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Home > Products > Isolators > Digital Isolators

Skyworks Solutions Inc. SI8400AB-A-IS

Name: SI8400AB-A-IS
Brand: Skyworks Solutions Inc.
SKU: SI8400AB-A-IS
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: SI8400AB-A-IS

Manufacturer:: Skyworks Solutions Inc.

Category:: Digital Isolators

Package:: 8-SOIC (0.154", 3.90mm Width)

Datasheet:: SI8400AB-A-IS.pdf

Description:: DGTL ISOL 2500VRMS 2CH I2C 8SOIC

Quantity:: RFQ Add To RFQ list

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Product details

Overview

SI8400AB-A-IS from Skyworks Solutions is a bidirectional I²C isolator with two galvanically isolated, open-drain SDA and SCL channels, supporting up to 1.7 MHz bus frequency, 2500 VRMS isolation, and operation from 3.0 V to 5.5 V across –40 °C to +125 °C. It implements RF-based isolation for robust noise immunity in industrial I²C communication between isolated power domains.

For engineers reviewing the SI8400AB-A-IS datasheet, SI8400AB-A-IS pinout, SI8400AB-A-IS application, or SI8400AB-A-IS equivalent, this device delivers verified bidirectional I²C channel isolation with hot-swap capability, 35 mA sink current per channel, and UL/CSA/VDE safety certifications - critical for evaluating I²C bus segmentation in power supply monitoring, motor control interfaces, and PoE systems.

Technical Context

The SI8400AB-A-IS uses Skyworks' proprietary RF modulation architecture - not optical coupling - enabling sub-30 ns propagation delay (rising edge, 5 V), <12 ns pulse width distortion, and 25 kV/µs common-mode transient immunity. Its dual-channel design isolates both SDA and SCL lines bidirectionally without external components.

Each side features independent under-voltage lockout (UVLO+ = 2.3 V typ, hysteresis = 75 mV), start-up time ≤40 µs, and hot-swap protection that prevents data corruption when inserted into a live system. The device maintains I²C-compliant logic thresholds on Side A (I2CVT = 650 mV typ) and Side B (I2CVIL = 0.8 V max).

Key Specifications

Parameter	Value and Actual Design Meaning
Isolation Rating	2500 VRMS for 1 minute - certified per UL 1577, CSA 5A, and VDE 0884-2 for reinforced insulation in industrial environments.
I²C Bus Frequency	Up to 1.7 MHz - supports standard/fast-mode-plus I²C timing without clock stretching or protocol modification.
Supply Voltage Range	3.0 V to 5.5 V - enables direct interface with 3.3 V and 5 V microcontrollers and power rails without level shifters.
Output Sink Current	35 mA per channel (Side B) - drives standard I²C pull-up resistors (e.g., 1–10 kΩ) while maintaining VOL ≤400 mV at full load.
Propagation Delay	25 ns (A→B rising, 5 V) - ensures minimal timing budget impact on high-speed I²C arbitration and ACK/NACK cycles.
Operating Temperature	–40 °C to +125 °C - qualified for under-hood automotive subsystems, industrial PLC backplanes, and motor drive control boards.
Common-Mode Transient Immunity	25 kV/µs - suppresses noise-induced glitches during switching events in power electronics and inverters.

Pinout & Package

SI8400AB-A-IS is housed in an 8-pin narrow-body SOIC package (SOIC-8 NB), with creepage and clearance of 4.9 mm and 4.01 mm respectively, compliant with IEC 60664-1 for reinforced insulation.

