Features and Benefits
- Electronics industries alliance (EIA) RS-485/RS-422 compliant
- Data rate: 2.5 Mbps
- Half-duplex and full duplex options
- Reduced slew rates for low electromagnetic interference (EMI)
- True fail-safe receiver inputs
- 5 µA (maximum) supply current in shutdown mode
- Up to 256 transceivers on one bus
- Outputs high-Z when disabled or powered off
- −7 V to +12 V bus common-mode range
- Thermal shutdown and short-circuit protection
- Pin-compatible with the MAX308x
- Specified over the −40°C to +85°C temperature range
- Available in 8-lead SOIC, 8-lead LFCSP, and 8-lead MSOP
- Qualified for automotive applications
The ADM4850 / ADM4851 / ADM4852 / ADM4853 / ADM4854 / ADM4855 / ADM4856 / ADM4857 are differential line transceivers suitable for high speed, half-duplex and full duplex data communication on multipoint bus transmission lines. They are designed for balanced data transmission and comply with EIA Standards RS-485 and RS-422. The ADM4850 / ADM4851 / ADM4852 / ADM4853 are half-duplex transceivers that share differential lines and have separate enable inputs for the driver and receiver. The full duplex ADM4854 / ADM4855 / ADM4856 / ADM4857 transceivers have dedicated differential line driver outputs and receiver inputs.
The devices have a 1/8-unit load receiver input impedance, which allows up to 256 transceivers on one bus. Because only one driver must be enabled at any time, the output of a disabled or powered down driver is three-stated to avoid overloading the bus.
The receiver inputs have a true fail-safe feature, which ensures a logic high output level when the inputs are open or shorted.
This guarantees that the receiver outputs are in a known state before communication begins and when communication ends. The driver outputs are slew rate limited to reduce EMI and data errors caused by reflections from improperly terminated buses. Excessive power dissipation caused by bus contention or by output shorting is prevented with a thermal shutdown circuit.
The devices are fully specified over the commercial and industrial temperature ranges and are available in 8-lead SOIC (ADM4850 through ADM4857), 8-lead LFCSP (ADM4850 / ADM4852 / ADM4853), and 8-lead MSOP (ADM4850 only) packages.
- Low power RS-485 applications
- EMI sensitive systems
- DTE to DCE interfaces
- Industrial control
- Packet switching
- Local area networks
- Level translators
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-RS485FD8EBZ allows quick and easy evaluation of full-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) and receiver output (RO). Bus signals A, B, Y and Z (full-duplex bus) can be connected to a bus screw terminal block. Termination resistors are fitted across A and B, as well as Y and Z. These can be connected in half-duplex configuration (A to Y, B to Z), in order to evaluate the RS-485 driver. Footprints are provided for pull-up and pull-down (biasing resistors) on the receiver inputs in order to provide the option to evaluate an RS-485 receiver with this configuration.
Devices for evaluation on the board must be ordered separately.
Product Selection Guide (1)
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
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Pricing displayed is based on 1-piece. The USA list pricing shown is for budgetary use only, shown in United States dollars (FOB USA per unit), and is subject to change. International prices may vary due to local duties, taxes, fees and exchange rates.