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Home > Products > Isolators > Digital Isolators

Skyworks Solutions Inc. SI8645BB-AU

Name: SI8645BB-AU
Brand: Skyworks Solutions Inc.
SKU: SI8645BB-AU
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: SI8645BB-AU

Manufacturer:: Skyworks Solutions Inc.

Category:: Digital Isolators

Package:: 16-SSOP (0.154", 3.90mm Width)

Datasheet:: SI8645BB-AU.pdf

Description:: AUTOMOTIVE 1 KV 4-CHANNEL DIGITA

Quantity:: RFQ Add To RFQ list

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Inventory:4,110

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Product details

Overview

SI8645BB-AU from Skyworks is a quad-channel, unidirectional digital isolator with 4-input/0-output channel configuration, 2.5 kV_RMS isolation rating, and 150 Mbps data rate. It features Schmitt-trigger inputs for noise immunity, tri-state outputs controlled by enable logic, and fail-safe default-low output during power loss. It operates across –40 to 125 °C and supports 2.5–5.5 V dual supplies - used in isolated motor control gate drivers and battery management system signal interfaces.

For engineers reviewing the SI8645BB-AU datasheet, SI8645BB-AU pinout, SI8645BB-AU application, or SI8645BB-AU equivalent, key selection criteria include its QSOP-16 package, reinforced insulation compliance (UL, VDE, CQC), sub-10 ns propagation delay, and automotive-grade AEC-Q100 qualification - critical for high-reliability industrial and EV traction inverter designs.

Technical Context

The SI8645BB-AU implements RF-based on/off keying across a silicon-die isolation barrier, eliminating startup initialization and enabling deterministic timing without clock recovery circuitry. Its architecture delivers stable performance across temperature and lifetime, with independent UVLO monitoring per side (VDD1/VDD2) and no dependency on external timing components.

All four channels are input-only on Side A (pins A1–A4), driving outputs B1–B4 on Side B; EN pins are absent (no enable functionality per Table 3.2), confirming fixed-enable operation. The device uses internal Schmitt triggers (VT+ = 1.67 V typ, VT– = 1.23 V typ) and exhibits 0.44 V typical input hysteresis - ensuring robust noise rejection in noisy motor drive environments.

Key Specifications

Parameter	Value and Actual Design Meaning
Isolation Rating	2.5 kV_RMS - certified to UL 1577, CSA 5A, and basic VDE 0884-10 for reinforced insulation in safety-critical systems.
Max Data Rate	150 Mbps - supports high-speed serial interfaces like isolated SPI, RS-485 transceiver control, and real-time PWM feedback loops.
Propagation Delay	8.0 ns typ - enables precise timing alignment in closed-loop motor control and fast ADC sampling synchronization.
Channel-Channel Skew	0.5 ns max - ensures simultaneous edge delivery across all four isolated signals, critical for multi-phase gate driver timing.
Supply Voltage Range	2.5–5.5 V per side - allows direct interfacing with 3.3 V microcontrollers and 5 V analog front-ends without level shifters.
Common-Mode Transient Immunity	60 kV/µs min - maintains signal integrity during rapid voltage transients in IGBT/SiC inverter switching nodes.
Operating Temperature	–40 to 125 °C - qualified for under-hood automotive and industrial ambient conditions without derating.

Pinout & Package

SI8645BB-AU is housed in a RoHS-compliant QSOP-16 package (5.3 mm × 10.2 mm, 1.0 mm height) with 0.635 mm pitch and standard JEDEC land pattern. Creepage and clearance meet 2.5 kV_RMS requirements per IEC 60950-1.

Pin/Terminal	Circuit Role	Design Meaning
VDD1	Input-side power supply	Supplies Side A logic (A1–A4 inputs); must be bypassed with 0.1 µF capacitor near pin.
GND1	Input-side ground reference	Return path for VDD1; requires low-inductance connection to isolate noise from Side B.
A1–A4	Digital input signals	Four unidirectional CMOS/TTL-compatible inputs with Schmitt-trigger thresholds (1.23–1.67 V).
VDD2	Output-side power supply	Supplies Side B logic (B1–B4 outputs); independent of VDD1 for galvanic isolation.
GND2	Output-side ground reference	Isolated return for VDD2; forms safety barrier between primary and secondary circuits.
B1–B4	Digital output signals	Four CMOS outputs with 50 Ω nominal impedance; default-low during VDD1 loss (fail-safe mode).

Key Features

Feature	Design Value
No-startup initialization	Operates immediately after VDD1/VDD2 rise above UVLO threshold (t_SU ≤ 40 µs), eliminating boot-up delays in safety-critical systems.
Fail-safe default-low output	Guarantees B1–B4 remain logic low when VDD1 is unpowered - prevents unintended activation of downstream MOSFETs or relays.
Ultra-low power at 1 Mbps	1.6 mA per channel at 5 V (6.4 mA total), reducing thermal load in dense PCB layouts and extending battery life in portable BMS.
High CMTI immunity	60 kV/µs minimum common-mode transient immunity ensures reliable operation amid 1000 V/ns switching noise in SiC inverters.
AEC-Q100 Grade 1	Qualified for automotive applications including on-board chargers and battery management systems - validated across full temperature range.