Pin	Circuit Role	Design Meaning
1	AVDD	Side A primary supply (3.0–5.5 V); powers transmitter circuitry and I²C input stage.
2	ASDA	Side A bidirectional I²C SDA line; open-drain output with 35 mA sink capability and internal logic threshold.
3	ASCL	Side A bidirectional I²C SCL line; identical electrical behavior to ASDA, synchronized for clock domain isolation.
4	AGND	Side A ground reference; must be isolated from BGND with ≥4.9 mm clearance for safety compliance.
5	BGND	Side B ground reference; forms isolation barrier boundary with AGND; no DC continuity.
6	BSCL	Side B bidirectional I²C SCL line; mirrors ASCL state with <30 ns delay; supports hot-swap insertion.
7	BSDA	Side B bidirectional I²C SDA line; maintains I²C bus integrity during arbitration and multi-master contention.
8	BVDD	Side B supply (3.0–5.5 V); powers receiver circuitry and output drivers; independent UVLO monitoring.

Key Features

Feature	Design Value
Bidirectional I²C channel isolation	Enables transparent, protocol-compliant isolation of both SDA and SCL without external direction-control logic or pull-ups on isolated side.
RF-based isolation architecture	Delivers 3× lower propagation delay and 2× higher CMTI vs. optocouplers, eliminating LED aging and temperature drift concerns.
Hot-swap capable	Prevents bus lockup or data corruption when SI8400AB-A-IS is inserted into a powered system - outputs enter Hi-Z until UVLO exit.
Independent UVLO per side	Allows asymmetric power sequencing: Side A can remain active while Side B powers up/down, supporting modular power domain management.
RoHS-compliant SOIC-8 NB package	Meets IPC-7351B land pattern standards; 5.0 mm × 6.2 mm footprint enables high-density PCB layouts in space-constrained industrial modules.

Applications

Industrial Power Supply Monitoring	Motor Control Interface
Use Scenario: Isolating I²C communication between a host MCU (3.3 V, 25 °C ambient) and isolated digital power controller IC (5 V, 85 °C junction) in a 48 V DC-DC module. IC Role / Device Role / Timing Role: Bidirectional I²C isolator bridging primary and secondary sides; preserves clock synchronization and ACK/NACK timing integrity across isolation barrier. Use Value: Enables real-time telemetry (voltage, current, temperature) without compromising safety certification or introducing bus arbitration delays >100 ns.	Use Scenario: Connecting an ARM Cortex-M7 MCU to isolated gate driver ICs and current-sense ADCs over I²C in a three-phase inverter stack. IC Role / Device Role / Timing Role: Galvanic barrier for SDA/SCL signals between control logic and high-noise power stage; withstands 25 kV/µs transients during IGBT switching. Use Value: Prevents ground-loop-induced communication errors and eliminates need for optocoupler-based level-shifting circuits.
Power over Ethernet (PoE) PD Controller	Intelligent Battery Management System
Use Scenario: Isolating I²C configuration and status reads between PoE PSE controller (primary side) and IEEE 802.3af/at PD interface IC (secondary side) in Class 4/5 injectors. IC Role / Device Role / Timing Role: Safety-rated I²C isolator meeting UL 1577 2500 VRMS requirement; supports hot-plug detection and classification handshake timing. Use Value: Maintains I²C clock fidelity up to 1.7 MHz during dynamic load changes, ensuring accurate PD signature verification within 10 ms.	Use Scenario: Interfacing fuel gauge IC (e.g., bq27441) on battery pack side with system MCU on main board via I²C in UPS or EV auxiliary systems. IC Role / Device Role / Timing Role: Reinforced insulation barrier preventing fault currents from propagating between high-energy battery cells and low-voltage control logic. Use Value: Supports continuous SOC/SOH reporting at 400 kHz without signal degradation, even under ±100 V common-mode transients.

Industrial Power Supply Monitoring

Motor Control Interface

Use Scenario: Isolating I²C communication between a host MCU (3.3 V, 25 °C ambient) and isolated digital power controller IC (5 V, 85 °C junction) in a 48 V DC-DC module.

IC Role / Device Role / Timing Role: Bidirectional I²C isolator bridging primary and secondary sides; preserves clock synchronization and ACK/NACK timing integrity across isolation barrier.

Use Value: Enables real-time telemetry (voltage, current, temperature) without compromising safety certification or introducing bus arbitration delays >100 ns.

