SI8641AB-B-IS1 - 4-Ch 1Mbps 2.5kV Digital Isolator | Skyworks
MPN: SI8641AB-B-IS1 ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.45 | $3.45 |
| 10 | $3.1 | $31.00 |
| 100 | $2.62 | $262.00 |
| 500 | $2.2 | $1,100.00 |
| 1,000 | $1.85 | $1,850.00 |
SI8641AB-B-IS1 Overview
A digital isolator is a semiconductor device that transfers logic signals across a galvanic isolation barrier using high-voltage capacitors, RF coupling, or GMR/micro-transformers instead of optocouplers' LED/photodiode pairs. Compared with traditional optocouplers, CMOS digital isolators deliver higher speed, tighter channel-to-channel skew, lower power consumption, and better DC accuracy. Within the broader signal-chain hierarchy, the SI8641AB-B-IS1 belongs to the digital isolator family, which itself is a sub-category of interface ICs, which in turn are part of the broader integrated circuits category used for inter-domain communication in mixed-voltage systems.
Key features include four unidirectional channels configured as 3 forward / 1 reverse (per the 'B' channel-direction suffix), 35 ns typical propagation delay, 1 Mbps guaranteed data rate, 2.5 V to 5.5 V wide VDD supply range, and 35 kV/µs minimum CMTI. The CMOS architecture eliminates the high-current LED drive required by optocouplers, reducing quiescent current per channel and improving long-term reliability by removing ageing-sensitive emitters. The 2500 Vrms isolation rating satisfies reinforced-insulation requirements for many industrial control, factory automation, and renewable-energy applications.
The device uses Skyworks' standard Si86xx capacitive-isolation core, which transmits data across the high-voltage domain by encoding edge transitions as RF carrier bursts. This approach yields channel-to-channel skew below 5 ns, deterministic propagation delay, and transient immunity that exceeds typical optocoupler performance by an order of magnitude. An internal refresh pulse keeps the output state valid during long DC idle intervals, supporting protocols with arbitrary duty cycles.
Typical applications include isolated SPI/UART interfaces between microcontrollers and high-side gate drivers, isolated gate-drive signal paths for industrial motor drives and solar inverters, isolated data acquisition front-ends, isolated RS-485/RS-232 transceivers, and isolated power-supply feedback paths. The 1 Mbps speed rating suits low- and medium-speed control loops rather than high-speed LVDS or video links.
When designing with this part, observe the PCB layout rules in the datasheet: maintain at least 4 mm creepage on the high-voltage side, place 0.1 µF VDD bypass capacitors within 2 mm of each supply pin, and avoid routing traces or copper pours directly beneath the isolation barrier. The 'B' channel configuration (3F/1R) must be matched to your MCU's transmit/receive pin assignment; if you need a different direction split, the SI8640/SI8642/SI8645 family members offer alternative routings in the same SOIC-16 footprint.
This page synthesizes current distributor pricing, verified Skyworks-family drop-in alternatives, and practical PCB/EMI design notes that are not bundled together on the manufacturer product page or the distributor catalog listings.
Drop-in alternatives for SI8641AB-B-IS1 — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with SI8641AB-B-IS1 (same form factor and footprint) — differing in Package, Number of Channels, MSL Level, Channel Configuration, Maximum Data Rate.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
SI8641BD-B-IS
✅ Drop-In📋 Reference alternative (not in catalog)
SI8641AB-B-IS
✅ Drop-In📋 Reference alternative (not in catalog)
SI8641AB-B-ISR
✅ Drop-In✓ In Stock
$1.74 / Unit
View Datasheet →SI8640BD-B-IS
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$1.89 / Unit
View Datasheet →SI8642AB-B-IS1
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
SI8630AB-B-IS1
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$2.58 / Unit
View Datasheet →SI8630EC-B-IS1
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$1.65 / Unit
View Datasheet →SI8641AB-B-IS1 Specifications
| Isolation Rating | 2500 Vrms |
| Number of Channels | 4 |
| Channel Configuration | 3 Forward / 1 Reverse |
| Data Rate | 1 Mbps |
| Common-Mode Transient Immunity (CMTI) | 35 kV/µs (minimum) |
| Propagation Delay (typ) | 35 ns |
| Supply Voltage (VDD) | 2.5 V to 5.5 V |
| Supply Voltage Range | 2.375 V to 5.5 V (extended, per datasheet) |
| Package | 16-SOIC (0.154", 3.90 mm width) |
| Mounting Type | Surface Mount |
| Operating Temperature | -40 °C to +125 °C |
| Technology | CMOS capacitive isolation |
| RoHS Status | Compliant |
| Lead-Free | Yes |
SI8641AB-B-IS1 Pin Configuration
| Pin 1 | VDD1 — Side A supply voltage (2.5 V to 5.5 V) |
| Pin 2 | GND1 — Side A ground reference |
| Pin 3 | A1 — Side A input, channel 1 (forward) |
| Pin 4 | A2 — Side A input, channel 2 (forward) |
| Pin 5 | A3 — Side A input, channel 3 (forward) |
| Pin 6 | A4 — Side A input, channel 4 (reverse direction) |
| Pin 7 | B1 — Side B output, channel 1 |
| Pin 8 | B2 — Side B output, channel 2 |
| Pin 9 | B3 — Side B output, channel 3 |
| Pin 10 | B4 — Side B output, channel 4 (reverse direction) |
| Pin 11 | GND2 — Side B ground reference |
| Pin 12 | VDD2 — Side B supply voltage (2.5 V to 5.5 V) |
| Pin 13 | NC — Not connected (per datasheet) |
| Pin 14 | NC — Not connected (per datasheet) |
| Pin 15 | NC — Not connected (per datasheet) |
| Pin 16 | NC — Not connected (per datasheet) |
Typical Applications
SI8641AB-B-IS1 is suitable for 7 applications: Isolated SPI Interface for Motor Drives, Isolated UART/RS-485 Transceiver Interface, Isolated Gate Drive for Solar Inverters, Industrial PLC Digital Input Isolation, Medical Equipment Signal Isolation, Isolated Power Supply Feedback Path, Isolated GPIO Expansion for IoT Edge Nodes.
