Features and Benefits
- Meets EIA RS-485 Standard
- 5 Mbps Data Rate
- Single 5 V Supply
- –7 V to +12 V Bus Common-Mode Range
- High Speed, Low Power BiCMOS
- Thermal Shutdown Protection
- Short-Circuit Protection
- Driver Propagation Delay: 10 ns
- Receiver Propagation Delay: 15 ns
- High Z Outputs with Power Off
- Superior Upgrade for LTC485
Product DetailsThe ADM485 is a differential line transceiver suitable for high speed bidirectional data communication on multipoint bus transmission lines. It is designed for balanced data transmission and complies with both EIA Standards RS-485 and RS-422. The part contains a differential line driver and a differential line receiver. Both the driver and the receiver may be enabled independently. When disabled, the outputs are tristated.
The ADM485 operates from a single +5 V power supply. Excessive power dissipation caused by bus contention or by output shorting is prevented by a thermal shutdown circuit. This feature forces the driver output into a high impedance state if during fault conditions a significant temperature increase is detected in the internal driver circuitry.
Up to 32 transceivers may be connected simultaneously on a bus, but only one driver should be enabled at any time. It is important, therefore, that the remaining disabled drivers do not load the bus. To ensure this, the ADM485 driver features high output impedance when disabled and also when powered down.
This minimizes the loading effect when the transceiver is not being utilized. The high impedance driver output is maintained over the entire common-mode voltage range form -7V to +12 V.
The receiver contains a fail safe feature which results in a logic high output state if the inputs are unconnected (floating).
The ADM485 is fabricated on BiCMOS, an advanced mixed technology process combining low power CMOS with fast switching bipolar technology. All inputs and outputs contain protection against EDS; all diver outputs feature high source and sink current capability. An epitaxial layer is used to guard against latch-up.
The ADM485 features extremely fast switching speeds. Minimal driver propagation delays permit transmission at data rates up to 5 Mbits/s while low skew minimizes EMI interference.
The part is fully specified over the commercial and industrial temperature range and is available in an 8-pin DIL/SOIC packages.
Product Lifecycle Production
At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.
Evaluation Kits (1)
The EVAL-RS485HDEBZ allows quick and easy evaluation of half-duplex RS-485 transceivers with standard 8-lead SOIC footprints. The evaluation board allows interfacing via screw terminal block to digital I/O for driver input (DI), receiver output (RO), driver enable (DE) and receiver output (RO). Bus signals A and B (half-duplex bus) can be connected to a bus screw terminal block. One or two termination resistors can be connected to A and B via jumper settings, in order to evaluation the half-duplex RS-485 driver and receiver. Footprints are provided for pull-up and pull-down (biasing resistors) on the bus.
Devices for evaluation on the board must be ordered separately.
Tools & Simulations
Product Selection Guide (1)
Solutions Bulletins & Brochures (2)
ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal.
Sample & Buy
The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.