TI's new RS-485 transceivers provide optimum AC performance

Texas Instruments Inc. (TI) recently introduced six full-featured, full-duplex RS-485 transceivers that promise to conserve power, provide optimum AC performance for key operating speeds, and allow up to 256 devices on a single RS-485 bus.

With an electrostatic discharge (ESD) protection in excess of 15kV (human body model), these new products provide a robust interface for both RS-485 and RS-422 applications, such as industrial and building automation, point-of-sale terminals and networks, data terminal equipment/data communications equipment interfaces, and utility meters. The SN65HVD33/34/35 and SN65HVD53/54/55 are differential line drivers and receivers, with separate input and output pins for full-duplex (4-wire) bus communication designs. These transceivers are designed for interoperation with ANSI TIA/EIA-485A, TIA/EIA-422-B, ITU-T V.11 and ISO 8482:1993 standard-compliant devices.

According to the press release, all of the devices provide key features and options to give designers the flexibility to maximize their system performance, such as slew rate-controlled outputs to avoid unwanted reflections, and higher-accuracy data transmission for signaling rates of 1-, 5- and 25Mbps. The families also provide a 1/8-unit load option, which allows for up to 256 nodes on the bus. Power supply options include 3.3V operation for the HVD3x family, and 5V operation for the HVD5x family. When in the low-current standby mode, the HVD3x supply current typically drops to 22nA. In addition, the HVD5x family provides strong bus drivers with differential output voltages well above the RS-485/RS-422 requirements. TI explained that this provides signal margin for applications with interconnection losses or noise immunity concerns.

The SN65HVD3x/5x devices are offered in a 14-pin SOIC package, and are priced at $1.85 for the HVD3x devices and $1.75 for the HVD5x devices in 1,000-unit quantities.