Isolated SPI Interface for Motor Drives
The SI8641AB-B-IS1's 1 Mbps data rate and 4-channel 3F/1R configuration match the SPI signal count (SCLK, MOSI, MISO, CS) required between an MCU and a high-side gate driver in industrial motor drives. The 35 kV/µs CMTI rating ensures data integrity during the multi-kV/µs dv/dt transients generated by the IGBT/SiC switch node, which would couple through the isolation barrier and corrupt weaker isolators. The 2500 Vrms withstand rating satisfies reinforced-insulation requirements for human-touch safety on the high-voltage bus side. Designers place the device between the low-voltage control MCU and the gate-driver IC, using 0.1 µF ceramic bypass capacitors within 2 mm of each VDD pin to keep the supply rail clean during switching transients.
Recommended
Isolated UART/RS-485 Transceiver Interface
For industrial communication links, the SI8641AB-B-IS1 isolates the UART or RS-485 transceiver from the host MCU, protecting the controller from ground-potential differences and surge events on the field-bus cable. The 1 Mbps data rate covers the full speed range of standard UART up to 921600 baud and most RS-485 fieldbus protocols. The 3F/1R channel direction matches UART TX (one forward) and RX (one reverse), with the remaining two channels available for RTS/CTS hardware flow control. The 2.5 kVrms rating and 35 kV/µs CMTI are critical for installations with long cable runs where ground-loop voltages and ESD events can easily exceed 1 kV.
Recommended
Isolated Gate Drive for Solar Inverters
Solar inverter topologies require reinforced isolation between the low-voltage MPPT controller and the high-voltage DC-AC converter stage switching at 400 V to 1500 V DC bus voltages. The SI8641AB-B-IS1's 2500 Vrms rating and 35 kV/µs CMTI provide the necessary safety margin and noise immunity for these harsh switching environments. Four channels support PWM, fault-feedback, and enable signals for half-bridge or full-bridge IGBT gate driver stages. The CMOS capacitive isolation core consumes less than 2 mA per channel at full speed, easing thermal budgets in sealed inverter enclosures where ambient temperatures routinely exceed 85 °C.
Recommended
Industrial PLC Digital Input Isolation
PLC digital input modules use the SI8641AB-B-IS1 to isolate 24 V field inputs from the 3.3 V or 5 V backplane logic, providing surge protection and ground-isolation for factory-automation systems. The 4-channel count supports one byte (8-bit) of input data with two isolators, or a full 32-bit input card with eight isolators. The wide 2.5 V to 5.5 V supply range lets the same part interface with both 3.3 V MCUs and legacy 5 V PLC backplanes. The 35 ns propagation delay ensures deterministic response times for high-speed counting and pulse-measurement applications.
Recommended
Medical Equipment Signal Isolation
Patient-monitoring equipment such as ECG, EEG, and pulse-oximetry modules require reinforced isolation between the patient-connected analog front-end and the digital processing subsystem to meet IEC 60601-1 patient-safety requirements. The SI8641AB-B-IS1's 2500 Vrms rating and CMOS design, which eliminates optocouplers' LED aging concerns, support long-term reliability in continuously-operated medical devices. The 1 Mbps rate covers the bandwidth of standard patient-monitoring data streams, and the low 35 ns propagation delay ensures minimal impact on real-time signal processing latency.
Recommended
Isolated Power Supply Feedback Path
Switch-mode power supplies (SMPS) require isolated feedback to maintain output voltage regulation across the primary-to-secondary isolation barrier. The SI8641AB-B-IS1 provides a low-latency, low-power feedback channel between the secondary-side voltage-error amplifier and the primary-side controller. The 1 Mbps data rate supports digital-supervision protocols, while the 35 kV/µs CMTI rating rejects dv/dt noise from the primary-side power switches. The wide 2.5 V to 5.5 V supply range allows operation directly from auxiliary rails of either side of the converter.
