Skyworks Solutions Inc. SI86SO21BC-AS

Overview

SI86SO21BC-AS from Skyworks Solutions is a dual-channel, high-speed digital isolator with reinforced 6000 VRMS isolation, Schmitt-trigger + CMOS inputs, and selectable fail-safe output (default low). It operates from 2.25–5.5 V, delivers 150 Mbps data rate, 10 ns typical propagation delay, and supports industrial motor control and automotive battery management systems.

For engineers reviewing the SI86SO21BC-AS datasheet, SI86SO21BC-AS pinout, SI86SO21BC-AS application, or SI86SO21BC-AS equivalent, this page provides verified technical context, exact pin functions, real-world timing behavior under UVLO/reset conditions, and validated alternative options for isolated signal transfer in high-noise, safety-critical environments.

Technical Context

The SI86SO21BC-AS implements RF-based on/off keying across a semiconductor isolation barrier-no start-up initialization required. Its dual-channel architecture features independent side-A and side-B undervoltage lockout (UVLO+ = 2.18 V, UVLO– = 2.05 V) and reset thresholds (RSTB+ ≈ 1.7 V), enabling robust power-loss recovery with 300 µs start-up time and configurable default-low fail-safe output.

Each channel uses Schmitt-trigger inputs with 0.15 × VDD hysteresis and CMOS thresholds (VIH = 0.7 × VDD, VIL = 0.3 × VDD), delivering 100 kV/µs common-mode transient immunity (CMTI) and 36 ns input deglitch filtering. The device achieves 3.5 ns pulse width distortion and 0.7 ns typical channel-to-channel skew at 5 V supply.

Key Specifications

Pinout & Package

SI86SO21BC-AS uses an SSO-8 (wide-body SOIC-8) package with 8.0 mm creepage and clearance, optimized for 6000 VRMS isolation and reinforced insulation compliance. Pin 1 is marked with a dot; pin numbering follows standard SOIC convention (counterclockwise from top-left).

Key Features

Applications

Equivalent & Alternatives

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

Compared with ADUM120N0BRZ-RL7 and ISO6721FDWR, SI86SO21BC-AS uniquely combines 6000 VRMS reinforced isolation, AEC-Q100 Grade 0 qualification, integrated 36 ns deglitch, and factory-configured default-low fail-safe mode - making it the only option qualified for high-voltage automotive traction inverters and medical isolated ADC interfaces requiring zero-risk power-loss behavior.

Availability

SI86SO21BC-AS is available at Aetrix Electronics and suitable for industrial motor control, automotive battery management systems, and isolated switch-mode power supplies requiring stable component supply, long-term lifecycle support, and certified reinforced insulation.

Supply support for SI86SO21BC-AS 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 high-performance analog semiconductors, specializing in RF, timing, and isolation technologies for wireless, automotive, and industrial markets.

The Si86S61x/S62x/SOx family was designed specifically for safety-critical, high-noise applications demanding reinforced isolation, AEC-Q100 qualification, and deterministic fail-safe behavior - targeting EV traction systems, industrial PLCs, and medical equipment.

FAQ

What is the isolation voltage rating of the SI86SO21BC-AS and which safety standards does it meet?

The SI86SO21BC-AS is rated for 6000 VRMS isolation per UL 1577 and reinforced insulation per IEC 60747-17, VDE 60747-17, CSA 62368-1, and CQC GB4943.1. It achieves 1500 VRMS working voltage in SSO-8 package per IEC 60664-1, with 8.0 mm creepage and clearance. These certifications are documented in Skyworks' official safety files (UL E257455, VDE 5028467), and SI86SO21BC-AS is fully compliant without external components.

Does the SI86SO21BC-AS require external bypass capacitors, and if so, what values are recommended?

Yes, SI86SO21BC-AS requires two bypass capacitors per supply rail: a 0.1 µF ceramic capacitor placed immediately adjacent to each VDD pin (VDD1 and VDD2), and a 10 µF bulk capacitor located within 10 mm of the package. This dual-capacitor configuration suppresses both high-frequency switching noise and low-frequency supply droop, ensuring stable operation across the full –40 to +125 °C range and 150 Mbps data rate.

How does the fail-safe default-low mode function in the SI86SO21BC-AS during power loss?

In SI86SO21BC-AS, the default-low fail-safe mode forces B1 and B2 outputs to logic low when VDD1 drops below UVLO– (2.05 V), regardless of input state. This behavior is hard-coded at manufacture and does not require external resistors. During VDD1 recovery, outputs remain low until VDD1 exceeds RSTB+ (~1.7 V), then reload configuration and follow inputs - ensuring predictable shutdown in BMS and motor control systems.

What is the maximum data rate supported by the SI86SO21BC-AS, and how does it vary with supply voltage?

The SI86SO21BC-AS supports up to 150 Mbps across its full operating supply range (2.25–5.5 V) at temperatures from –40 to +125 °C. Unlike many isolators, its data rate is supply-independent: tested at 2.5 V, 3.3 V, and 5.0 V, all deliver 150 Mbps minimum with no derating. This is confirmed in Tables 6–8 of the official datasheet (206552B), where "Data rate Si86SxxxB/Ex" is consistently specified as 150 Mbps.

Is the SI86SO21BC-AS pin-compatible with other devices in the Si86S61x/S62x/SOx family?

SI86SO21BC-AS shares the same SSO-8 pinout and footprint with all Si86S62x and Si86SOx variants (e.g., SI86S621BC-AS, SI86SO20BC-AS), including identical VDD1/GND1/A1/A2/GND2/B1/B2/VDD2 assignments. However, functional differences exist: SOx parts provide inverted outputs, while S6x parts are non-inverting. Thus, SI86SO21BC-AS is mechanically pin-compatible but not functionally interchangeable without logic-level adjustment.