Use Scenario: Connecting an ARM Cortex-M7 MCU to isolated gate driver ICs and current-sense ADCs over I²C in a three-phase inverter stack.

IC Role / Device Role / Timing Role: Galvanic barrier for SDA/SCL signals between control logic and high-noise power stage; withstands 25 kV/µs transients during IGBT switching.

Use Value: Prevents ground-loop-induced communication errors and eliminates need for optocoupler-based level-shifting circuits.

Power over Ethernet (PoE) PD Controller

Intelligent Battery Management System

Use Scenario: Isolating I²C configuration and status reads between PoE PSE controller (primary side) and IEEE 802.3af/at PD interface IC (secondary side) in Class 4/5 injectors.

IC Role / Device Role / Timing Role: Safety-rated I²C isolator meeting UL 1577 2500 VRMS requirement; supports hot-plug detection and classification handshake timing.

Use Value: Maintains I²C clock fidelity up to 1.7 MHz during dynamic load changes, ensuring accurate PD signature verification within 10 ms.

Use Scenario: Interfacing fuel gauge IC (e.g., bq27441) on battery pack side with system MCU on main board via I²C in UPS or EV auxiliary systems.

IC Role / Device Role / Timing Role: Reinforced insulation barrier preventing fault currents from propagating between high-energy battery cells and low-voltage control logic.

Use Value: Supports continuous SOC/SOH reporting at 400 kHz without signal degradation, even under ±100 V common-mode transients.

Equivalent & Alternatives

The following parts are listed as comparable options for similar I²C isolator applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
ADUM1250ARZ	2-channel, 1 Mbps max I²C rate; 2500 VRMS isolation; CMOS input/output; no integrated I²C logic - requires external pull-ups and direction control.	Limited to 1 Mbps; lacks native I²C bus arbitration support; higher propagation delay (60 ns typical).	Choose ADUM1250ARZ only if legacy design reuse or cost sensitivity outweighs need for 1.7 MHz operation and simplified layout.
ISO1540DR	2-channel, 1 Mbps I²C isolator; 2500 VRMS; integrated I²C logic; 3.3 V only supply; no 5 V compatibility.	Not rated for 5 V operation or –40 °C to +125 °C extended range; lower CMTI (25 kV/µs same, but unverified above 100 °C).	Select ISO1540DR only for 3.3 V-only, commercial-temperature applications where 1.7 MHz bandwidth is unnecessary.

Compared with ADUM1250ARZ and ISO1540DR, SI8400AB-A-IS provides higher I²C speed (1.7 MHz), wider supply (3.0–5.5 V), full extended temperature qualification, and native bidirectional logic - reducing BOM count and improving timing margin in demanding industrial designs.

Availability

SI8400AB-A-IS is available at Aetrix Electronics and suitable for industrial power supply monitoring, motor control interfaces, and Power over Ethernet (PoE) systems requiring stable component supply, long-term lifecycle assurance, and safety-certified isolation performance.

Supply support for SI8400AB-A-IS 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

Skyworks Solutions is a global semiconductor company specializing in analog and mixed-signal connectivity solutions, with leadership in RF, timing, and isolation technologies for high-reliability applications.

The Si840x family was designed specifically for galvanic isolation of I²C and SMBus interfaces in industrial, automotive, and enterprise infrastructure systems - prioritizing speed, safety certification, and ease of integration over generic digital isolation.

FAQ

What is the maximum I²C bus frequency supported by the SI8400AB-A-IS?

The SI8400AB-A-IS supports a maximum I²C bus frequency of 1.7 MHz, verified across the full operating temperature range (–40 °C to +125 °C) and supply voltage range (3.0 V to 5.5 V). This enables compatibility with fast-mode-plus I²C devices without protocol adaptation or clock stretching, and is measured with standard test conditions per Figure 2 in the datasheet.

Does the SI8400AB-A-IS require external pull-up resistors on the I²C bus lines?

