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Isolated RS-485
NVE offers a broad line of single-chip isolated RS-485 transceivers. IsoLoop logic isolators can also be used as part of multi-chip designs to isolate signals using particular non-isolated transceivers.

Illustrative circuits:
RS-485 Repeater Using IL610

Recommended application bulletins:
  AB-5: Isolated RS-485 and RS-422 (.pdf)
Dramatically reduce chip count and board area with IL400- and IL3000-Series single-chip isolated transceivers.
 
AB-6: RS-485 Systems (.pdf)
Practical tips and rules of thumb for making RS-485 systems work.
 
AB-10: Differential Line Receivers Using IL600-Series Isolators (.pdf)
The unique passive inputs of the IL600-Series Isolators are ideal for direct connection to differential networks such as RS-485 and RS-422. This document shows how to save components and reduce cost.

 RS-485 single-chip transceiver selector guide
Single-Chip RS-485/PROFIBUS Isolated Transceivers



NVE’s single-chip isolated RS-485 transceivers include digital- and passive-input versions, fractional-load versions, and PROFIBUS-compliant versions. Termination resistors can be added to maximize speed and transmission length. Fail-safe resistors guarantee a known state on a terminated bus with no active transceivers. NVE transceivers are available with data rates are up to 40 Mbps. Parts are available in 0.3" and 0.15" 16-pin SOIC packages.

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Single-Chip Passive-Input RS-485 Isolated Transceivers



NVE’s unique passive-input isolated transceivers have current-mode inputs for maximum flexibility. A typical circuit is shown above.

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Single-Component RS-485 Receiver Using IL610

An IL610 can be used as a simple isolated RS-485 receiver. No external resistors are required, and cabling is greatly simplified by eliminating the need to power the input side of the receiving board. The circuit is failsafe because the IL610 is guaranteed to switch to the high state when the coil input current is less than 500 µA. No current-limiting resistor is needed for a single receiver because it will draw less current than the driver maximum. There is also no need for line termination resistors in most IL610 line receiver applications below a data rate of about 10 Mbps because the IL610 coil resistance of approximately 70 Ohms is close to the characteristic impedance of most cables.

The IL610 provides 2.5 kVrms isolation (one minute), and 20 kV/µs transient immunity. The IL610-1 is a unique MSOP isolator for space-critical boards.

For more information on using IL600-Series Isolators as differential receivers, see Application Bulletin No. 10 (.pdf).

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RS-485 Repeater Using IL610

Simple, low cost, isolated repeater systems can be made with an RS-485 transceiver in drive mode and an IL610. Repeaters can extend the useful cable length and node count indefinitely, provided the network controller can tolerate the additional propagation delays.

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Isolated Fractional Load RS-485 Using IL614

NVE offers a broad line of single-chip isolated RS-485 transceivers, but the unique IL614 three-channel isolator can also be used as part of a multi-chip design with non-isolated transceivers. The IL614 provides 2.5 kVrms isolation (1 minute) and 20 kV/µs transient immunity. The IL614-3 is in a narrow-body (0.15"-wide) package when board space is critical.

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Isolated RS-485 Using IL710 and IL711

IL700 high-speed digital signal isolators can be used as part of multi-chip designs using non-isolated RS-485 transceivers. Circuits can be configured with three IL710s (circuit above) or one IL710 and one IL711 (circuit below). The IL710 and IL711 provide 2.5 kVrms isolation (1 minute) and 30 kV/µs typical common-mode transient immunity. The IL710-1 and IL711-1 are unique MSOP one- and two-channel isolators to minimize board space.

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