Renesas RAA78815x RS-485/422 transceivers

Renesas Electronics has introduced the RAA78815x family of 5 V differential transceivers with electrical fast transient (EFT) immunity of ±5000 V and ESD protection up to ±16,000 V, making the products useful for noise-sensitive industrial communication networks. The six full- and half-duplex ruggedised devices meet both the RS-485 and RS-422 communication standards and are suitable for a variety of industrial network, process control network, building automation, long-haul network and security camera network applications.

The devices build on Renesas’s current ISL315x 5V RS-485 transceiver family with additional immunity for EFT. EFT immunity is critical for devices operating in harsh industrial and automation environments, such as HVAC, factory and smart grid equipment, where devices are frequently turned on and off or added and disconnected from the system. In addition, the family delivers good differential output voltages, featuring 3.1 V into the RS-485-required 54Ω load.

The high-speed transceivers also feature bus leakage currents of maximum 125 μA, representing a true 1/8 unit load to the RS-485 bus. Developers can connect up to 512 transceivers on the same bus without using repeaters and without compromising the RS-485 network standard’s 32-unit load maximum. The transceivers should therefore be able to lower implementation and downtime costs, since a single network can support more nodes with lower likelihood of communications issues due to ESD and EFT overvoltage transients.