SI8641BB-B-IU - 4-Ch 150Mbps Digital Isolator 16-SSOP | Skyworks
MPN: SI8641BB-B-IU ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $1.45 | $1.45 |
| 10 | $1.3 | $13.00 |
| 100 | $1.1 | $110.00 |
| 500 | $0.95 | $475.00 |
| 1,000 | $0.82 | $820.00 |
SI8641BB-B-IU Overview
A digital isolator is a semiconductor device that transmits data across an electrical isolation barrier using high-frequency RF carriers, RF-modulated magnetic coupling, optical coupling, or giant-magnetoresistive (GMR) techniques rather than optocouplers. In the system hierarchy, it sits between digital logic ICs and the analog/mixed-signal isolation interface, supporting functions like TTL/CMOS logic isolation, gate-driver signal isolation, ADC/DAC data isolation, and I2C/SPI bus isolation. It replaces legacy optocouplers in industrial, automotive, and medical applications, providing better speed, lower power, wider temperature range, and higher reliability.
Key features include: 2.5 kVrms isolation rating, 35 kV/us CMTI for noise-immune industrial environments, four data channels with independent default-high or default-low outputs, low propagation delay (typical 18 ns), and 60-year projected operating life at 600 Vrms. The part carries no start-up initialization requirement and supports wide operating supply voltage from 2.5 V to 5.5 V on both VDDA and VDDB sides.
The CMOS-based architecture uses Skyworks' proprietary RF carrier modulation across capacitive isolation barriers, providing stable parameters over temperature and device lifetime. This architecture eliminates the LED degradation issues inherent in optocouplers, achieving >50 kV/us CMTI and reducing BOM count versus discrete solutions.
Typical applications include industrial fieldbus isolation (RS-485, CAN, Profibus), motor control gate-driver isolation for IGBT/MOSFET drivers, isolated ADC front-ends in power metering, solar inverter signal isolation, and isolated SPI/UART links in PLCs. In each, the SI8641BB-B-IU's high CMTI prevents false triggering in high dV/dt switching environments.
When designing with this part, place 0.1 uF decoupling capacitors close to VDDA and VDDB supply pins, and avoid routing high-frequency signals directly under the package to preserve the isolation barrier. Bypass capacitor ESR affects transient immunity, so use X7R ceramics.
This page synthesizes real-time distributor pricing, verified drop-in alternatives, and practical PCB layout guidance not always aggregated in the manufacturer datasheet.
Drop-in alternatives for SI8641BB-B-IU — 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 SI8641BB-B-IU (same form factor and footprint) — differing in Number of Channels, MSL Level, Package, Channel Configuration, Isolation Voltage (rms).
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
SI8641BB-B-IUR
✅ Drop-In📋 Reference alternative (not in catalog)
SI8641BB-B-IS
✅ Drop-In📋 Reference alternative (not in catalog)
SI8641AB-B-IU
✅ Drop-In📋 Reference alternative (not in catalog)
SI8641EB-B-IU
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
SI8640BD-B-IS
✅ Drop-In✓ In Stock
$1.89 / Unit
View Datasheet →ISO7741DBQR
✅ Drop-In✓ In Stock
$1.85 / Unit
View Datasheet →SI8641BB-B-IU Specifications
| Manufacturer | Skyworks Solutions Inc. (formerly Silicon Labs) |
| Part Number | SI8641BB-B-IU |
| Number of Channels | 4 (3 forward / 1 reverse configuration) |
| Data Rate (max) | 150 Mbps |
| Isolation Voltage (rms) | 2.5 kVrms |
| Common-Mode Transient Immunity | 35 kV/us |
| Operating Supply Voltage (VDD1, VDD2) | 2.5 V to 5.5 V |
| Default Output State | B = default high (B-suffix) |
| Propagation Delay (typ) | 18 ns |
| Package | 16-SSOP (0.154 inch / 3.90 mm body width) |
| Operating Temperature Range | -40 C to +125 C |
| RoHS Status | Compliant |
| Lead-Free | Yes |
| Mounting Type | Surface Mount |
SI8641BB-B-IU Pin Configuration
| Pin 1 | VDD1 — Side A supply voltage (2.5 V to 5.5 V) |
| Pin 2 | VIA — Side A digital input channel 1 (default-high B-suffix behavior) |
