## Overview
The Skyworks Solutions SI8421AB-D-IS is a high-speed digital isolator designed for robust galvanic isolation in industrial, automotive, and medical applications. It utilizes capacitive isolation technology to provide reinforced isolation while enabling high-speed data transmission. The device is optimized for low-power operation, high common-mode transient immunity (CMTI), and failsafe operation, ensuring signal integrity and reliable communication across isolation barriers.
## Key Features
* Digital isolator with two independent channels
* Data rate: up to 25 Mbps per channel
* Reinforced isolation: 5 kVRMS for 1 minute
* Supply voltage range: 3.0 V to 5.5 V
* Failsafe input feature ensures defined output state under input disconnection or noise conditions
* Low propagation delay: typically 17 ns per channel
* High common-mode transient immunity (CMTI): >100 kV/µs
* Low quiescent current: 1 mA per channel typical
* Compact SOIC-16 package
* Industrial operating temperature range: -40°C to +125°C
* Safety certifications for reinforced isolation suitable for industrial and medical use
## Functional Description
* Provides bidirectional digital signal isolation across a galvanic barrier
* Failsafe input ensures outputs remain in a defined logic state during high-impedance or noisy input conditions
* Independent channels enable multi-signal isolation without crosstalk
* Compatible with TTL and CMOS logic levels
* Capable of high-speed data transfer while maintaining signal integrity
* Reduces design complexity compared to traditional optocouplers and improves system reliability
## Electrical Characteristics
* Supply voltage (VDD1, VDD2): 3.0 V to 5.5 V
* Typical propagation delay: 17 ns per channel
* Maximum propagation delay mismatch: 4 ns
* High-speed digital data transfer: 25 Mbps per channel
* Typical quiescent supply current: 1 mA per channel at 25°C
* Input logic high threshold: 2.0 V minimum at 5 V supply
* Input logic low threshold: 0.8 V maximum at 5 V supply
* Output logic high voltage: VDD - 0.2 V minimum
* Output logic low voltage: 0.2 V maximum
* Common-mode transient immunity: >100 kV/µs
## Isolation and Safety
* Reinforced isolation: 5 kVRMS for 1 minute across channels and power domains
* Working voltage: 1500 V RMS continuous
* Creepage and clearance distances compliant with industrial safety standards
* Provides protection against high-voltage transients, faults, and system-level noise
* Suitable for applications requiring strict isolation, such as medical devices and industrial networks
## Package and Mechanical Information
* Package: SOIC-16
* Pin pitch: 1.27 mm
* Package dimensions: approximately 10.3 × 7.5 mm
* Lead finish: RoHS-compliant tin plating
* Compact footprint suitable for high-density PCB layouts
* Adequate thermal performance for industrial ambient temperature operation
## Applications
* Isolated RS-485, SPI, I²C, and other digital communication interfaces
* Industrial automation requiring galvanic isolation
* Motor drives, inverters, and high-speed control systems
* Medical equipment requiring reinforced isolation
* Noise-sensitive systems where failsafe input protection is critical
* High-speed digital signal isolation across power or communication barriers
The SI8421AB-D-IS provides a highly reliable, high-speed digital isolation solution with integrated failsafe input protection and exceptional common-mode transient immunity. Its compact design, reinforced isolation rating, and high data rate capability make it ideal for industrial, automotive, and medical applications where safe, robust, and deterministic digital signal isolation is required.
