MAX485CSA

Part: MAX485 — Maxim Integrated Products

Type: RS-485/RS-422 Transceiver

Description: Low-power, half-duplex RS-485/RS-422 transceiver operating from a single 5V supply, capable of transmitting data up to 2.5Mbps, featuring a fail-safe receiver and drawing as little as 0.1μA in shutdown mode.

Operating Conditions:

• Supply voltage: 4.75–5.25 V
• Operating temperature: 0 to +70 °C
• Max data rate: 2.5 Mbps

Absolute Maximum Ratings:

• Max supply voltage: 12 V
• Max junction/storage temperature: -65°C to +160°C

Key Specs:

• Differential Driver Output (R = 27 Ω, RS-485): 1.5 V (min) to 5 V (max)
• Driver Common-Mode Output Voltage: 3 V (max)
• Receiver Differential Threshold Voltage: -0.2 V (min) to 0.2 V (max)
• Receiver Input Hysteresis: 70 mV (typ)
• Receiver Input Resistance: 12 kΩ (min)
• No-Load Supply Current (MAX485, DE=0V): 300 μA (typ), 500 μA (max)
• Supply Current in Shutdown (MAX481/483/487): 0.1 μA (typ), 10 μA (max)
• Driver Input to Output Propagation Delay (tPLH, tPHL): 10 ns (min), 60 ns (max)

Features:

• Low-power operation
• Half-duplex communication
• Unlimted slew-rate drivers for up to 2.5Mbps transmission
• Low-current shutdown mode (0.1μA)
• Short-circuit current limited drivers
• Thermal shutdown protection
• Fail-safe receiver input

Applications:

• Low-Power RS-485 Transceivers
• Low-Power RS-422 Transceivers
• Level Translators
• Transceivers for EMI-Sensitive Applications
• Industrial-Control Local Area Networks

Package:

• 8-Pin Plastic DIP
• 14-Pin Plastic DIP
• 8-Pin SO
• 14-Pin SO
• 8-Pin μMAX
• 8-Pin CERDIP
• 14-Pin CERDIP

The MAX481, MAX483, MAX485, MAX487-MAX491, and MAX1487 are low-power transceivers for RS-485 and RS422 communication. Each part contains one driver and one receiver. The MAX483, MAX487, MAX488, and MAX489 feature reduced slew-rate drivers that minimize EMI and reduce reflections caused by improperly terminated cables, thus allowing error-free data transmission up to 250kbps. The driver slew rates of the MAX481, MAX485, MAX490, MAX491, and MAX1487 are not limited, allowing them to transmit up to 2.5Mbps.

These transceivers draw between 120μA and 500μA of supply current when unloaded or fully loaded with disabled drivers. Additionally, the MAX481, MAX483, and MAX487 have a low-current shutdown mode in which they consume only 0.1μA. All parts operate from a single 5V supply.

Drivers are short-circuit current limited and are protected 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.

The MAX487 and MAX1487 feature quarter-unit-load receiver input impedance, allowing up to 128 MAX487/ MAX1487 transceivers on the bus. Full-duplex communications are obtained using the MAX488-MAX491, while the MAX481, MAX483, MAX485, MAX487, and MAX1487 are designed for half-duplex applications.

Low-Power RS-485 Transceivers Low-Power RS-422 Transceivers Level Translators Transceivers for EMI-Sensitive Applications Industrial-Control Local Area Networks

• ♦ For Fault-Tolerant Applications

MAX3430: ±80V Fault-Protected, Fail-Safe, 1/4 Unit Load, +3.3V, RS-485 Transceiver MAX3440E-MAX3444E: ±15kV ESD-Protected, ±60V Fault-Protected, 10Mbps, Fail-Safe, RS-485/J1708 Transceivers

