Texas Instruments ISO721DRG4

Overview

ISO721DRG4 from Texas Instruments is a single-channel, high-speed digital isolator with silicon dioxide (SiO₂) insulation barrier, delivering 100 Mbps signaling rate, 12 ns typical propagation delay, and 0.5 ns typical pulse skew. It operates from 3.3 V or 5 V supplies, supports –40°C to +125°C ambient temperature, and provides failsafe output logic-high on input power loss - used in industrial fieldbus interfaces requiring galvanic isolation and noise immunity.

For engineers reviewing the ISO721DRG4 datasheet, ISO721DRG4 pinout, ISO721DRG4 application, or ISO721DRG4 equivalent, this page delivers verified technical context, package mapping, real-world use cases, and validated alternative options for factory automation, servo control, and data acquisition systems where signal integrity and safety certification are critical.

Technical Context

The ISO721DRG4 uses capacitive coupling across a SiO₂ isolation barrier to transmit logic transitions via differential encoding and refresh pulses; its failsafe circuit asserts high-impedance-to-high-level output within 3 µs of input power loss. It features TTL input thresholds with integrated 2 ns noise filtering and supports dual independent supply domains (VCC1/VCC2) for level-shifting between 3.3 V and 5 V logic domains.

Unlike ISO722 variants, ISO721DRG4 lacks output enable (EN) functionality and does not support high-impedance output states. Its isolation barrier is rated for 4000 VPK per VDE 0884-17 and certified to UL 1577 (2500 VRMS), IEC 62368-1, and IEC 61010-1 - enabling use in safety-critical industrial equipment without external protection circuitry.

Key Specifications

Pinout & Package

ISO721DRG4 is housed in an 8-pin SOIC (D package) with 4.90 mm × 3.91 mm body size and 4.9 mm × 6 mm overall footprint. The device has no output enable pin and uses dedicated isolated power and ground terminals for each side of the barrier.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ISO721DR and ISO721MDRG4, the ISO721DRG4 offers optimal balance of noise immunity, industrial temperature range, and proven 100 Mbps reliability - making it the preferred choice for fieldbus and servo applications where robustness outweighs marginal speed gains.

Availability

ISO721DRG4 is available at Aetrix Electronics and suitable for factory automation, servo control, and data acquisition systems requiring stable component supply, long-lifecycle support, and certified isolation performance.

Supply support for ISO721DRG4 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 specializing in analog, embedded processing, and high-reliability components for industrial, automotive, and communications markets.

The ISO72x family was designed specifically for industrial digital isolation - targeting fieldbus interfaces, motor drives, and programmable logic controllers where safety certification, noise immunity, and long-term reliability are mandatory.

FAQ

What is the maximum signaling rate supported by ISO721DRG4?

The ISO721DRG4 supports a maximum signaling rate of 100 Mbps under recommended operating conditions. This is confirmed in the device comparison table and switching characteristics sections of the official TI datasheet (SLLS629O). The ISO721DRG4 is not rated for 150 Mbps operation - that capability belongs exclusively to the ISO721M variant. At 100 Mbps, the device maintains specified propagation delay, skew, and jitter performance across its full temperature range.

Does ISO721DRG4 include an output enable (EN) pin?

No, ISO721DRG4 does not have an output enable pin. Pin configuration diagrams and Table 5-1 in the TI datasheet confirm that EN is absent on ISO721 and ISO721M devices. Only ISO722 and ISO722M variants include pin 7 as an active-low EN terminal. Therefore, ISO721DRG4 outputs are always active and cannot be placed into high-impedance state - a key distinction affecting system-level bus sharing design.

What safety certifications apply to ISO721DRG4?

ISO721DRG4 is certified to DIN EN IEC 60747-17 (VDE 0884-17) for reinforced isolation, UL 1577 (2500 VRMS withstand voltage), IEC 62368-1, and IEC 61010-1. These certifications are explicitly listed in Section 6.8 of the TI datasheet and verified in the orderable addendum. The device meets creepage and clearance requirements of 4 mm for the D-package SOIC, supporting use in safety-rated industrial equipment without additional barrier reinforcement.

How does the failsafe function operate in ISO721DRG4?

The ISO721DRG4 asserts a logic-high output within 3 µs if the input side (VCC1 or IN) loses power or becomes un-driven. This behavior is implemented via internal dc-refresh pulse monitoring: failure to receive the periodic update pulse across the isolation barrier for >4 µs triggers the failsafe circuit. The feature is documented in the Description section and Figure 7-4 of the TI datasheet, ensuring predictable output state during brownouts or cable disconnects in safety-critical I/O modules.

Can ISO721DRG4 operate with mixed supply voltages (e.g., 3.3 V on VCC1 and 5 V on VCC2)?

Yes, ISO721DRG4 supports mixed-supply operation: VCC1 and VCC2 may be independently set to 3.3 V or 5 V within their respective recommended ranges (3 V–5.5 V). Electrical Characteristics tables (6.9, 6.12, 6.15) explicitly specify performance under 3.3 V/5 V and 5 V/3.3 V configurations. Input pins are 5 V tolerant when VCC1 = 3.3 V, and outputs drive CMOS loads compatible with either rail - enabling seamless level translation in heterogeneous digital systems.