MAX3480A/MAX3480B 19-0453 Rev 0 1/96 Complete, Isolated, 3.3V RS-485/RS-422 Data Interface General Description Features The MAX3480A/MAX3480B are electrically isolated Isolated Data Interface to 1600V (1 minute) RMS RS-485/RS-422 data-communications interfaces. Slew-Rate-Limited Data Transmission (MAX3480B) Transceivers, optocouplers, and a transformer are all included in one low-cost, 28-pin DIP package. A single High-Speed, Isolated, 2.5Mbps RS-485 Interface +3.3V supply on the logic side powers both sides of the (MAX3480A) interface. -7V to +12V Common-Mode Input Voltage Range The MAX3480B features reduced-slew-rate drivers that with Respect to Isolated Ground minimize EMI and reduce reflections caused by improperly terminated cables, allowing error-free data Single +3.3V Supply transmission at data rates up to 250kbps. The Current Limiting and Thermal Shutdown for MAX3480As driver slew rate is not limited, allowing Driver Overload Protection transmission rates up to 2.5Mbps. Standard 28-Pin DIP Package These devices typically draw 180mA of quiescent sup- ply current. The MAX3480B provides a low-power shut- down mode in which it consumes only 0.2A. Drivers are short-circuit current limited and are protect- ed against excessive power dissipation by thermal shutdown circuitry that places the driver outputs into a high-impedance state. The receiver input has a fail-safe feature that guarantees a logic-high output if the input is open circuit. Pin Configuration The MAX3480A/MAX3480B typically withstand 1600V RMS (1 minute) or 2000V (1 second). Their isolated inputs RMS and outputs meet RS-485/RS-422 specifications. TOP VIEW MAX3480A/B Applications Isolated RS-485/RS-422 Data Interface V CC1 AC1 1 28 Transceivers for EMI-Sensitive Applications V AC2 CC2 2 27 Industrial-Control Local Area Networks D1 ISO V 3 26 CC1 Automatic Test Equipment B D2 4 25 HVAC/Building Control Networks ISO RO DRV GND1 5 24 MAX845 MAX485 FS 6 23 A MAX487 Ordering Information SD 7 22 ISO DI IN V 8 21 ISO DE IN CC3 DATA PART TEMP. RANGE PIN-PACKAGE RATE DI ISO COM1 9 20 (kbps) V 10 19 ISO DI DRV CC4 MAX3480ACPI 0C to +70C 28 Plastic DIP 2500 18 ISO V DE 11 CC2 MAX3480AEPI -40C to +85C 28 Plastic DIP 2500 GND2 17 ISO DE DRV MAX3480BCPI 0C to +70C 28 Plastic DIP 250 12 MAX3480BEPI -40C to +85C 28 Plastic DIP 250 RO 13 16 ISO COM2 V 15 ISO RO LED CC5 14 ISOLATION BARRIER DIP Maxim Integrated Products 1 For free samples & the latest literature: Complete, Isolated, 3.3V RS-485/RS-422 Data Interface ABSOLUTE MAXIMUM RATINGS With Respect to GND: LED Forward Current (DI, DE, ISO RO LED) ......................50mA Supply Voltage (V V V V ) .........-0.3V to +3.8V Continuous Power Dissipation (T = +70C) CC1, CC2, CC4, CC5 A Supply Voltage (V ) ..........................................-0.3V to +7V Plastic DIP (derate 9.09mW/C above +70C) ...............727mW CC3 Control Input Voltage (SD, FS) ................-0.3V to (V + 0.3V) Operating Temperature Ranges CC Receiver Output Voltage (RO).................-0.3V to (V + 0.3V) MAX3480 CPI......................................................0C to +70C CC With Respect to ISO COM: MAX3480 EPI ...................................................-40C to +85C Control Input Voltage (ISO DE ) .........-0.3V to (ISO V + 0.3V) Storage Temperature Range .............................-65C to +160C CC Driver Input Voltage (ISO DI ).........-0.3V to (ISO V + 0.3V) Lead Temperature (soldering, 10sec) .............................+300C CC Receiver Output Voltage (ISO RO )......-0.3V to (ISO V + 0.3V) CC Driver Output Voltage (A, B)................................-8V to +12.5V Receiver Input Voltage (A, B)..............................-8V to +12.5V 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. ELECTRICAL CHARACTERISTICS (V = V = V = V = V = 3.0V to 3.6V, FS = 0V, T = T to T , unless otherwise noted. Typical values are at CC CC1 CC2 CC4 CC5 A MIN MAX V = V = V = V = V = 3.3V and T = +25C.) (Notes 1, 2, 3) CC CC1 CC2 CC4 CC5 A PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Supply Voltage V 3.0 3.3 3.6 V S f FS = 0V 600 SWL Switch Frequency kHz f FS = V or open 900 SWH CC MAX3480A, R = 180 260 L DE = V or open R = 54 280 CC L Operating Supply Current I mA CC MAX3480B, R = 120 200 L DE = V or open R = 54 240 CC L Shutdown Supply Current (Note 3) I SD = V 0.2 A SHDN CC3 V High 2.4 FSH FS Input Threshold V V Low 0.8 FSL FS Input Pull-Up Current I FS low 50 A FSL FS Input Leakage Current I FS high 10 pA FSM Input High Voltage V V - 0.4 V DE , DI (Figure 1) IH CC Input Low Voltage V 0.4 V IL DE , DI (Figure 1) Isolation Resistance R T = +25C, V = 50V 100 10,000 M ISO A ISO DC Isolation Capacitance C T = +25C, V = 50V 10 pF ISO A ISO DC Differential Driver Output (no load) V 8 V OD1 R = 50 (RS-422) 2 Differential Driver Output (with load) V V OD2 R = 27 (RS-485), Figure 3 1.5 5 Change in Magnitude of Driver Differential 0.3 R = 27 or 50, Output Voltage for Complementary V V OD Figure 3 Common Mode 0.3 Output States Driver Common-Mode Output V R = 27 or 50, Figure 4 4 V OC 2 MAX3480A/MAX3480B