The ISO1211 and ISO1212 devices are isolated 24-V to 60-V digital input receivers,
compliant to IEC 61131-2 Type 1, 2, and 3 characteristics. These devices enable 9-V to 300-V DC and
AC digital input modules in programmable logic controllers (PLCs), motor-control, grid
infrastructure, and other industrial applications. Unlike traditional optocoupler solutions with
discrete, imprecise current limiting circuitry, the ISO121x devices provide a simple, low-power
solution with an accurate current limit to enable the design of compact and high-density I/O
modules. These devices do not require field-side power supply and are configurable as sourcing or
The ISO121x devices operate 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. These devices
support 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.
The ISO121x devices reduce component count, simplify system design, improve performance,
and reduce board temperatures compared to traditional solutions. For details, refer to the
How To Simplify Isolated 24-V PLC
Digital Input Module Designs TI TechNote, How To Improve Speed and Reliability of Isolated Digital
Inputs in Motor Drives TI TechNote, and How to Design Isolated Comparators for ±48V, 110V and 240V DC
and AC Detection TI TechNote.
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