MAX3471 19-0497 Rev 0 2/98 1.6A, RS-485/RS-422, Half-Duplex, Differential Transceiver for Battery-Powered Systems General Description Features The MAX3471 half-duplex transceiver is intended for 1.6A Supply Current with Receiver Enabled lithium battery-powered RS-485/RS-422 applications. It +2.5V to +5.5V Single-Supply Operation draws only 1.6A (typical) supply current from a 3.6V supply with the receiver enabled and the driver dis- True Fail-Safe Receiver Input abled. Its wide 2.5V to 5.5V supply voltage guarantees Available in MAX Package operation over the lifetime of a lithium battery. This device features true fail-safe operation that guar- 1/8-Unit-Load Receiver Input antees a logic-high receiver output when the receiver -7V to +10V Common-Mode Input Voltage Range inputs are open or shorted. This means that the receiv- er output will be a logic high if all transmitters on a ter- minated bus are disabled (high impedance). The Ordering Information MAX3471 has a 1/8-unit load input resistance. When driver outputs are enabled and pulled above V or CC PART TEMP. RANGE PIN-PACKAGE below GND, internal circuitry prevents battery back- MAX3471CUA 0C to +70C 8 MAX charging. MAX3471EUA -40C to +85C 8 MAX The MAX3471 is available in an 8-pin MAX package. Applications Pin Configuration Remote Meter Reading TOP VIEW Battery-Powered Differential Communications Level Translators RO 1 8 V CC RE 2 7 B MAX3471 DE 3 6 A DI 4 5 GND MAX Typical Application Circuit V CC V V CC CC 0.1F B B DI DE D D A A DE DI BA BA RO R R RO RE RE V V GND GND CC CC GND R R D D REMOTE UNIT CENTRAL UNIT DI DE RO RE DI DE RO RE MAX3471 REMOTE UNIT REMOTE UNIT TYPICAL HALF-DUPLEX RS-485 NETWORK Maxim Integrated Products 1 For free samples & the latest literature: 1.6A, RS-485/RS-422, Half-Duplex, Differential Transceiver for Battery-Powered Systems ABSOLUTE MAXIMUM RATINGS (Note 1) Supply Voltage (V ) ..............................................................7V Operating Temperature Ranges CC Control Input Voltage (RE, DE)...................-0.3V to (V + 0.3V) MAX3471CUA.....................................................0C to +70C CC Driver Input Voltage (DI).............................-0.3V to (V + 0.3V) MAX3471EUA ..................................................-40C to +85C CC Driver Output/Receiver Input Voltage (A, B).....................10.5V Storage Temperature Range .............................-65C to +160C Receiver Output Voltage (RO)....................-0.3V to (V + 0.3V) Lead Temperature (soldering, 10sec) .............................+300C CC Continuous Power Dissipation MAX (derate 4.5mW/C above +70C) ......................362mW Note 1: All currents into the device are positive all currents out of the device are negative. All voltages are referred to device ground unless otherwise noted. Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. DC ELECTRICAL CHARACTERISTICS (V = +2.5V to +5.5V, T = T to T , unless otherwise noted. Typical values are at V = +3.6V and T = +25C.) (Note 1) A MIN MAX CC A CC PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Differential Driver Output (no load) V Figure 1 (R = open) V V OD1 CC R = 750 (RS-422) 1.5 3.28 R = 27 (RS-485) 0.2 0.83 Differential Driver Output V Figure 1 V OD2 (with load) R = 27W (RS-485), 1.5 V = 5V, T = +25C CC A Change in Magnitude of Differential Output Voltage V Figure 1, R = 750 or 27 0.2 V OD (Note 2) Driver Common-Mode Output V Figure 1, R = 750 or 27 0.6 x V V OC CC Voltage Change in Magnitude of V Figure 1, R = 750 or 27 0.2 V OC Common-Mode Voltage (Note 2) Input High Voltage V DE, DI, RE 0.7 x V V IH CC Input Low Voltage V DE, DI, RE 0.3 x V V IL CC DI Input Hysteresis V 100 mV HYS Input Current I DE, DI, RE 0.001 1 A IN1 V = 10V 0.105 Input Current (A and B), DE = GND, IN I mA IN2 Half Duplex V = GND or 5.5V CC V = -7V -0.075 IN V 3.6V -60 60 CC Driver Short-Circuit Output I -7V V 10V mA OSD OUT Current (Note 3) V 5.5V -130 130 CC Receiver Differential Threshold V -7V V 10V -450 -250 -50 mV TH CM Voltage Receiver Input Hysteresis V V = 0 32 mV TH CM Receiver Output High Voltage V I = -0.8mA, V = -50mV V - 0.4 V OH O ID CC Receiver Output Low Voltage V I = 2.2mA, V = -450mV 0.4 V OL O ID Three-State Current at Receiver I 0 V V 1 A OZR O CC Output Receiver Input Resistance R -7V V 10V 96 kW CM IN 2 MAX3471