SI8422BB-D-IS - 2.5 kV 2-Channel Digital Isolator | Skyworks
MPN: SI8422BB-D-IS ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.85 | $2.85 |
| 10 | $2.58 | $25.80 |
| 100 | $2.18 | $218.00 |
| 500 | $1.84 | $920.00 |
| 1,000 | $1.52 | $1,520.00 |
SI8422BB-D-IS Overview
What is a digital isolator? A digital isolator is a semiconductor device that transfers logic-level signals across an galvanically isolated barrier using high-frequency RF coupling, capacitive coupling, or giant-magnetoresistance (GMR), replacing legacy optocouplers. The Si84xx family belongs to the digital isolator category, which itself is part of interface ICs in power management and signal-chain hierarchies. Unlike optocouplers, Si84xx parts use CMOS differential signaling and offer 10x faster propagation, 10x lower power, and superior CMTI.
Key features: the SI8422BB-D-IS integrates Skyworks' proprietary RF-coupled isolation technology with on-chip 2.5 kV RMS isolation, 20 kV/µs typical common-mode transient immunity (CMTI), and 2.70 V to 5.5 V wide supply operation on both sides. The device is fail-safe selectable (default low or default high) to control output state during input power loss, and operates across the -40 °C to +125 °C industrial temperature range. The 8-SOIC narrow-body footprint enables drop-in optocoupler replacement on existing PCB designs.
Architecturally, the Si8422 employs an RF carrier modulated by the input data on each side, demodulated across an integrated isolation barrier, then reconstructed at the destination. Both transmitter and receiver sides are independently powered (VDD and VISO rails), providing full galvanic isolation for SPI, I2C, GPIO, or general-purpose logic isolation in industrial bus applications. The CMOS architecture eliminates the LED aging and current-transfer-ratio drift inherent to optocouplers.
Typical applications include isolated SPI between MCU and motor-driver gate driver, isolated UART/RS-485 transceivers, industrial field-bus interfaces, isolated gate-drive bias for SiC/IGBT half-bridges, and automotive CAN-FD isolation. The Si8422BB-D-IS is also AEC-Q100 qualified per the manufacturer's data sheet, making it suitable for automotive powertrain and BMS use cases.
Design consideration: place 0.1 µF bypass capacitors close to both VDD and VISO pins, and ensure that input and output channels are referenced to their respective grounds (GND1 and GND2) - never tie these grounds together at the IC. Per Skyworks' data sheet, the Si8422BB-D-IS shares the Si8410/Si8420/Si8421 8-SOIC footprint, simplifying PCB reuse across channel-count variants.
This page synthesizes drop-in alternatives (Si8422 family variants and TI ISO7221x/ISO7721x pin-compatible parts), distributor pricing as of 2026-10-06, and practical design notes not found in the manufacturer's data sheet.
Drop-in alternatives for SI8422BB-D-IS — 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 SI8422BB-D-IS (same form factor and footprint) — differing in Common-Mode Transient Immunity (CMTI), Package, Technology, Number of Channels, Channel Configuration.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
SI8422AB-D-IS
✅ Drop-In📋 Reference alternative (not in catalog)
SI8422BB-D-ISR
✅ Drop-In📋 Reference alternative (not in catalog)
SI8420BB-D-IS
✅ Drop-In📋 Reference alternative (not in catalog)
SI8421BB-D-IS
✅ Drop-In📋 Reference alternative (not in catalog)
ISO7221M
✅ Drop-In📋 Reference alternative (not in catalog)
SI8422BB-D-IS Specifications
| Isolation Rating | 2500 V RMS |
| Channels | 2 (1 forward + 1 reverse) |
| Maximum Data Rate | 150 Mbps |
| Propagation Delay | < 10 ns (worst case) |
| Supply Voltage Range | 2.70 V to 5.5 V (each side) |
| Common-Mode Transient Immunity (CMTI) | 20 kV/µs |
| Default Output State (Fail-Safe) | High (BB suffix; Low = AB) |
| Operating Temperature | -40 °C to +125 °C (industrial) |
| Package | 8-SOIC narrow body (0.154", 3.90 mm width) |
