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Low-leakage quad RS-422 transmitters deliver maximum ESD protection in small packages

2nd June 2009

ES Admin

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Intersil has developed a series of small-footprint, quad 16.5kV ESD-protected RS-422 transmitters. These innovative devices feature wide supply-voltage operating ranges for motor control applications, process control networks, telecommunications products and factory automation systems.

The ISL32179E, ISL32272E and ISL32274E withstand ESD during assembly and while in use, featuring +/- 16.5 kV ESD protection that meets HBM and IEC61000-4-2 standards on transmitter outputs. All of the transmitters also feature power-saving low-output leakage currents, at just ± 20uA. Designed to operate from either 3.3V or 5V and at temperatures between -40 to 125 degrees C, the new transmitters can replace existing RS-422 transmitters that are restricted to 5V supply voltages or that operate in limited temperature ranges.

The ISL32179E, ISL32272E and ISL32274E are superior choices for designs using the RS-422 communication interface, providing maximum protection from the harshest ESD events during assembly and use. Data rates reach 32 Megabits/second, and quiescent current is a low 0.8mA, maximum. Slew rate-limited versions are also offered, so low data rate applications can minimize EMI and transmission line reflections. Shutdown supply current is as low as 60uA on the QFN package versions. Driver (Tx) outputs are tri-statable, and incorporate a hot-plug feature to keep them disabled during power-up and power-down.

Industry-standard versions are available in TSSOP or widely used NSOIC packages, while the ISL32179E is offered in tiny 4 x 4mm QFN packages that are 50 percent smaller than the TSSOPs, providing significant board-space savings. The ISL32179E also features data-rate and enable options, offering maximum design versatility. Multiple enable pins allow the user to choose active high or low group enables (EN or EN#), paired-enables (EN12 and EN34) or individual channel enables, available on the ISL32179E, and speed select pins allow the user to select data rates from 460kbps to 32Mbps, also available only on the ISL32179E. The ultra-small QFN package incorporates a VL pin to adjust the logic-pin input thresholds, eliminating the need for extended voltage level translator ICs in most designs.

The ISL32272E and ISL32274E are available now in 16-lead TSSOP and 16-lead SOIC packages. The ISL32179E comes in a 24-lead QFN package.