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Home > Products > Isolators > Digital Isolators

Skyworks Solutions Inc. SI8400AB-B-IS

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

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Part No.:: SI8400AB-B-IS

Manufacturer:: Skyworks Solutions Inc.

Category:: Digital Isolators

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

Datasheet:: SI8400AB-B-IS.pdf

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

Quantity:: RFQ Add To RFQ list

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Product details

Overview

SI8400AB-B-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 I²C clock rates, 2500 VRMS isolation, and operation from 3.0–5.5 V across –40 to +125 °C. It implements RF-based isolation for low propagation delay (≤29 ns), high CMTI (25 kV/µs), and hot-swap robustness in SMBus/I²C bus isolation applications.

For engineers reviewing the SI8400AB-B-IS datasheet, SI8400AB-B-IS pinout, SI8400AB-B-IS application, or SI8400AB-B-IS equivalent, this page delivers verified specifications, SOIC-8 narrow-body package details, I²C timing compliance, safety certifications (UL, CSA, VDE), and real-world design context for industrial power management, motor control, and PoE systems.

Technical Context

The SI8400AB-B-IS uses Skyworks' proprietary RF modulation architecture-replacing optical coupling with on/off-keyed RF carriers across a semiconductor isolation barrier-to achieve superior noise immunity, stable performance over temperature/age, and sub-30 ns propagation delays. Its dual-channel design supports fully independent bidirectional SDA/SCL isolation without external components.

Each side features independent under-voltage lockout (UVLO) with 2.15–2.5 V rising threshold and 45–95 mV hysteresis, enabling reliable startup/shutdown sequencing. The device maintains I²C-compliant logic thresholds (Side A: VT = 450–780 mV; Side B: VIH ≥ 2.0 V, VIL ≤ 0.8 V) and 35 mA sink capability on SDA/SCL outputs for standard pull-up configurations.

Key Specifications

Parameter	Value and Actual Design Meaning
I²C Max Frequency	1.7 MHz - Supports full-speed I²C and SMBus protocols without clock stretching or timing violations.
Isolation Rating	2500 VRMS - Certified for reinforced insulation per UL 1577, CSA 5A, and VDE IEC 60747-5-2; enables safe separation between primary and secondary domains in AC-powered systems.
Propagation Delay	≤29 ns (A→B rising, 5 V) - Enables tight timing margins in high-speed digital interfaces and reduces bus arbitration latency.
Supply Voltage Range	3.0–5.5 V - Compatible with both 3.3 V and 5 V logic domains on either side, simplifying mixed-voltage system integration.
Operating Temperature	–40 to +125 °C - Qualified for under-hood automotive, industrial motor drives, and high-ambient-power-supply applications.
CMTI	25 kV/µs - Ensures reliable data transmission in noisy environments such as motor inverters and switch-mode power supplies.
Output Sink Current	35 mA (SDA/SCL) - Drives standard 1–10 kΩ pull-up resistors while maintaining valid I²C low-level voltage (<0.8 V at 3 mA).

Pinout & Package

SI8400AB-B-IS is housed in an 8-pin narrow-body SOIC package (SOIC-8 NB), with 4.9 mm clearance and 4.01 mm creepage, compliant with reinforced insulation requirements for up to 300 VRMS working voltage (IEC 61010-1).

Pin	Circuit Role	Design Meaning
1	AVDD	Primary-side supply input (3.0–5.5 V); powers Side A transmitter and internal circuitry.
2	ASDA	Side A bidirectional I²C SDA channel - open-drain, 35 mA sink, compatible with standard I²C pull-ups.
3	ASCL	Side A bidirectional I²C SCL channel - identical electrical behavior to ASDA; supports clock stretching.
4	AGND	Primary-side ground reference; must be separated from BGND by isolation barrier.
5	BGND	Secondary-side ground reference; forms isolation boundary with AGND.
6	BSCL	Side B bidirectional I²C SCL channel - electrically mirrored to ASCL with matched timing and drive strength.
7	BSDA	Side B bidirectional I²C SDA channel - fully independent of ASDA; enables true galvanic bus segmentation.
8	BVDD	Secondary-side supply input (3.0–5.5 V); powers Side B receiver and output drivers.

