Intersil's ISL3179E is a ±15kV IEC61000 ESD Protected, 3.3V powered, single transceiver that meets both the RS-485 and RS-422 standards for balanced communication. This device has low bus currents (+220μA/-150μA), so it presents a “1/5 unit load” to the RS-485 bus. This allows up to 160 transceivers on the network without violating the RS-485 specification’s 32 unit load maximum, and without using repeaters. Receiver (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. Hot Plug circuitry ensures that the Tx and Rx outputs remain in a high impedance state while the power supply stabilizes.
The ISL3179E is a single‑chip RS‑485/RS‑422 transceiver offering IEC61000‑4‑2 ESD protection up to +16.5 kV, a 1/5 unit load that permits up to 160 devices on a bus, and full fail‑safe receiver behavior. It operates from a 3.3 V supply (±10% tolerance) and supports data rates up to 40 Mbps while consuming a low quiescent current of 4 mA.
Designed for industrial and process‑control networks, the device includes hot‑plug circuitry to keep Tx/Rx outputs high‑impedance during power‑up, and it is available in multiple plastic packages (SOIC, MSOP, DFN) with detailed mechanical drawings for PCB layout.
| ESD Protection | +15 kV IEC61000 on RS‑485 pins |
|---|---|
| Maximum Data Rate | 40 Mbps |
| Unit Load | 1/5 unit load, up to 160 devices |
| Supply Voltage | 3.3 V (±10% tolerance) |
| Operating Temperature | -40 °C to +125 °C |
| Quiescent Current | 4 mA max |
Up to 160 devices can share the bus because the ISL3179E presents a 1/5 unit load.