RS-485/422 transceivers claim highest EFT immunity

Click for a larger image. (Source: Renesas Electronics)

Targeting noise-sensitive industrial communication networks, Renesas Electronics Corp. released the RAA78815x family of 5-V differential RS-485/422 transceivers with industry-leading ±5 kV electrical fast transient (EFT) immunity and ESD protection up to 16.5 kV. The six full- and half-duplex ruggedized devices meet both the RS-485 and RS-422 communication standards and are suited for a variety of industrial network, process control network, building automation, long-haul network, and security camera network applications.

Building on Renesas’ current ISL315x 5-V RS-485 transceiver family with additional immunity for EFT, the RAA78815x family delivers “exceptional” differential output voltages, featuring 3.1 V into the RS-485-required 54 Ω 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, said Renesas.

Other key specs include a low 125 μA bus current, 550 μA supply current, and 70 nA shutdown current. The family supports multiple data rates in full- (RAA788150, RAA788153, and RAA788156) and half-duplex modes (RAA788152, RAA788155, and RAA788158).

Typical operating circuits of half-duplex and full-duplex transceivers. Click for a larger image. (Source: Renesas Electronics)

Renesas said 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. These transceiver family improvements can lower implementation and downtime costs, since a single network can support more nodes with a lower likelihood of communications issues due to ESD and EFT overvoltage transients, said the company.

The RAA78815x RS-485/422 transceivers are available now in 3 × 5 mm MSOP and 6 × 8.6 mm SOIC packages with pin counts ranging from 8 to 14. An evaluation board for the new transceiver family is also available.