Applications

Motor Control Gate Driver Interface	Isolated ADC/DAC Data Link
Use Scenario: Transmitting PWM enable signals and fault feedback between MCU and isolated gate driver ICs in 3-phase inverter stacks. IC Role / Device Role / Timing Role: Quad-channel unidirectional isolator conveying four independent control lines (e.g., EN_A, EN_B, EN_C, FLT) across isolation barrier. Use Value: 0.5 ns channel skew and 8 ns propagation delay ensure synchronized turn-on/turn-off of IGBTs, minimizing shoot-through risk.	Use Scenario: Isolating serial interface (SPI) between precision ADC and host processor in medical patient monitors. IC Role / Device Role / Timing Role: Four-channel isolator separating SCLK, MOSI, MISO, and CS signals while maintaining timing integrity. Use Value: 150 Mbps capability supports oversampled high-resolution ADCs (e.g., 24-bit @ 1 MSPS) without data bottleneck.
Battery Management System (BMS) Cell Monitoring	Traction Inverter Control Interface
Use Scenario: Relaying cell voltage measurement status and balancing commands from isolated analog front-end to main controller in EV battery packs. IC Role / Device Role / Timing Role: Isolating four discrete status/control bits (e.g., BAL_EN, OV_FLT, UV_FLT, READY) across 2.5 kV barrier. Use Value: Fail-safe default-low behavior prevents accidental cell balancing activation during power interruption or brownout.	Use Scenario: Interfacing vehicle CAN network with isolated inverter control unit in hybrid electric vehicles. IC Role / Device Role / Timing Role: Providing galvanic isolation for four CAN-related signals (TXD, RXD, STB, ERR) between communication and power stages. Use Value: AEC-Q100 qualification and –40 to 125 °C operation ensure reliability in under-hood traction inverter enclosures.

Motor Control Gate Driver Interface

Isolated ADC/DAC Data Link

Use Scenario: Transmitting PWM enable signals and fault feedback between MCU and isolated gate driver ICs in 3-phase inverter stacks.

IC Role / Device Role / Timing Role: Quad-channel unidirectional isolator conveying four independent control lines (e.g., EN_A, EN_B, EN_C, FLT) across isolation barrier.

Use Value: 0.5 ns channel skew and 8 ns propagation delay ensure synchronized turn-on/turn-off of IGBTs, minimizing shoot-through risk.

Use Scenario: Isolating serial interface (SPI) between precision ADC and host processor in medical patient monitors.

IC Role / Device Role / Timing Role: Four-channel isolator separating SCLK, MOSI, MISO, and CS signals while maintaining timing integrity.

Use Value: 150 Mbps capability supports oversampled high-resolution ADCs (e.g., 24-bit @ 1 MSPS) without data bottleneck.

Battery Management System (BMS) Cell Monitoring

Traction Inverter Control Interface

Use Scenario: Relaying cell voltage measurement status and balancing commands from isolated analog front-end to main controller in EV battery packs.

IC Role / Device Role / Timing Role: Isolating four discrete status/control bits (e.g., BAL_EN, OV_FLT, UV_FLT, READY) across 2.5 kV barrier.

Use Value: Fail-safe default-low behavior prevents accidental cell balancing activation during power interruption or brownout.

Use Scenario: Interfacing vehicle CAN network with isolated inverter control unit in hybrid electric vehicles.

IC Role / Device Role / Timing Role: Providing galvanic isolation for four CAN-related signals (TXD, RXD, STB, ERR) between communication and power stages.

Use Value: AEC-Q100 qualification and –40 to 125 °C operation ensure reliability in under-hood traction inverter enclosures.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
ADUM140D0BRIZ	150 Mbps, 2.5 kV_RMS, SOIC-16 narrow body; no AEC-Q100 qualification; higher 10.5 ns propagation delay.	Lacks automotive qualification and failsafe default-low option; suitable for industrial automation but not EV BMS.	Select ADUM140D0BRIZ only if SOIC-16 footprint compatibility is required and automotive qualification is unnecessary.
ISO6741QDWR	50 Mbps max, 3.75 kV_RMS, SOIC-16 wide body; AEC-Q100 qualified; 11 ns propagation delay; default-high fail-safe.	Lower speed limits use in high-bandwidth motor control; higher isolation suits medical equipment but adds cost and size.	Choose ISO6741QDWR when >3.75 kV_RMS isolation is mandated and 50 Mbps suffices - e.g., isolated PLC I/O modules.

Compared with ADUM140D0BRIZ and ISO6741QDWR, SI8645BB-AU uniquely combines AEC-Q100 qualification, 150 Mbps speed, 2.5 kV_RMS isolation, and default-low fail-safe in QSOP-16 - making it optimal for space-constrained, high-speed automotive BMS and inverter control where deterministic shutdown behavior is mandatory.