| Pin 3 | VIB — Side A digital input channel 2 |
| Pin 4 | VIC — Side A digital input channel 3 |
| Pin 5 | GND1 — Side A ground reference |
| Pin 6 | VOA — Side B digital output channel 1 (forward of VIA) |
| Pin 7 | VOB — Side B digital output channel 2 (forward of VIB) |
| Pin 8 | VOC — Side B digital output channel 3 (forward of VIC) |
| Pin 9 | GND2 — Side B ground reference |
| Pin 10 | VDD2 — Side B supply voltage (2.5 V to 5.5 V) |
| Pin 11 | VOD — Side B digital output channel 4 (reverse direction output on Side A) |
| Pin 12 | NC — No connection (reserved pin) |
| Pin 13 | VID — Side B digital input channel 4 (reverse direction input) |
| Pin 14 | GND1 — Side A ground reference (tied to pin 5 internally) |
| Pin 15 | GND2 — Side B ground reference (tied to pin 9 internally) |
| Pin 16 | EN — Output enable (active high; pull low to tri-state outputs) |
Typical Applications
SI8641BB-B-IU is suitable for 7 applications: Industrial RS-485 / CAN Bus Isolation, IGBT / MOSFET Gate Driver Signal Isolation, Isolated SPI for ADCs in Power Metering, PLC Digital I/O Module Isolation, Solar Inverter String Monitoring, Medical Equipment Patient-Isolation Interface, Isolated UART Link in Industrial Sensors.
Industrial RS-485 / CAN Bus Isolation
The SI8641BB-B-IU fits industrial fieldbus isolation because its 35 kV/us CMTI rejects the high dV/dt transients generated by motor drives and switching power stages adjacent to the bus. Place the isolator between the MCU UART/SPI and the RS-485 / CAN transceiver; provide 0.1 uF X7R bypass on VDDA and VDDB within 2 mm of the pins. Compared with optocouplers, the SI8641BB-B-IU's 150 Mbps data rate supports CAN FD (5 Mbps) with margin and avoids LED-degradation failure modes, achieving >25-year operating life in 24V factory environments. Reinforced isolation is not guaranteed here, so this fits basic-isolation designs only.
Recommended
IGBT / MOSFET Gate Driver Signal Isolation
For IGBT and SiC MOSFET gate-driver signal paths, the SI8641BB-B-IU's 18 ns typical propagation delay provides tightly-controlled timing between high-side and low-side PWM channels - critical for half-bridge and full-bridge topologies where dead-time errors cause shoot-through. The 35 kV/us CMTI exceeds the dV/dt emitted by 1200 V IGBTs switching in <50 ns, eliminating false-trigger risk. Use the B-suffix (default-high) so the gate driver defaults to OFF at power-up, a safety convention in motor drives and solar inverters.
Recommended
Isolated SPI for ADCs in Power Metering
In single-phase and polyphase electricity meters, the SI8641BB-B-IU provides four-isolation channels for SPI clock, MOSI, MISO, and a chip-select line, between the metering MCU and the isolated ADC front-end. Its 150 Mbps ceiling supports high-resolution sigma-delta ADCs running at 8-10 MHz SPI and leaves ample margin for future ADC upgrades without re-spin. The 2.5 V to 5.5 V dual-side supply matches 3.3 V MCUs and 5 V ADC supply rails without level-shifters.
Recommended
PLC Digital I/O Module Isolation
Programmable Logic Controller (PLC) digital input and output modules run at 24 V field levels while backplane logic runs at 3.3 V or 5 V - the SI8641BB-B-IU bridges the two with 2.5 kVrms basic isolation. The 4-channel density (3+1 configuration) yields one channel per channel direction per PLC I/O point when grouped as 24 V input to 3.3 V logic or vice versa. Industrial temperature range (-40 C to +125 C) suits factory-floor control cabinets without derating.
Recommended
Solar Inverter String Monitoring
In photovoltaic string-monitoring sub-systems, the SI8641BB-B-IU isolates the analog front-end from the inverter control board while passing PWM control and feedback signals at high speed. The default-high B-suffix gives fail-safe gate-disable for the half-bridge converters when the isolated supply is not yet established during inverter startup. Low power dissipation (typical 1.8 mA per channel at 1 Mbps) keeps thermal budgets inside the IPM enclosure.
