Networking Transceiver Simplifies Designs, Saves Space


Simplifying design chores, saving space and costs, STMicroelectronics’ STR485LV 3.3V transceiver for RS485 applications provides an external pin to select 20 Mb/s or 250kb/s communication and interfacing directly with low-voltage logic down to 1.8V. The user-selectable data rate allows designers to specify the same device and thus simplify inventory management for RS485-networking applications, ranging from high-speed/short-range up to the maximum communication distance (4000 feet) depending on cable performance. It is suitable for a wide variety of applications including telecom infrastructure, high-speed data links, or low-voltage microcontroller communications.


Users can connect low-voltage logic devices from 1.8V to 3.3V directly, without needing level-shifting components, leveraging the 1.65-3.6V supply-voltage range for data and enable signals. By maintaining internal driver-output resistance above 96Ω up to +105°C, the STR485 allows up to 256 transceivers on the same bus in accordance with the RS485 specification.


Safety features include thermal shutdown to prevent bus contention or faults causing excessive power consumption, and a receiver failsafe mode that prevents errors if inputs are idle, shorted, or unconnected. The bus pins withstand over ±8-kV contact discharge and ±16-kV air discharge without latch-up, exceeding IEC 61000-4-2 specifications, and are resistant to IEC61000-4-4 fast transient burst class-B. 


Packaged as a 3mm x 3mm DFN10 featuring flow-through logic-to-bus pinning, the STR485 is available now, priced from $1.55 each/1,000. For deeper knowledge and enlightenment, download the STR485LV datasheet.