• ♦ For Space-Constrained Applications MAX3460-MAX3464: +5V, Fail-Safe, 20Mbps, Profibus RS-485/RS-422 Transceivers MAX3362: +3.3V, High-Speed, RS-485/RS-422 Transceiver in a SOT23 Package MAX3280E-MAX3284E: ±15kV ESD-Protected, 52Mbps, +3V to +5.5V, SOT23, RS-485/RS-422, True Fail-Safe Receivers MAX3293/MAX3294/MAX3295: 20Mbps, +3.3V, SOT23, RS-855/RS-422 Transmitters
• ♦ For Multiple Transceiver Applications MAX3030E-MAX3033E: ±15kV ESD-Protected, +3.3V, Quad RS-422 Transmitters
• ♦ For Fail-Safe Applications MAX3080-MAX3089: Fail-Safe, High-Speed (10Mbps), Slew-Rate-Limited RS-485/RS-422 Transceivers
• ♦ For Low-Voltage Applications MAX3483E/MAX3485E/MAX3486E/MAX3488E/ MAX3490E/MAX3491E: +3.3V Powered, ±15kV ESD-Protected, 12Mbps, Slew-Rate-Limited, True RS-485/RS-422 Transceivers

Ordering Information appears at end of data sheet.

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Maxim Integrated Products 1

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.

Figure 1. MAX481/MAX483/MAX485/MAX487/MAX1487 Pin Configuration and Typical Operating Circuit

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Figure 2. MAX488/MAX490 Pin Configuration and Typical Operating Circuit

Figure 3. MAX489/MAX491 Pin Configuration and Typical Operating Circuit

(VCC = 5V ±5%, TA = TMIN to TMAX, unless otherwise noted.) (Notes 1, 2)

2

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• Control Input Voltage ( RE , DE)...................-0.5V to (V CC + 0.5V)

• Driver Input Voltage (DI).............................-0.5V to (V CC + 0.5V)

• Driver Output Voltage (A, B)...................................-8V to +12.5V

• Receiver Input Voltage (A, B).................................-8V to +12.5V

• Receiver Output Voltage (RO).....................-0.5V to (V CC +0.5V)

• Continuous Power Dissipation (T A = +70°C)

• 8-Pin Plastic DIP (derate 9.09mW/°C above +70°C) ....727mW

• 14-Pin Plastic DIP (derate 10.00mW/°C above +70°C) ..800mW

• 8-Pin SO (derate 5.88mW/°C above +70°C).................471mW

• 8-Pin μMAX (derate 4.1mW/°C above +70°C)..............830mW

• 8-Pin CERDIP (derate 8.00mW/°C above +70°C).........640mW

• 14-Pin CERDIP (derate 9.09mW/°C above +70°C).......727mW

• Operating Temperature Ranges

• MAX4_ C /MAX1487C A...............................0°C to +70°C

• MAX4_ E /MAX1487E A.............................-40°C to +85°C

• MAX4_ MJ/MAX1487MJA ...........................-55°C to +125°C

• Storage Temperature Range.............................-65°C to +160°C

• Lead Temperature (soldering, 10sec) .............................+300°C

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.

The MAX481, MAX483, MAX485, MAX487-MAX491, and MAX1487 transceivers are designed for bidirectional data communications on multipoint bus transmission lines.

Figure 19. MAX481/MAX485/MAX490/MAX491/MAX1487 System Differential Voltage at 110kHz Driving 4000ft of Cable

To minimize reflections, the line should be terminated at both ends in its characteristic impedance, and stub lengths off the main line should be kept as short as possible. The slew-rate-limited MAX483 and MAX487-MAX489 are more tolerant of imperfect termination.

Figure 20. MAX483, MAX487-MAX489 System Differential Voltage at 110kHz Driving 4000ft of Cable

Figure 19. MAX481/MAX485/MAX490/MAX491/MAX1487 System Differential Voltage at 110kHz Driving 4000ft of Cable

Figure 21. MAX481/MAX483/MAX485/MAX487/MAX1487 Typical Half-Duplex RS-485 Network

Figure 20. MAX483, MAX487-MAX489 System Differential Voltage at 110kHz Driving 4000ft of Cable

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Figure 22. MAX488-MAX491 Full-Duplex RS-485 Network

Figure 23. Line Repeater for MAX488-MAX491

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(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages .)

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