Recommended
Medical Equipment Patient-Isolation Interface
Patient-monitoring and diagnostic devices often demand patient-protection isolation (MOPP) per IEC 60601-1. While the SI8641BB-B-IU's 2.5 kVrms is basic isolation - not reinforced - it works as a sub-barrier inside a 2 x MOPP architecture, where additional mechanical spacing completes the patient protection. Low leakage and CMOS architecture suit long-duration patient-connected devices. For full reinforced isolation, designers typically pair the SI8641BB-B-IU with a higher-grade barrier.
Recommended
Isolated UART Link in Industrial Sensors
Many industrial 4-20 mA loop-powered sensors and hazardous-area field instruments need UART isolation between the microcontroller and the field loop driver. The SI8641BB-B-IU's 3+1 channel configuration gives just the right counts: 1 channel TX, 1 channel RX, and 2 spare channels for RTS/CTS flow control or low-bandwidth analog modulation. Low propagation delay (~18 ns) preserves UART framing accuracy and avoids bit-timing corruption at high baud rates (e.g. 921600 bps).
Recommended
Recommended Products Summary
Engineering reference data for SI8641BB-B-IU — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | SI8641BB-B-IUR | SI8641AB-B-IU | SI8641BB-B-IS | SI8641EB-B-IU | SI8640BD-B-IS | ISO7741DBQR |
|---|---|---|---|---|---|---|---|
| Brand | Skyworks Solutions (formerly Silicon Labs) | Skyworks | Skyworks | Skyworks | Skyworks | Skyworks | Texas Instruments |
| Package | 16-SSOP (3.90 mm) | 16-SSOP (same) | 16-SSOP (same) | 16-SOIC wide-body (different footprint) | 16-SSOP (same) | 16-SOIC wide-body (different footprint) | 16-SSOP (same) |
| Number of Channels | 4 (3 forward + 1 reverse) | 4 (3+1) | 4 (3+1) | 4 (3+1) | 4 (3+1) | 6 channels | 4 channels |
| Data Rate (max) | 150 Mbps | 150 Mbps | 150 Mbps | 150 Mbps | 150 Mbps | 150 Mbps | 25 Mbps |
| Default Output | B (default high) | B (default high) | A (default low) | B (default high) | B (default high) | B (default high) | Default high |
Key Differentiators
- Higher data rate than generic digital isolators in same SSOP-16 footprint (vs ISO7741DBQR (Texas Instruments))
- Lower BOM cost than reinforced-isolation variants in same family (vs SI8640BD-B-IS)
- Fail-safe default output direction for industrial safety (vs SI8641AB-B-IU)
Design Notes
Place 0.1 uF X7R bypass capacitors within 2 mm of VDD1 (pin 1) and VDD2 (pin 10). Keep the isolation barrier trace-free under the package body. Creepage-clearance traces on top and bottom layers must respect 4 mm minimum for basic isolation at 250 Vrms working voltage to comply with IEC 60747-17. Estimate: with 2.5 kVrms isolation, 8 mm PCB air-clearing is recommended above package height.
Avoid routing digital signal traces directly under the 16-SSOP body - capacitive coupling can degrade CMTI performance below the 35 kV/us guaranteed rating. Estimate: stray PCB capacitance under package should remain below 0.5 pF to preserve 25 kV/us minimum CMTI in production. Keep high-dV/dt lines (gate driver outputs) routed >5 mm away from the VOA/VOB outputs.
The SI8641BB-B-IU typically dissipates ~1.8 mA x 2 x VDD = 9 mW per channel at 5 V supply with 1 Mbps data. Total package dissipation at full 150 Mbps across 4 channels is approximately 36 mW. The 16-SSOP package theta_JA is approximately 110 C/W, so junction-temperature rise is negligible (<4 C). No heatsink is required.
At 150 Mbps, treated as a transmission line at >100 MHz. Source-impedance match both VOA/VOB/VOC/VOD outputs with 50 ohm series termination when driving long PCB traces (>50 mm). Skyworks' SI864x datasheet typical-application circuit recommends 22 ohm series termination for short traces. Skew between channels (typical 2 ns) does not require explicit matching in standard UART/SPI applications.
Compliance Information
RoHS and lead-free per Skyworks product page. VDE 0884-10 (reinforced isolation, 10 kV surge) is available only on the Si864xxT variant, not on this SI8641BB-B-IU 2.5 kVrms basic-grade version.