| Mounting Type | Surface Mount |
| Technology | CMOS, RF-coupled isolation |
| AEC-Q100 Qualification | Yes (automotive grade) |
| Safety Certifications | UL, CSA, VDE certified |
| RoHS Status | RoHS-compliant (JEDEC 260 °C reflow) |
| MSL Level | MSL 2A |
SI8422BB-D-IS Pin Configuration
| Pin 1 | VDD — Side 1 power supply, 2.7 V to 5.5 V |
| Pin 2 | GND1 — Side 1 ground reference (isolated from GND2) |
| Pin 3 | IN1 — Logic input, channel 1 (side 1 to side 2) |
| Pin 4 | IN2 — Logic input, channel 2 (side 2 to side 1, reverse channel) |
| Pin 5 | GND2 — Side 2 ground reference (isolated from GND1) |
| Pin 6 | OUT2 — Logic output, channel 2 (from IN2) |
| Pin 7 | OUT1 — Logic output, channel 1 (from IN1) |
| Pin 8 | VISO — Side 2 isolated power supply, 2.7 V to 5.5 V |
Typical Applications
SI8422BB-D-IS is suitable for 7 applications: Isolated SPI Bus, Isolated UART / RS-485 Interface, Industrial Fieldbus & Motor Drive Isolation, IGBT / SiC Gate Driver Bias Supply Isolation, Battery Management System (BMS) Communication Isolation, Medical Device Patient-Isolation Interface, Isolated GPIO & Industrial Control Logic.
Isolated SPI Bus
The SI8422BB-D-IS is a strong fit for isolated SPI between a 3.3 V MCU and a 5 V motor-driver or sensor front-end. With 150 Mbps maximum data rate and <10 ns propagation delay, the device easily handles 20 MHz SCK clocks plus MOSI/MISO framing, while the 20 kV/µs CMTI rejects switching transients from the half-bridge. Placed between the MCU's SCK/MOSI/MISO lines and the isolated gate driver, the Si8422 eliminates ground loops and prevents high-side transients from reaching the controller. The 2.5 kV isolation meets IEC 60747-17 basic insulation for industrial SPI links.
Recommended
Isolated UART / RS-485 Interface
The SI8422BB-D-IS fits UART and RS-485/RS-422 transceiver isolation in industrial fieldbus nodes. With 1 forward + 1 reverse channel, the part provides TX and RX paths across the barrier in a single 8-SOIC, replacing two optocouplers and saving PCB area. The 150 Mbps capability far exceeds the 115.2 kbaud to 12 Mbps typical UART rates, leaving timing margin for protocol overhead. The 20 kV/µs CMTI rejects common-mode noise from motor inverters and AC drives sharing the same chassis ground reference.
Recommended
Industrial Fieldbus & Motor Drive Isolation
The SI8422BB-D-IS is well-suited to industrial CAN-FD, Modbus, and PROFIBUS isolation in factory automation and motor-control designs. Its 2.5 kV rating covers the reinforced insulation for 230 V AC line-side transients, while the 20 kV/µs CMTI withstands the dv/dt from adjacent IGBT modules in the same enclosure. Placed between a CAN-FD transceiver and the bus-bar side, the Si8422 provides safety isolation and ground-shift immunity for nodes subject to large earth-potential differences.
Recommended
IGBT / SiC Gate Driver Bias Supply Isolation
The SI8422BB-D-IS isolates logic-level PWM signals driving IGBT or SiC gate drivers in EV traction inverters and solar inverters. With <10 ns propagation delay and 20 kV/µs CMTI, the part accurately reproduces 50 ns PWM edges without distortion that could cause shoot-through. The 2.5 kV basic isolation suits low-voltage gate-drive bias applications; for reinforced 5 kV isolation choose the Si8412xx or ISO7721 wide-body variant. AEC-Q100 qualification makes the Si8422BB-D-IS suitable for automotive powertrain designs.
Recommended
Battery Management System (BMS) Communication Isolation
The SI8422BB-D-IS is used in BMS slave modules to isolate daisy-chain communication between high-voltage cell monitors and the low-voltage master MCU. The 2.5 kV rating is sufficient for the 400 V or 800 V traction battery isolation barrier, while the 150 Mbps capability supports daisy-chain protocols like daisy-chain SPI used by many cell-monitoring ICs. The AEC-Q100 grade is mandatory for automotive BMS designs subject to ISO 26262 functional-safety requirements.