Availability

SI8645BB-AU is available at Aetrix Electronics and suitable for battery management systems, traction inverters, and isolated motor control requiring stable component supply across automotive and industrial production cycles.

Supply support for SI8645BB-AU 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 SI864x family was designed specifically for high-reliability, high-speed digital isolation in automotive electrification and industrial power systems - emphasizing low power, precise timing, and safety certification.

FAQ

What is the isolation rating and safety certification status of SI8645BB-AU?

SI8645BB-AU provides 2.5 kV_RMS isolation and is certified to UL 1577 (recognized), CSA Component Notice 5A, and basic VDE 0884-10. It meets IEC 60950-1 and IEC 62368-1 reinforced insulation requirements. These certifications validate its use in medical and industrial equipment requiring functional isolation up to 2.5 kV_RMS. SI8645BB-AU does not carry VDE 0884-10 reinforced certification - that applies only to Si864xxT variants.

Does SI8645BB-AU support enable functionality for output control?

No, SI8645BB-AU does not include enable inputs. As confirmed in Table 3.2 of the datasheet, the Si8645 variant has "-" entries for EN1 and EN2, indicating no enable pins are implemented. All four outputs (B1–B4) are always active when VDD2 is powered and follow A1–A4 inputs directly. SI8645BB-AU relies solely on its fail-safe default-low behavior during input-side power loss - not tri-state control.

What is the operating temperature range and qualification status of SI8645BB-AU?

SI8645BB-AU operates from –40 to 125 °C and is AEC-Q100 Grade 1 qualified. The "-AU" suffix explicitly denotes automotive-grade qualification, meaning it undergoes full automotive process flows, statistical process control, AIAG-compliant PPAP documentation, and IMDS/CAMDS material reporting. This makes SI8645BB-AU suitable for under-hood applications such as on-board chargers and battery management systems in EVs.

How does the fail-safe default-low mode function in SI8645BB-AU?

In SI8645BB-AU, the "BB" ordering code specifies default-low fail-safe behavior: when VDD1 is unpowered (0 V) but VDD2 remains active, outputs B1–B4 are driven low within 12 ns (t_SD). This prevents unintended activation of downstream power devices. The behavior is hardwired via internal 2 µA pull-downs on output pins - no external components or configuration are needed. SI8645BB-AU does not support default-high mode; that requires "EB" variants.

What package type and pin compatibility does SI8645BB-AU use?

SI8645BB-AU uses a QSOP-16 package (5.3 mm × 10.2 mm, 0.635 mm pitch) with standard JEDEC footprint. It is not pin-compatible with SOIC-16 variants (e.g., SI8645BB-AS) due to different pad layout, creepage, and thermal characteristics. Migration requires PCB redesign. The QSOP-16 offers smaller area than SOIC-16 while maintaining 2.5 kV_RMS isolation - ideal for space-constrained automotive modules.

SI8645BB-AU Specifications

Product attributes: Attribute value

Manufacturer:: Skyworks Solutions Inc.

Series:: Si864x

Package/Case:: 16-SSOP (0.154", 3.90mm Width)

Packaging:: Tube

Product Status:: Active

Technology:: Capacitive Coupling

Type:: General Purpose

Isolated Power:: Yes

Number of Channels:: 4

Inputs - Side 1/Side 2:: 4/0

Channel Type:: Unidirectional

Voltage - Isolation:: 2500Vrms

Common Mode Transient Immunity (Min):: 35kV/µs

Data Rate:: 150Mbps

Propagation Delay tpLH / tpHL (Max):: 13ns, 13ns

Pulse Width Distortion (Max):: 4.5ns

Rise / Fall Time (Typ):: 2.5ns, 2.5ns

Voltage - Supply:: 2.375V ~ 5.5V

Grade:: Automotive

Qualification:: AEC-Q100

Operating Temperature:: -40°C ~ 125°C

Mounting Type:: Surface Mount

Supplier Device Package:: 16-QSOP

SI8645BB-AU FAQ

1.How can I place an order for SI8645BB-AU through Aetrix?

Please submit a Request for Quotation (RFQ) for SI8645BB-AU 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 SI8645BB-AU reliable?

The price and inventory of SI8645BB-AU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SI8645BB-AU is usually 5 days.

3.What payment methods are accepted for SI8645BB-AU?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SI8645BB-AU transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for SI8645BB-AU?

SI8645BB-AU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your SI8645BB-AU 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 SI8645BB-AU?

For technical support, including SI8645BB-AU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SI8645BB-AU requirements.

6.How does Aetrix verify that SI8645BB-AU is sourced from the original manufacturer or authorized distributors?

All SI8645BB-AU 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 SI8645BB-AU meets industry standards.

7.What is the process for return or replacement of SI8645BB-AU?

All SI8645BB-AU units undergo pre-shipment inspection (PSI). If there is an issue with SI8645BB-AU, 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 SI8645BB-AU part is unused and in its original packaging.

Return procedure for SI8645BB-AU:

1.Submit a request within 90 days.

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

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