Key Features

Feature	Design Value
RF-based galvanic isolation	Eliminates LED aging and temperature drift of optocouplers; delivers stable propagation delay and CMTI over lifetime and temperature.
Hot-swap capable I²C interface	Prevents data corruption during live insertion via built-in protection circuits that manage unpowered-side transitions.
Independent UVLO per side	Enables asymmetric power sequencing (e.g., BVDD powered before AVDD) without latch-up or undefined outputs.
Open-drain I²C outputs with 35 mA sink	Directly replaces legacy optocoupler-based I²C isolators without external transistors or level shifters.
RoHS-compliant SOIC-8 narrow body	Standard footprint compatible with existing PCB layouts; meets IPC-7351B land pattern requirements (ref. Skyworks doc p.27).

Applications

Industrial Motor Control	Power over Ethernet (PoE)
Use Scenario: Isolating I²C communication between MCU (primary side) and isolated gate drivers or current sensors in 3-phase inverter stacks. IC Role / Device Role / Timing Role: Bidirectional I²C isolator bridging safety-critical high-voltage domain and low-voltage control domain. Use Value: Maintains 1.7 MHz I²C throughput while providing 2500 VRMS isolation and 25 kV/µs CMTI to prevent noise-induced bus lockup during PWM switching.	Use Scenario: Enabling I²C configuration and telemetry between PD controller (secondary side) and upstream PSE management IC (primary side) in IEEE 802.3af/at/bt systems. IC Role / Device Role / Timing Role: Galvanic barrier for SMBus/I²C signals across PoE isolation boundary, preserving hot-swap and fault reporting integrity. Use Value: Supports fast parameter read/write (e.g., power class, fault status) without compromising isolation rating or introducing timing jitter into power negotiation sequences.
Intelligent Power Systems	Isolated Digital Power Supply Communications
Use Scenario: Interfacing microcontrollers with isolated DC-DC converter modules (e.g., PMBus-enabled POL regulators) in server VRMs or telecom rectifiers. IC Role / Device Role / Timing Role: Robust I²C isolator ensuring reliable telemetry (voltage, current, temperature) and configuration commands across isolation barrier. Use Value: Delivers <29 ns propagation delay and ±15 ns pulse-width distortion to meet PMBus timing budgets while surviving high dv/dt transients near power stages.	Use Scenario: Isolating I²C links between host processor and isolated ADCs, DACs, or digital isolators in multi-rail programmable power supplies. IC Role / Device Role / Timing Role: Dual-channel bidirectional isolator preserving signal integrity for both SDA and SCL lines in feedback and control loops. Use Value: Enables simultaneous read/write operations at full I²C speed without added latency or bus arbitration overhead from discrete isolation solutions.

Industrial Motor Control

Power over Ethernet (PoE)

Use Scenario: Isolating I²C communication between MCU (primary side) and isolated gate drivers or current sensors in 3-phase inverter stacks.

IC Role / Device Role / Timing Role: Bidirectional I²C isolator bridging safety-critical high-voltage domain and low-voltage control domain.

Use Value: Maintains 1.7 MHz I²C throughput while providing 2500 VRMS isolation and 25 kV/µs CMTI to prevent noise-induced bus lockup during PWM switching.

Use Scenario: Enabling I²C configuration and telemetry between PD controller (secondary side) and upstream PSE management IC (primary side) in IEEE 802.3af/at/bt systems.

IC Role / Device Role / Timing Role: Galvanic barrier for SMBus/I²C signals across PoE isolation boundary, preserving hot-swap and fault reporting integrity.

Use Value: Supports fast parameter read/write (e.g., power class, fault status) without compromising isolation rating or introducing timing jitter into power negotiation sequences.

Intelligent Power Systems

Isolated Digital Power Supply Communications

Use Scenario: Interfacing microcontrollers with isolated DC-DC converter modules (e.g., PMBus-enabled POL regulators) in server VRMs or telecom rectifiers.

IC Role / Device Role / Timing Role: Robust I²C isolator ensuring reliable telemetry (voltage, current, temperature) and configuration commands across isolation barrier.

Use Value: Delivers <29 ns propagation delay and ±15 ns pulse-width distortion to meet PMBus timing budgets while surviving high dv/dt transients near power stages.

Use Scenario: Isolating I²C links between host processor and isolated ADCs, DACs, or digital isolators in multi-rail programmable power supplies.

IC Role / Device Role / Timing Role: Dual-channel bidirectional isolator preserving signal integrity for both SDA and SCL lines in feedback and control loops.

Use Value: Enables simultaneous read/write operations at full I²C speed without added latency or bus arbitration overhead from discrete isolation solutions.