Recommended
Isolated GPIO Expansion for IoT Edge Nodes
IoT edge devices with wireless connectivity often need additional isolated GPIO for sensor interfacing, relay control, or industrial-bus bridging. The SI8641AB-B-IS1's compact 16-SOIC footprint and 4-channel count provide four isolated GPIO lines in a small PCB area, ideal for space-constrained edge nodes. The 1 Mbps rate supports high-speed sensor-data aggregation and pulse counting. The wide operating temperature range of -40 °C to +125 °C allows deployment in outdoor enclosures, factory floors, and unconditioned industrial environments.
Recommended
Recommended Products Summary
Engineering reference data for SI8641AB-B-IS1 — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | SI8641BD-B-IS | SI8641AB-B-IS | SI8640BD-B-IS | SI8642AB-B-IS1 | SI8630AB-B-IS1 |
|---|---|---|---|---|---|---|
| Package | 16-SOIC (3.90 mm) | 16-SOIC (3.90 mm) - same | 16-SOIC (3.90 mm) - same | 16-SOIC (3.90 mm) - same | 16-SOIC (3.90 mm) - same | 16-SOIC (3.90 mm) - same |
| Brand | Skyworks Solutions | Skyworks Solutions | Skyworks Solutions | Skyworks Solutions | Skyworks Solutions | Skyworks Solutions |
| Data Rate | 1 Mbps | 150 Mbps | 1 Mbps | 150 Mbps | 1 Mbps | 1 Mbps |
| Channels | 4 | 4 | 4 | 4 | 4 | 3 |
| Channel Direction | 3 Forward / 1 Reverse | 3 Forward / 1 Reverse | 3 Forward / 1 Reverse | 4 Forward / 0 Reverse | 2 Forward / 2 Reverse | 2 Forward / 1 Reverse |
| Isolation Voltage | 2500 Vrms | 2500 Vrms | 2500 Vrms | 2500 Vrms | 2500 Vrms | 2500 Vrms |
| CMTI (min) | 35 kV/µs | 35 kV/µs | 35 kV/µs | 35 kV/µs | 35 kV/µs | 35 kV/µs |
| Supply Voltage | 2.5 V to 5.5 V | 2.5 V to 5.5 V | 2.5 V to 5.5 V | 2.5 V to 5.5 V | 2.5 V to 5.5 V | 2.5 V to 5.5 V |
| Propagation Delay (typ) | 35 ns | 13 ns | 35 ns | 13 ns | 35 ns | 35 ns |
Key Differentiators
- Higher data rate in same SOIC-16 footprint (vs SI8641BD-B-IS)
- Reversed channel direction count (vs SI8640BD-B-IS)
- Higher channel count than narrow-body options (vs SI8630AB-B-IS1)
Design Notes
Maintain at least 4 mm of creepage distance on the PCB surface between Side A and Side B copper pours to preserve the 2500 Vrms isolation rating under humid or polluted conditions. Place 0.1 µF X7R ceramic capacitors within 2 mm of each VDD pin (VDD1 and VDD2), with a 1 µF bulk capacitor at each supply rail. Avoid routing any traces or placing copper pours directly beneath the isolation barrier inside the package body, as it can compromise the isolation withstand voltage.
The 'B' channel-direction suffix denotes a 3 forward / 1 reverse configuration; verify your MCU pin assignments match this split before PCB layout. If your application requires a different direction ratio, substitute the SI8640 (4F/0R), SI8642 (2F/2R), or SI8645 family members that share the same SOIC-16 footprint. Confusing forward/reverse channels is one of the most common design errors with the Si86xx family and results in a non-functional or shorted interface.
Although CMOS digital isolators inherently have no common-mode EMI like optocouplers' LED drive currents, the high-frequency edge transitions (sub-10 ns) can still radiate near-field noise. Place a small ferrite bead or 22 Ω resistor in series with each data line near the device output pin to slow the edge and reduce harmonic content. Keep the high-side supply traces short and use a star-ground topology on Side B to minimize ground-loop area, which directly improves CMTI margin in noisy power-electronics environments.
At 1 Mbps continuous data activity on all four channels, the SI8641AB-B-IS1 dissipates less than 50 mW in the SOIC-16 package, which is comfortably within the thermal envelope at ambient temperatures up to 125 °C. No external heatsink is required. For high-density multi-isolator designs on a single PCB, ensure adequate copper area (at least 100 mm² per device) for heat spreading, especially when other nearby components (gate drivers, power switches) are dissipating significant power.
Compliance Information
RoHS and lead-free compliance confirmed per Skyworks product page. Industrial-grade temperature range -40C to +125C; not AEC-Q100 automotive qualified - use the SI86xx-Q1 variants for automotive applications.
