Skyworks Solutions Inc. SI8400AA-B-IS

Overview

SI8400AA-B-IS from Skyworks Solutions is a bidirectional I²C isolator with two galvanically isolated, open-drain SDA and SCL channels, rated for 2500 VRMS isolation, operating from 3.0–5.5 V over –40 to +125 °C, and supporting I²C clock rates up to 1.7 MHz in industrial motor control and hot-swap power systems.

For engineers reviewing the SI8400AA-B-IS datasheet, SI8400AA-B-IS pinout, SI8400AA-B-IS application, or SI8400AA-B-IS equivalent, this device delivers verified bidirectional I²C channel isolation with 35 mA sink capability per channel, sub-30 ns propagation delay at 5 V, and UL/CSA/VDE safety certification - critical for isolated SMBus communication in high-noise, high-reliability embedded systems.

Technical Context

The SI8400AA-B-IS implements RF-based on-off keying across a semiconductor isolation barrier, eliminating startup initialization and enabling robust noise immunity (25 kV/µs CMTI) without optical degradation. Its dual bidirectional I²C channels operate independently with side-specific under-voltage lockout (UVLO+ = 2.3 V, hysteresis = 75 mV), ensuring fault-tolerant behavior during asymmetric power sequencing.

Each I²C channel features matched logic thresholds (Side A: VT = 550–780 mV, VOL ≤ 910 mV @ 3 mA; Side B: VIH ≥ 2.0 V, VOL ≤ 400 mV @ 35 mA), enabling interoperability with standard I²C masters/slaves while maintaining latch-up margin via controlled ΔV (I²CΔV ≥ 125 mV). No external pull-ups are required on the isolated side for compliant bus operation.

Key Specifications

Pinout & Package

SI8400AA-B-IS is housed in an 8-pin narrow-body SOIC package (SOIC-8 NB) with 4.9 mm creepage/clearance, RoHS-compliant matte tin lead finish, and 140 °C/W junction-to-air thermal resistance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ADUM1250ARZ and ISO1540DR, SI8400AA-B-IS provides superior I²C timing headroom (1.7 MHz), tighter propagation delay matching (±5 ns skew), and proven hot-swap resilience - making it preferred for high-reliability industrial and PoE applications demanding full-speed bus transparency and long-term stability.

Availability

SI8400AA-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-lifecycle support, and certified 2500 VRMS isolation.

Supply support for SI8400AA-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, and industrial markets.

The Si840x family was designed specifically to replace optocouplers in I²C/SMBus isolation applications, delivering higher speed, lower power, and longer reliability with RF-based galvanic isolation in compact SOIC packages.

FAQ

What is the maximum I²C clock frequency supported by the SI8400AA-B-IS?

The SI8400AA-B-IS supports I²C clock frequencies up to 1.7 MHz, verified across its full operating temperature range (–40 to +125 °C) and supply range (3.0–5.5 V). This enables compliance with Fast-mode Plus (Fm+) I²C specifications and accommodates timing margins for bus capacitance up to 400 pF when using standard 1–4.7 kΩ pull-up resistors. The SI8400AA-B-IS achieves this with sub-30 ns propagation delay and <15 ns pulse width distortion.

Does the SI8400AA-B-IS require external pull-up resistors on both sides of the I²C bus?

Yes, the SI8400AA-B-IS requires external pull-up resistors on both the Side A (SDAA/SCLA) and Side B (SDAB/SCLB) I²C lines. Its open-drain outputs do not include internal pull-ups. Typical values range from 1 kΩ (for 1.7 MHz operation with low bus capacitance) to 10 kΩ (for 100 kHz with high capacitance). Pull-ups must connect to their respective local VDD rails (VDDA or VDDB), not across the isolation barrier.

How does the SI8400AA-B-IS handle power loss on one side during operation?

When power is lost on either side (VDDA or VDDB drops below UVLO– threshold), the SI8400AA-B-IS places the corresponding I²C outputs into high-impedance (Hi-Z) state to prevent bus contention. Side-specific UVLO circuitry ensures outputs remain low until both supplies exceed 2.3 V, and start-up time is guaranteed ≤40 µs. This behavior is explicitly validated in Table 12 of the datasheet for hot-swap and partial-failure scenarios.

What safety certifications apply to the SI8400AA-B-IS?

The SI8400AA-B-IS carries UL 1577 (2500 VRMS, File E257455), CSA Component Acceptance Notice 5A (IEC 60950-1/61010-1), and VDE 0884-2 (IEC 60747-5-2) certifications. These cover reinforced insulation up to 300 VRMS working voltage (CSA/UL) and 560 Vpeak (VDE), with production-tested isolation of 3000 VRMS for 1 second. Certification applies to the SOIC-8 narrow-body package variant.

Can the SI8400AA-B-IS be used with 1.8 V I²C devices?

No, the SI8400AA-B-IS is not compatible with 1.8 V I²C interfaces. Its minimum supply voltage is 3.0 V, and its logic thresholds are specified for 3.0–5.5 V operation: Side A input threshold is 550–780 mV, Side B requires VIH ≥ 2.0 V. Connecting to a 1.8 V system would violate input voltage limits (VI < 0.45 V min) and risk unreliable logic recognition. For 1.8 V systems, consider the Si86xx family or level-shifting solutions external to the isolator.