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 bus arbitration handling.	Limited to 1 Mbps; lacks native I²C timing optimization and hot-swap protection circuits present in SI8400AB-B-IS.	Choose ADUM1250ARZ only if lower data rate suffices and system-level I²C protocol handling is already implemented externally.
ISO1540DR	2-channel, 1 Mbps max I²C rate; 2500 VRMS isolation; integrated I²C logic but no hot-swap support; higher typical propagation delay (45 ns).	Not rated for hot-swap events; less robust against unpowered insertion; lower CMTI (25 kV/µs same, but no transient suppression circuitry).	Select ISO1540DR where cost sensitivity outweighs need for hot-swap resilience and sub-30 ns timing in high-noise environments.

Compared with ADUM1250ARZ and ISO1540DR, SI8400AB-B-IS provides native 1.7 MHz I²C support, lower propagation delay, and dedicated hot-swap protection-making it optimal for high-speed, high-reliability industrial and PoE applications where bus uptime and timing margin are critical.

Availability

SI8400AB-B-IS is available at Aetrix Electronics and suitable for industrial motor control, Power over Ethernet, and intelligent power systems requiring stable component supply, long-term lifecycle support, and certified 2500 VRMS isolation.

Supply support for SI8400AB-B-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 leader in analog and mixed-signal semiconductors, specializing in RF, timing, and isolation technologies for wireless infrastructure, automotive, and industrial markets.

The Si840x family was designed specifically for robust, high-speed I²C and SMBus isolation in harsh environments-replacing optocouplers with RF-based digital isolators offering superior longevity, temperature stability, and EMI immunity.

FAQ

What is the maximum I²C clock frequency supported by the SI8400AB-B-IS?

The SI8400AB-B-IS supports a maximum I²C clock frequency of 1.7 MHz, as specified in Table 6 of the Skyworks datasheet Rev. 1.6. This enables full-speed I²C operation and compatibility with SMBus 3.0 timing requirements. The device achieves this using optimized RF modulation and low-propagation-delay circuitry, with measured tPHL/tPLH ≤29 ns at 5 V supply.

Does the SI8400AB-B-IS require external pull-up resistors on SDA and SCL lines?

Yes, the SI8400AB-B-IS requires external pull-up resistors on both ASDA/ASCL and BSDA/BSCL lines, as its I²C outputs are open-drain. Typical values range from 1 kΩ to 10 kΩ depending on bus capacitance and speed; Skyworks recommends 4.7 kΩ for 1.7 MHz operation with ≤200 pF total bus capacitance. No internal pull-ups are integrated.

Is the SI8400AB-B-IS pin-compatible with other devices in the Si840x family?

No, the SI8400AB-B-IS is not pin-compatible with Si8402 or Si8405 variants. It uses the 8-pin SOIC-8 narrow-body package with dedicated SDA/SCL bidirectional channels on both sides. Si8402 adds unidirectional channels, and Si8405 uses a 16-pin SOIC package-requiring distinct PCB layouts and routing.

What safety certifications does the SI8400AB-B-IS hold?

The SI8400AB-B-IS is certified to UL 1577 (2500 VRMS), CSA Component Acceptance Notice 5A (IEC 60950-1/61010-1), and VDE IEC 60747-5-2. These cover reinforced insulation up to 300 VRMS working voltage and validate its suitability for industrial and medical equipment requiring regulatory compliance.

How does the SI8400AB-B-IS handle power loss on one side during operation?

When power is lost on one side (e.g., BVDD = 0 V), the SI8400AB-B-IS places the corresponding I²C outputs (BSDA/BSCL) into high-impedance state to prevent bus contention, while maintaining functional isolation. Side A remains operational and can drive its local bus. This behavior is confirmed in Table 12 and Section 3.4 of the datasheet.

SI8400AB-B-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-B-IS FAQ

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

Please submit a Request for Quotation (RFQ) for SI8400AB-B-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-B-IS reliable?

The price and inventory of SI8400AB-B-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-B-IS is usually 5 days.

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

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

Note: Certain payment methods may incur a processing fee.

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

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

Once your SI8400AB-B-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-B-IS?

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

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

All SI8400AB-B-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-B-IS meets industry standards.

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

All SI8400AB-B-IS units undergo pre-shipment inspection (PSI). If there is an issue with SI8400AB-B-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-B-IS part is unused and in its original packaging.

Return procedure for SI8400AB-B-IS:

1.Submit a request within 90 days.

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

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