SP485R 1/10th Unit Load RS-485 Transceiver FEATURES Allows Over 400 Transceivers On A Transmission Line (1/10th Unit Load) High Impedance on Receiver Inputs (R = 150k typical) IN Half-Duplex Configuration Consistent With Industry Standard Pinout -7V to +12V Common Mode Input Voltage Range Low Power Consumption (250mW) Separate Driver and Receiver Enable DESCRIPTION The SP485R is a pin-to-pin equivalent to our existing SP485 product and offers a high receiver input impedance. The higher receiver input impedance allows for connecting over 400 transceivers on a single transmission line without degrading the RS-485 driver signal. The device is packaged in a 8-pin plastic DIP or 8-pin narrow SOIC. Figure 1. Typical Application Circuit SP485R 101 013020 1ABSOLUTE MAXIMUM RATINGS These are stress ratings only and functional operation Power Dissipation of the device at these ratings or any other above those 8-pin NSOIC.................................................1000mW indicated in the operation sections of the specifications ( = 62C/W) JA below is not implied. Exposure to absolute maximum 8-pin PDIP....................................................1000mW rating conditions for extended periods of time may ( = 62C/W) JA affect reliability. V .......................................................................+7V CC Storage Temperature.......................-65C to +150C ELECTRICAL CHARACTERISTICS Typically 25C V = +5V unless otherwise noted. CC PARAMETERS MIN. TYP. MAX. UNITS CONDITIONS LOGIC INPUTS V 0.8 Volts IL V 2.0 Volts IH LOGIC OUTPUTS V 0.4 Volts I = -3.2mA OL OUT V 2.4 Volts I = 1.0mA OH OUT RS-485 DRIVER DC Characteristics Open Circuit Voltage 6.0 Volts Differential Output Voltage 1.5 5.0 Volts R = 54, C = 50pF L L Balance +/-0.2 Volts V - V T T Common-Mode Output 3.0 Volts Output Current 28.0 mA R = 54 L Short Circuit Current +/-250 mA Terminated in -7V to +12V RS-485 DRIVER AC Characteristics Maximum Data Rate 5 Mbps R = 54, L Output Transition Time 30 ns Rise/fall time, 10% to 90% Propagation Delay, t 60 100 ns See Figures 4 & 6, R = 54, PLH DIFF C = C = 100pF L1 L2 Propagation Delay, t 60 100 ns See Figures 4 & 6, R = 54, PHL DIFF C = C = 100pF L1 L2 Driver Output Skew 5 15 ns see Figures 4 and 6, t = t - t SKEW DPHL DPLH RS-485 RECEIVER DC Characteristics Output Voltage Low, V 0.4 Volts OL Output Voltage High, V 2.4 Volts OH Tri-State Output Current +/-1 A 0.4V V 2.4V RE = Vcc OUT SP485R 101 013020 2