC1487 is fully specified over the commercial tem- n Battery-Powered RS485/RS422 Applications perature range and is available in 8-pin DIP and SO n Low Power RS485/RS422 Transceiver packages. n Level Translator , LTC and LT are registered trademarks of Linear Technology Corporation. TYPICAL APPLICATI LTC1487 LTC1487 1 1 RO R R RO 2000 FEET OF TWISTED-PAIR WIRE 2 2 DI RE RE 3 3 7 7 DE DE 4 4 DI D 120W 120W D DI A 6 6 B 330W 4.7nF RO EQUIVALENT LOAD OF 256 LTC1487 TA01 LTC1487 TRANSCEIVERS LTC1487 TA02 sn1487 1487fs 1 RECEIVER INPUT UO UO ULTC1487 ABSOLUTEXAI U RATI GS PACKAGE/ORDER I FOR ATIO (Note 1) Supply Voltage (V ) .............................................. 12V ORDER PART CC TOP VIEW NUMBER Control Input Voltage..................... 0.5V to V + 0.5V CC RO 1 V 8 Driver Input Voltage....................... 0.5V to V + 0.5V CC CC R LTC1487CN8 RE 2 7 B Driver Output Voltage ........................................... 14V LTC1487CS8 DE 3 6 A Receiver Input Voltage.......................................... 14V D DI 4 5 GND Receiver Output Voltage ................ 0.5V to V + 0.5V CC Operating Temperature Range ............. 0 C T 70 C S8 PART MARKING N8 PACKAGE S8 PACKAGE A 8-LEAD PDIP 8-LEAD PLASTIC SO Storage Temperature Range ................ 65 C to 150 C 1487 Lead Temperature (Soldering, 10 sec)................. 300 C T = 125 C, q = 130 C/ W (N8) JMAX JA T = 125 C, q = 150 C/ W (S8) JMAX JA Consult factory for Industrial and Military grade parts. 0 C T 70 C, V = 5V (Notes 2, 3) unless otherwise noted. ELECTRICAL CHARACTERISTICS A CC SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS V Differential Driver Output Voltage (Unloaded) I = 0 l 5V OD1 O V Differential Driver Output Voltage (with Load) R = 50W (RS422) l 2.0 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 R = 27W or R = 50W , Figure 1 l 3V OC D V Change in Magnitude of Driver Common-Mode R = 27W or R = 50W , Figure 1 l 0.2 V OC 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 2 m A IN1 I Input Current (A, B) DE = 0, V = 0V or 5.25V, V = 12V l 0.30 mA IN2 CC IN DE = 0, V = 0V or 5.25V, V = 7V l 0.15 mA CC 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 45 mV TH CM V Receiver Output High Voltage I = 4mA, V = 200mV l 3.5 V OH O ID V Receiver Output Low Voltage I = 4mA, V = 200mV l 0.4 V OL O ID I Three-State (High Impedance) Output V = Max, 0.4V V 2.4V l 1 m A OZR CC O Current at Receiver R Receiver Input Resistance 7V V 12V l 70 96 kW IN CM I Supply Current No Load, Output Enabled l 120 200 m A CC No Load, Output Disabled l 80 120 m A I Supply Current in Shutdown Mode DE = 0V, RE = V 110 m A SHDN CC I Driver Short-Circuit Current, V = HIGH 7V V 12V l 35 250 mA OSD1 OUT O I Driver Short-Circuit Current, V = LOW 7V V 12V l 35 250 mA OSD2 OUT O I Receiver Short-Circuit Current 0V V V l785mA OSR O CC sn1487 1487fs 2 U WU U W W W