Texas Instruments ISO1211D

Overview

ISO1211D from Texas Instruments is a single-channel, capacitive-isolated 24V–60V digital input receiver compliant with IEC 61131-2 Type 1/2/3 characteristics. It provides field-side current limiting (2.2–2.47 mA for Type 3), ±60V reverse-polarity input protection, and 4 Mbps data rate - enabling compact, low-power PLC digital input modules without field-side power supply.

For engineers reviewing the ISO1211D datasheet, ISO1211D pinout, ISO1211D application, or ISO1211D equivalent, this device serves as a high-CMTI (±70 kV/µs), functional-safety-capable replacement for optocoupler-based input receivers in industrial control systems requiring precise current limiting, wide input voltage tolerance, and channel-to-channel isolation.

Technical Context

The ISO1211D implements a fully integrated capacitive isolation barrier between field-side (IN/SENSE/FGND) and controller-side (OUT/VCC1/GND1) domains. Its internal feedback loop regulates input current via external RSENSE, eliminating discrete current-limiting components while maintaining IEC 61131-2 threshold hysteresis (1.0–1.2 V) and transition accuracy across –40°C to +125°C.

It supports configurable sourcing/sinking operation, wire-break detection, and EN-pin multiplexing of output signals. The SOIC-8 package integrates dual-side thermal management via SUB pin (recommended 2 mm × 2 mm floating thermal pad), with RθJA = 146.1°C/W and safety-limited power dissipation up to 450 mW at TJ = 150°C.

Key Specifications

Pinout & Package

ISO1211D is housed in an 8-pin SOIC (D) package with 4.90 mm × 3.91 mm body size and creepage/clearance ≥ 4 mm. Thermal performance is enhanced by connecting the SUB pin to a dedicated 2 mm × 2 mm floating copper plane.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar isolated digital input receiver applications.

Compared with Si87xx and ADUM124x, ISO1211D delivers complete input-receiver functionality in one IC - integrating precision current limiting, IEC-compliant thresholds, reverse-polarity protection, and wire-break detection - reducing bill-of-materials count by ≥4 components and eliminating front-end calibration.

Availability

ISO1211D is available at Aetrix Electronics and suitable for programmable logic controller (PLC) digital input modules, motor drive I/O subsystems, and industrial data acquisition units requiring stable component supply, long-term lifecycle support, and functional safety documentation.

Supply support for ISO1211D includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a global semiconductor company focused on analog and embedded processing technologies, serving industrial, automotive, and communications markets with high-reliability components.

ISO1211D belongs to TI's isolated interface product line, designed specifically for robust, low-power, safety-certified digital input conditioning in harsh industrial environments - replacing aging optocoupler-based architectures.

FAQ

What is the maximum input voltage the ISO1211D can withstand without damage?

The ISO1211D supports an absolute maximum input voltage of ±60 V on its IN and SENSE pins, with built-in reverse polarity protection that prevents damage during wiring faults. This rating is validated per IEC 61000-4-5 surge testing and enables direct connection to 24V, 48V, and 60V industrial field buses without external clamping components. The ISO1211D maintains safe operation within this range across its full –40°C to +125°C ambient temperature specification.

Does the ISO1211D require an external power supply on the field side?

No, the ISO1211D does not require a field-side power supply. It derives operating power directly from the input signal via its precision current-limiting architecture - drawing only 2.2–2.47 mA (Type 3) from the field source. This self-powered operation eliminates the need for isolated DC/DC converters or auxiliary supplies on the field side, significantly simplifying system architecture and reducing bill-of-materials cost in PLC and motor drive applications.

How does the ISO1211D achieve IEC 61131-2 Type 3 compliance?

The ISO1211D achieves IEC 61131-2 Type 3 compliance through integrated voltage threshold and hysteresis control: it guarantees a low-level threshold (VIL) of 6.5–7.0 V and high-level threshold (VIH) of 8.2–8.55 V with 1.0–1.2 V hysteresis when configured with RSENSE = 562 Ω and RTHR = 0 Ω. These values are maintained across –40°C to +125°C and meet the standard's requirements for noise immunity, transition speed, and off-state leakage - all without external component tuning.

Can the ISO1211D be used in both sourcing and sinking input configurations?

Yes, the ISO1211D supports both sourcing and sinking input configurations via external resistor network selection. When the field-side common is connected to FGND, the device operates as a sinking input; when FGND is left floating and the field return is tied to IN, it functions as a sourcing input. This flexibility allows seamless integration with legacy 2-wire and 3-wire sensor topologies commonly found in industrial automation systems.

What safety certifications does the ISO1211D hold?

The ISO1211D holds DIN EN IEC 60747-17 (VDE 0884-17), UL 1577 (2500 VRMS), IEC 60950-1, IEC 62368-1, IEC 61010-1, and GB 4943.1-2011 certifications. It is rated for basic insulation with 400 VRMS working voltage and 3600 VPK transient isolation. TI provides functional safety documentation including failure mode analysis and FIT rate data to support ISO 13849 and IEC 61508 system-level certification efforts.