Skyworks Solutions Inc. SI8635BB-B-IS

Overview

SI8635BB-B-IS from Skyworks is a triple-channel, unidirectional digital isolator with 3 input channels on VDD1 side and 0 on VDD2 side, rated for 2.5 kVRMS isolation in a wide-body SOIC-16 package. It supports up to 150 Mbps data rate, exhibits ≤13 ns propagation delay, ≤4.5 ns pulse width distortion, and operates across –40 to +125 °C with 2.5–5.5 V supply per side. It is used in isolated motor control gate drivers where high-speed, low-power signal integrity across reinforced insulation barriers is critical.

For engineers reviewing the SI8635BB-B-IS datasheet, SI8635BB-B-IS pinout, SI8635BB-B-IS application, or SI8635BB-B-IS equivalent, key selection criteria include confirmed 3-channel unidirectional topology, 2.5 kVRMS wide-body SOIC-16 isolation rating, fail-safe default-low output behavior, sub-13 ns propagation delay at 150 Mbps, and AEC-Q100-compatibility readiness for industrial power systems.

Technical Context

The SI8635BB-B-IS implements RF-based on/off keying across a semiconductor isolation barrier-eliminating startup initialization and enabling robust noise immunity without optical degradation. Its architecture delivers precise timing with ≤2.5 ns channel-to-channel skew and ≤4.5 ns propagation delay skew across temperature and voltage.

All three channels are input-only on the VDD1 side (A1–A3), driving outputs B1–B3 on the VDD2 side; no enable pins are present (EN1/EN2 = NC), confirming fixed-enable operation. Schmitt-trigger inputs provide ≥0.44 V hysteresis, and undervoltage lockout (UVLO) ensures clean state transitions during power ramp-up with ≤40 µs start-up time.

Key Specifications

Pinout & Package

SI8635BB-B-IS is housed in a RoHS-compliant wide-body SOIC-16 package (7.5 mm creepage/clearance), supporting reinforced insulation per IEC 60950-1 and UL 1577. Pin assignments follow standard Si863x layout with dedicated VDD1/GND1 and VDD2/GND2 pairs, and no enable pins.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ADUM130N0BRZ and ISO6731FDWR, SI8635BB-B-IS uniquely combines 150 Mbps speed, 2.5 kVRMS wide-body isolation, and factory-configured default-low output in a single industrial-grade device-enabling compact, high-fidelity isolation for next-generation motor drives without layout or firmware adaptation.

Availability

SI8635BB-B-IS is available at Aetrix Electronics and suitable for industrial motor control, isolated power supplies, and battery management systems requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.

Supply support for SI8635BB-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 semiconductor company specializing in analog and mixed-signal connectivity solutions, with leadership in RF, timing, and isolation technologies.

The Si863x family was designed specifically for high-reliability industrial and automotive isolation applications demanding ultra-low power, precise timing, and reinforced safety certification-targeting motor drives, power converters, and BMS interfaces.

FAQ

What is the isolation rating and certification status of SI8635BB-B-IS?

SI8635BB-B-IS is certified for 2.5 kVRMS isolation per UL 1577 and CSA Component Acceptance Notice 5A, and complies with IEC 60950-1 reinforced insulation requirements. It carries VDE and CQC approvals and is built using Skyworks' industrial-grade manufacturing flow. The SI8635BB-B-IS device does not carry VDE 0884-10 certification, which applies only to Si862xxT and Si863xT variants.

Does SI8635BB-B-IS support bidirectional communication or enable control?

No, SI8635BB-B-IS provides three unidirectional channels (A1–A3 → B1–B3) with no enable pins (EN1/EN2 = NC per datasheet Table 3.2). It lacks reverse-path capability and cannot be disabled into high-impedance state. All outputs are always active and follow inputs when both VDD1 and VDD2 are powered. This fixed-enable behavior is inherent to the SI8635BB-B-IS part number.

What is the default output state of SI8635BB-B-IS during input-side power loss?

SI8635BB-B-IS is configured for default-low fail-safe operation: when VDD1 is unpowered but VDD2 remains active, outputs B1–B3 drive logic low within ≤12 ns (tSD parameter). This behavior is factory-set per ordering code "BB" and "-B" suffix, and requires no external components-ensuring predictable shutdown of downstream power stages.

Can SI8635BB-B-IS operate with mixed supply voltages, such as 3.3 V on VDD1 and 5 V on VDD2?

Yes, SI8635BB-B-IS supports independent 2.5–5.5 V supplies on each side. It is fully specified for 3.3 V on VDD1 and 5 V on VDD2 (or vice versa), with verified timing, CMTI, and logic thresholds across all combinations. Input thresholds (VT+ = 1.67 V typ, VT– = 1.23 V typ) ensure reliable recognition of 3.3 V logic levels when VDD1 = 3.3 V, and output VOH/VOL specs guarantee 5 V-compatible drive strength when VDD2 = 5 V.

How does the RF-based isolation architecture of SI8635BB-B-IS differ from optocouplers or capacitive isolators?

SI8635BB-B-IS uses on/off keying of an internal RF carrier across a silicon dioxide barrier-delivering faster propagation (<13 ns vs. >50 ns for optocouplers), no LED aging, no startup initialization, and superior CMTI (50 kV/µs vs. ~20 kV/µs for capacitive isolators). Unlike optocouplers, it requires no current-limiting resistors; unlike some capacitive isolators, it avoids high-frequency EMI concerns due to its narrowband modulation scheme.