Texas Instruments ISO7420FED

Overview

ISO7420FED from Texas Instruments is a dual-channel, unidirectional digital isolator with galvanic isolation up to 2500 VRMS (1 min UL) and 4242 VPK (VDE), TTL-compatible input thresholds, 50-Mbps signaling rate, and default-low fail-safe output behavior due to the 'F' suffix. It operates across 3.0–5.5-V supplies on both sides and supports level translation between 3.3-V and 5-V domains in industrial fieldbus and motor control interfaces.

For engineers reviewing the ISO7420FED datasheet, ISO7420FED pinout, ISO7420FED application, or ISO7420FED equivalent, this page delivers verified functional identity, SOIC-8 package mapping, confirmed dual unidirectional channel architecture, fail-safe low-default behavior, and real-world isolation performance metrics for noise-critical signal integrity design.

Technical Context

The ISO7420FED implements two independent, input-to-output directional channels separated by a silicon dioxide (SiO₂) insulation barrier-no integrated noise filter, enabling 7-ns typical propagation delay. Its dual supply architecture (VCCI/GNDI and VCCO/GNDO) enables true bidirectional voltage-level translation while maintaining galvanic separation.

Fail-safe operation is hardware-defined: upon input-side power loss, outputs transition to logic low within 6 μs. Input thresholds meet TTL specifications (VIL ≤ 0.8 V, VIH ≥ 2 V), and common-mode transient immunity is rated at 25–50 kV/μs across temperature.

Key Specifications

Pinout & Package

ISO7420FED uses a narrow-body SOIC-8 package (4.90 mm × 3.91 mm), with galvanically isolated input and output sides. Power and ground pins are segregated: VCCI/GNDI serve the input domain; VCCO/GNDO serve the output domain.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-channel digital isolator applications.

Compared with ISO7420ED and SI8620ED-B-IS, the ISO7420FED uniquely combines default-low fail-safe behavior, SiO₂-based isolation reliability, and strict pin compatibility within the ISO742x family-making it optimal for safety-critical motor control where undefined outputs during power loss are unacceptable.

Availability

ISO7420FED is available at Aetrix Electronics and suitable for industrial fieldbus nodes, servo control interfaces, motor feedback systems, and isolated power supply monitoring requiring stable component supply and long-lifecycle support.

Supply support for ISO7420FED 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 leader delivering analog, embedded processing, and connectivity solutions for industrial, automotive, and communications markets.

The ISO742x product line was designed specifically for high-reliability digital signal isolation in harsh industrial environments-emphasizing low propagation delay, robust CMTI, and long-term isolation barrier stability.

FAQ

What does the 'F' in ISO7420FED signify?

The 'F' suffix in ISO7420FED denotes fail-safe default-low output behavior: when input-side power (VCCI) is lost or invalid, both OUTA and OUTB transition to logic low within 6 μs. This is a hardware-defined feature critical for preventing unintended activation in motor gate drivers or safety interlocks. The ISO7420FED maintains this behavior across its full –40°C to +125°C operating range.

Does ISO7420FED support level translation between 3.3-V and 5-V domains?

Yes, ISO7420FED supports bidirectional level translation: its inputs tolerate 0–5.5 V regardless of VCCI supply (e.g., 5-V signals accepted at 3.3-V VCCI), and outputs swing rail-to-rail relative to VCCO (e.g., 5-V outputs driven from 3.3-V VCCI). This eliminates external level shifters in mixed-voltage systems such as PLC I/O modules interfacing with both 3.3-V MCUs and 5-V sensors.

What is the maximum signaling rate supported by ISO7420FED?

The ISO7420FED supports a maximum signaling rate of 50 Mbps under recommended operating conditions (VCC = 3.0–5.5 V, TA = –40°C to +125°C). At 25 Mbps, typical propagation delay remains 7 ns (VCC = 5 V), and pulse width distortion stays below 3 ns-enabling reliable use in high-speed serial protocols like SPI clock extension and fast encoder interfaces.

How does ISO7420FED differ from ISO7421FED?

The ISO7420FED has both channels configured input-to-output (unidirectional, same direction), whereas ISO7421FED has one channel input-to-output and the other output-to-input (bidirectional channel pairing). Pin assignments differ: INA/INB are on Pins 2/3 for ISO7420FED but on Pins 2/3 and 7/2 respectively for ISO7421FED. This makes them functionally incompatible despite identical packaging and isolation specs.

Is ISO7420FED certified for industrial safety standards?

Yes, ISO7420FED is certified to multiple industrial safety standards: 4242 VPK per DIN V VDE V 0884-10, 2500 VRMS per UL 1577 (1 minute), CSA Component Acceptance Notice 5A, and IEC 61010-1. These certifications validate its suitability for reinforced insulation in programmable logic controllers, motor drives, and other safety-related industrial equipment requiring creepage/clearance compliance.