Texas Instruments ISOW7721FDFMR

Overview

ISOW7721FDFMR from Texas Instruments is a two-channel galvanically isolated digital isolator with integrated low-emissions, low-noise DC-DC converter. It delivers up to 110mA at 5V or 140mA at 3.3V isolated output, supports 100Mbps data rate, features 100kV/µs CMTI, and operates across –40°C to +125°C. It enables compact isolated power + signal transfer in industrial motor control interfaces.

For engineers reviewing the ISOW7721FDFMR datasheet, ISOW7721FDFMR pinout, ISOW7721FDFMR application, or ISOW7721FDFMR equivalent, key selection criteria include integrated 550mW isolated power capability, CISPR 32 Class B compliance on 2-layer PCB, dual independent supply domains (VIO: 1.71–5.5V; VDD: 3–5.5V), and F-suffix fail-safe default-low output behavior.

Technical Context

The ISOW7721FDFMR integrates a double capacitive SiO₂ barrier for signal isolation and thin-film polymer-insulated on-chip transformers for power isolation. Its 25MHz low-frequency power converter minimizes noise coupling into adjacent logic circuits while enabling robust emissions performance without external ferrites in basic layouts.

It implements soft-start, over-voltage/under-voltage lockout, short-circuit protection, and thermal shutdown. The F-suffix variant asserts low-level default outputs during input loss-critical for safety-critical motor enable/disable signaling in factory automation systems.

Key Specifications

Pinout & Package

ISOW7721FDFMR uses a 20-pin SOIC wide-body (DFM) package with 12.83mm × 10.30mm footprint and reinforced insulation barrier. Pin functions are validated per TI SLLSFP4A datasheet Figure 4-1 and Table 4-1.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-channel isolated power + signal applications.

Compared with ADUM6421AARIZ-RL and SI88622BD-IS, the ISOW7721FDFMR uniquely combines F-suffix fail-safe outputs, VSEL-configurable 3.3V/5V isolated supply, and multi-device chaining-making it optimal for safety-critical, power-scalable industrial and medical isolation where output state predictability and flexible rail generation are mandatory.

Availability

ISOW7721FDFMR is available at Aetrix Electronics and suitable for factory automation, motor control, and medical equipment requiring stable component supply with long-term lifecycle assurance and traceable sourcing.

Supply support for ISOW7721FDFMR 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 specializing in analog, embedded processing, and connectivity solutions for industrial, automotive, and communications markets.

The ISOW7721FDFMR belongs to TI's ISOW77xx family of integrated signal + power isolators, designed specifically to replace discrete optocoupler + isolated DC-DC combinations in high-reliability industrial and medical systems.

FAQ

What does the 'F' suffix in ISOW7721FDFMR indicate?

The 'F' suffix denotes fail-safe output behavior: when input signals are lost or invalid, the ISOW7721FDFMR asserts low-level outputs on both channels. This is critical for safety-critical applications like motor enable/disable control, where a default-low state prevents unintended actuation. Non-F variants default high. The ISOW7721FDFMR implements this behavior via internal logic that monitors input validity and forces OUTA/OUTB low during fault conditions.

How does ISOW7721FDFMR achieve CISPR 32 Class B compliance on a 2-layer PCB?

The ISOW7721FDFMR achieves CISPR 32 Class B compliance on 2-layer boards through optimized internal transformer design, 25MHz low-frequency switching (reducing harmonic energy), and integrated EMI filtering structures. Its emissions profile has been validated with >5dB margin using standard 2-layer evaluation layouts-eliminating need for external ferrites or multilayer board stacks. The ISOW7721FDFMR datasheet provides recommended layout guidelines including ground plane separation and VISOIN/VISOOUT filtering options.

Can ISOW7721FDFMR support multi-device power chaining, and what is the maximum combined output?

Yes, the ISOW7721FDFMR supports multi-device power chaining using the CC and LF pins. When configured as primary (LF = GND1) and secondary (LF = VDD), two ISOW7721FDFMR devices can synchronize to deliver >1W total isolated power and >200mA combined output current. This is achieved without external clock sources or complex sequencing-each ISOW7721FDFMR handles its own regulation and protection. Chaining is documented in Section 7.3.4 of the ISOW7721FDFMR datasheet.

What are the VISOOUT voltage options for ISOW7721FDFMR, and how is selection implemented?

The ISOW7721FDFMR supports two isolated output voltages: 5V (±5%) at up to 110mA, or 3.3V (±5%) at up to 140mA. Selection is controlled by the VSEL pin: tie VSEL to GND2 for 3.3V output; tie VSEL to VISOOUT for 5V output. This hardware-selectable configuration avoids firmware dependencies and ensures deterministic power rail generation. The ISOW7721FDFMR maintains tight load regulation (<1%) and low ripple (24mV pk-pk at 5V) across both configurations.

Does ISOW7721FDFMR require external components for basic operation, and what are the minimum required connections?

The ISOW7721FDFMR operates with minimal external components: input decoupling capacitors (0.1µF + 10µF on VDD and VIO), output bulk capacitance (10µF on VISOOUT), and optional ferrite beads between VISOIN/VISOOUT for enhanced EMI suppression. Minimum required connections include VIO/GNDIO, VDD/GND1, VISOIN/GISOIN/GND2, VISOOUT, and signal pins (INA/INB/OUTA/OUTB). EN, EN_IO1, EN_IO2, CC, LF, and VSEL may be left unconnected for default operation. All required passive values and layout guidance are specified in the ISOW7721FDFMR datasheet Sections 8.3 and 8.4.