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New Selectable Data Rate RS485-Networking Transceiver from STMicroelectronics

The STR485LV is suitable for either 20Mbps or 250kbps data rates and connects to both 1.8V and 3.3V logic devices

STMicroelectronics have released the STR485LV 3.3V transceiver for RS485 applications. The STR485LV enhances design flexibility by providing an external pin to select 20Mbps or 250kbps communication and interfacing directly with low-voltage logic down to 1.8V.

The user-selectable data rate allows designers to order the same device for both speeds 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 ideal for a wide variety of scenarios, including telecom infrastructure, high-speed data links, or low-voltage microcontroller communications.

Click for Larger Image - New Selectable Data Rate RS485-Networking Transceiver from STMicroelectronics Designers have the flexibility to 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 permits up to 256 transceivers on the same bus in accordance with the RS485 specification.

Rich features for safety and robustness 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 ±8kV contact discharge and ±16kV air discharge without latch-up, exceeding IEC 61000-4-2 specifications, and are resistant to IEC61000-4-4 fast transient burst class-B.

Features of the STR485LV 3.3V RS485-Networking Transceiver

  • Half-duplex RS485 transceiver
  • 1.65 V to 3.6 V supply for data and enable signals
  • 3 V to 3.6 V supply for bus supply
  • High speed: up to 20 Mbps data rate
  • Low speed selected by SLR pin : 250 kbps
  • Up to 256 transceivers on the bus
  • Fail safe receiver (bus open, idle and shorted)
  • Thermal shutdown protection
  • Low quiescent current in shutdown mode
  • Extended temperature range : -40 °C to +105 °C

For more information on the STR485LV 3.3V RS485-Networking Transceiver, visit the ST Website at STMicroelectronics STR485LV product page

The company's Web site address is www.st.com.
[Reprinted with kind permission from STMicroelectronics - Release Date 3rd December, 2018]