Yes, the SI8400AB-A-IS requires external pull-up resistors on both ASDA/ASCL and BSDA/BSCL lines, as its outputs are open-drain. Typical values range from 1 kΩ to 10 kΩ depending on bus capacitance and speed; the device's 35 mA sink capability on Side B ensures reliable low-level assertion even with lower-value pull-ups for 1.7 MHz operation.

Is the SI8400AB-A-IS certified for reinforced insulation per international safety standards?

Yes, the SI8400AB-A-IS is certified for reinforced insulation per UL 1577 (2500 VRMS), CSA Component Acceptance Notice 5A (IEC 60950-1/61010-1), and VDE 0884-2 (IEC 60747-5-2). These certifications are production-tested per device, with working voltage ratings up to 560 Vpeak and creepage/clearance of 4.9 mm / 4.01 mm in the SOIC-8 NB package.

How does the SI8400AB-A-IS handle power sequencing between Side A and Side B?

The SI8400AB-A-IS features independent under-voltage lockout (UVLO) on AVDD and BVDD, allowing asymmetric power sequencing. If one side loses power, its outputs go Hi-Z while the powered side remains functional - enabling safe hot-swap insertion and graceful degradation in modular power systems without bus contention or latch-up.

What is the propagation delay specification for the SI8400AB-A-IS at 5 V operation?

At 5 V operation, the SI8400AB-A-IS exhibits a typical propagation delay of 25 ns (A→B rising), 15 ns (A→B falling), 20 ns (B→A rising), and 9.0 ns (B→A falling), measured under defined test conditions (no bus capacitance, R1 = 1400 Ω, R2 = 499 Ω). Pulse width distortion is limited to 9.0 ns (A→B) and 11 ns (B→A), preserving I²C timing margins.

SI8400AB-A-IS Specifications

Product attributes: Attribute value

Manufacturer:: Skyworks Solutions Inc.

Series:: -

Package/Case:: 8-SOIC (0.154", 3.90mm Width)

Packaging:: Tube

Product Status:: Not For New Designs

Technology:: Capacitive Coupling

Type:: I2C

Isolated Power:: No

Number of Channels:: 2

Inputs - Side 1/Side 2:: 2/2

Channel Type:: Bidirectional

Voltage - Isolation:: 2500Vrms

Common Mode Transient Immunity (Min):: 25kV/µs (Typ)

Data Rate:: -

Propagation Delay tpLH / tpHL (Max):: -

Pulse Width Distortion (Max):: -

Rise / Fall Time (Typ):: -

Voltage - Supply:: 3V ~ 5.5V

Grade:: -

Qualification:: -

Operating Temperature:: -40°C ~ 125°C

Mounting Type:: Surface Mount

Supplier Device Package:: 8-SOIC

SI8400AB-A-IS FAQ

1.How can I place an order for SI8400AB-A-IS through Aetrix?

Please submit a Request for Quotation (RFQ) for SI8400AB-A-IS on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for SI8400AB-A-IS reliable?

The price and inventory of SI8400AB-A-IS are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SI8400AB-A-IS is usually 5 days.

3.What payment methods are accepted for SI8400AB-A-IS?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SI8400AB-A-IS transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for SI8400AB-A-IS?

SI8400AB-A-IS orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your SI8400AB-A-IS order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for SI8400AB-A-IS?

For technical support, including SI8400AB-A-IS datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SI8400AB-A-IS requirements.

6.How does Aetrix verify that SI8400AB-A-IS is sourced from the original manufacturer or authorized distributors?

All SI8400AB-A-IS products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that SI8400AB-A-IS meets industry standards.

7.What is the process for return or replacement of SI8400AB-A-IS?

All SI8400AB-A-IS units undergo pre-shipment inspection (PSI). If there is an issue with SI8400AB-A-IS, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The SI8400AB-A-IS part is unused and in its original packaging.

Return procedure for SI8400AB-A-IS:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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