Milpitas, Calif.Intersil Corp. has introduced its most rugged RS-485/RS-422 transceiver family yet. The ISL317XE is the first Intersil RS-485 devices to have an IEC61000 ESD rating, providing what it says is the highest ESD standard in the industry. As a result, it can provide extreme protection for its customers' products. At the same time, the ISL317XE family of 3.3-V RS-485/RS-422 transceivers support a data transmission rate of 20-Mbits/s.
The ISL317XE family covers all features and configurations associated with the RS-485 protocol. Data-rate options are offered to match the application speed. For low-speed applications, the family offers slew-rate-limited versions at 250-kbits/s: ISL3170E/71E/72E, and 500-kbits/s: ISL3173E/74E/75E. The ISL3176E/77E/78E operates up to 20-Mbits/s for high-speed applications.
Applications include factory automation, security networks, building environmental control systems, industrial/process control systems and automated utility meter reading systems.
IEC61000 ESD protection on the I/O pins and 7-kV HBM on all other pins for enhanced reliability during the assembly process in Intersil's ISL317XE family eliminates the need for external protection circuitry, according to Randy Pitts, marketing manager for Intersil's Interface products group. This is a first for Intersil RS-485.
In addition, the ISL317XE family of 3.3-V RS-485/RS-422 transceivers is housed in a tiny MSOP (mini small-outline package), which saves between 50% and 70% in board space compared with 8 and 14-lead SOIC transceivers, respectively. It is also the only full duplex offering in an MSOP package, according to Intersil. All package types are RoHS compliant.
"We believe the ongoing change from 5-V to 3.3-V supply voltages is permanent," Pitts said. "Our board space advantage over our competitors will become more important as those changes continue throughout the industry."
Single 3.3-V operation with 10% tolerance potentially eliminates the need for a 5-V supply. It also lowers the cost of the power supply design or provides more margin for existing designs.
The ISL317XE family of 3.3-V RS-485/RS-422 transceivers has additional features that add value to RS-485 bus designs. They include full fail-safe receivers and hot-plug circuitry.
The ISL317XE family consists of one-eighth fractional-unit load devices that allow up to 256 transceivers on the network without repeaters and without violating the RS-485 specification. Very low bus current of +125µA/-75µA present a true one-eighth unit load to the RS-485 bus. Tx outputs and Rx inputs maintain this load even when the voltages exceed the supply voltages by as much as -7-V and +9-V (i.e. from -7-V to +12-V.
Rx inputs feature a full fail-safe design, which ensures a logic high Rx output if Rx inputs are floating, shorted, or terminated but undriven. The hot plug circuitry ensures that the Tx and Rx outputs remain tri-state during power up/power down. Driver outputs are short-circuit protected, even for voltages exceeding the power supply voltage. Also, on-chip thermal shutdown circuitry disables the Tx outputs to prevent damage, if power dissipation becomes excessive.
The ISL317XE family is available now in 8-lead MSOP packages, 8-lead SOIC packages, 10-lead MSOP packages and 14-lead SOIC packages with prices starting at $1.68 in 1,000-unit quantities.
More information on the ISL317XE family is available at www.intersil.com/products/partsearch.asp?txtprodnr=isl317.
Intersil Corp., 1-408-432-8888, www.intersil.com