ISO1211
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TI isolated 24 V digital-input receiver, SOIC-8. IEC 61131-2 Type 1/3, single resistor sets current. Datasheet-verified.
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markdownISO1211
Texas Instruments · Isolated digital input · SOIC-8
Takes a 24 V industrial field signal and turns it into a clean logic level for a controller, meeting the IEC 61131-2 Type 1, 2, and 3 digital-input specs so it behaves like a proper PLC input. A single external resistor sets the input current threshold, which cuts the power that a resistor-divider input would burn, and the input has defined switching thresholds and hysteresis for noisy field wiring. It pairs with an isolator for a fully isolated channel. A building block for PLC and industrial I/O modules.
Pinout
| Pin | Name | Type | Function |
|---|---|---|---|
| 1 | VCC1 | power_in | Power supply, side 1 (logic/controller side). Operating range 2.25V to 5.5V; supports 2.5V, 3.3V, and 5V controllers. Absolute max 6V. |
| 2 | EN | input | Output enable. OUT is enabled when EN is high or open; OUT is high-impedance when EN is low. In noisy applications, tie EN to VCC1. |
| 3 | OUT | output | Channel output (logic-side digital output representing the field-side input state). Push-pull, referenced to VCC1/GND1. IOH up to -4mA (VCC1=5V); IOL up to 4mA (VCC1=5V). |
| 4 | GND1 | power_in | Ground connection for VCC1 (logic/controller side ground reference). |
| 5 | SUB | passive | Internal connection to input chip substrate. For good thermal performance, connect this pin to a small 2mm x 2mm floating plane on the board. Do NOT connect this floating plane to FGND or any other signal or plane. |
| 6 | FGND | power_in | Field-side ground reference for the isolated field input. |
| 7 | IN | input | Field-side current input. Accepts 9V to 300V DC/AC digital input signals through an external current-limit resistor; ±60V absolute rating with reverse polarity protection. |
| 8 | SENSE | input | Field-side voltage sense pin. Used together with IN pin and external resistors to set the accurate current limit for IEC 61131-2 Type 1/2/3 compliance. Minimum pulse width at SENSE is 150ns. |
Key specifications
| Parameter | Value |
|---|---|
| Type | Digital-input receiver (24 V field) |
| Standard | IEC 61131-2 Type 1 / 2 / 3 |
| Current setting | Single external resistor |
| Input | Defined thresholds + hysteresis |
| Output | Logic level (OUT) |
| Supply | 2.25-5.5 V (logic side) |
| Package | SOIC-8 |
Ordering variants
Same part, different packaging or reel option.
ISO1211DR (SOIC-8)ISO1212DR (dual channel)
CAD (KiCad official)
- Symbol:
Isolator:ISO1211 (KiCad official) - Footprint:
Package_SO:SOIC-8_3.9x4.9mm_P1.27mm - 3D model: SOIC-8 (KiCad packages3D, STEP)
- 3D model files:
iso1211-etched.step/iso1211-etched.glbcarry the MPN laser-etched on the die in a toggleableAdom.LaserEtchgroup (Fusion-ready);iso1211.step/iso1211.glbare the bare package body.
Provenance
Data extracted from the manufacturer datasheet, not a distributor listing:
- Datasheet: Texas Instruments datasheet (47 pp, sha256
41e0bc7308dd4e0c, retrieved 2026-08-17, tier: manufacturer) - Extractor:
ds2sf(Claude). Every pin and dimension is cited to a datasheet page; it refuses to fabricate. - CAD: KiCad official libraries (CC-BY-SA 4.0).