ISO1211 Isolated 24-V Digital Input Receiver

The ISO1211 is an isolated 24-V to 60-V digital input receiver, compliant to IEC 61131-2 Type 1, 2, and 3 characteristics, suitable for programmable logic controllers (PLCs) and motor-control digital input modules. Unlike traditional optocoupler solutions with discrete, imprecise current limiting circuitry, the ISO1211 provides a simple, low-power solution with an accurate current limit to enable the design of compact and high-density I/O modules. It does not require field-side power supply and is configurable as sourcing or sinking inputs.

The ISO1211 operates over the supply range of 2.25 V to 5.5 V, supporting 2.5-V, 3.3-V, and 5-V controllers. A ±60-V input tolerance with reverse polarity protection helps ensure the input pins are protected in case of faults with negligible reverse current. It supports up to 4-Mbps data rates passing a minimum pulse width of 150 ns for high-speed operation. The ISO1211 device is ideal for designs that require channel-to-channel isolation and the ISO1212 device is ideal for multichannel space-constrained designs.