Features and Benefits
- Low Power: ICC = 300µA Typical
- Designed for RS485 or RS422 Applications
- Single 5V Supply
- -7V to 12V Bus Common Mode Range Permits ±7V Ground Difference Between Devices on the Bus
- Thermal Shutdown Protection
- Power-Up/Down Glitch-Free Driver Outputs Permit Live Insertion or Removal of Package
- Driver Maintains High Impedance in Three-State or with the Power Off
- Combined Impedance of a Driver Output and Receiver Allows up to 32 Transceivers on the Bus
- 70mV Typical Input Hysteresis
- 28ns Typical Driver Propagation Delays with 5ns Skew for 2.5MB Operation
- Pin Compatible with the SN75180
- Available in 14-Lead PDIP and SO Packages
The LTC491 is a low power differential bus/line transceiver designed for multipoint data transmission standard RS485 applications with extended common mode range (12V to –7V). It also meets the requirements of RS422.
The CMOS design offers significant power savings over its bipolar counterpart without sacrificing ruggedness against overload or ESD damage.
The driver and receiver feature three-state outputs, with the driver outputs maintaining high impedance over the entire common mode range. Excessive power dissipation caused by bus contention or faults is prevented by a thermal shutdown circuit which forces the driver outputs into a high impedance state.
The receiver has a fail safe feature which guarantees a high output state when the inputs are left open.
Both AC and DC specifications are guaranteed from 0°C to 70°C and 4.75V to 5.25V supply voltage range.
- Low Power RS485/RS422 Transceiver
- Level Translator
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-RS485FDEBZ allows quick and easy evaluation of full-duplex RS-485 transceivers with standard 14-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, 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
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.