Recommended
Medical Device Patient-Isolation Interface
The SI8422BB-D-IS supports IEC 60601-1 patient-isolation requirements in medical monitoring and diagnostic equipment. With 2.5 kV RMS isolation and 2-channel bidirectional signaling, the part can isolate ECG/EEG analog front-end digital outputs from the host processor. The 20 kV/µs CMTI and low leakage make it suitable for patient-connected circuits. Note: IEC 60601-1 reinforced isolation typically requires 5 kV (MOPP) — for MOPP-grade applications use the Si8422 5 kV wide-body variant or ISO7721.
Recommended
Isolated GPIO & Industrial Control Logic
The SI8422BB-D-IS serves as a general-purpose isolated GPIO in PLC digital input modules, isolated switch inputs, and industrial control logic where 24 V field-side signals must be level-translated to 3.3 V MCU logic. The 1 forward + 1 reverse channel configuration handles a single bidirectional logic signal in one IC, while 20 kV/µs CMTI tolerates the dv/dt from adjacent relay and contactor switching. The wide 2.7-5.5 V supply supports either 3.3 V or 5 V field-side rails.
Recommended
Recommended Products Summary
Engineering reference data for SI8422BB-D-IS — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | SI8422AB-D-IS | SI8422BB-D-ISR | SI8420BB-D-IS | SI8421BB-D-IS | ISO7221M |
|---|---|---|---|---|---|---|
| Brand | Skyworks Solutions | Skyworks Solutions | Skyworks Solutions | Skyworks Solutions | Skyworks Solutions | Texas Instruments |
| Package | 8-SOIC narrow body | 8-SOIC narrow body - same | 8-SOIC narrow body - same | 8-SOIC narrow body - same | 8-SOIC narrow body - same | 8-SOIC narrow body - same |
| Isolation Rating | 2500 V RMS | 2500 V RMS | 2500 V RMS | 2500 V RMS | 2500 V RMS | 2500 V RMS |
| Channels | 2 (1F + 1R) | 2 (1F + 1R) | 2 (1F + 1R) | 1 (unidirectional) | 2 (2F) | 2 (1F + 1R) |
| Maximum Data Rate | 150 Mbps | 150 Mbps | 150 Mbps | 150 Mbps | 150 Mbps | 25 Mbps |
| CMTI | 20 kV/µs | 20 kV/µs | 20 kV/µs | 20 kV/µs | 20 kV/µs | 25 kV/µs |
| Fail-Safe Default | High | Low | High | High | High | High |
| AEC-Q100 Qualified | Yes | Yes | Yes | Yes | Yes | No |
Key Differentiators
- Fail-safe HIGH for fault-tolerant downstream logic (vs SI8422AB-D-IS)
- 150 Mbps data rate vs 25 Mbps for legacy optocouplers and ISO7221M (vs ISO7221M)
- Bidirectional 1F+1R in single 8-SOIC vs two optocouplers (vs PC817 + EL817 optocoupler pair)
- 20 kV/µs CMTI for noisy motor-drive environments (vs Standard optocouplers (5-10 kV/µs typical))
Design Notes
Per the Skyworks Solutions data sheet, place 0.1 µF low-ESR ceramic bypass capacitors within 2 mm of each VDD (pin 1) and VISO (pin 8) pin, and add a 1 µF bulk capacitor on each side. Both rails operate independently from 2.70 V to 5.5 V; under-voltage lockout (UVLO) trips below 2.4 V typical. Decouple GND1 (pin 2) and GND2 (pin 5) separately - never short these grounds together at the IC, as this defeats the isolation.
Per the Skyworks Solutions data sheet, maintain a 4 mm minimum creepage/clearance under the IC body between side-1 and side-2 copper pours to preserve 2.5 kV isolation. Avoid routing any side-1 or side-2 signal traces or vias beneath the IC body. Place input/output traces on outer layers only, and use the inner layer as a continuous GND reference. For PCB designs migrating from optocouplers, the same layout rules apply - the Si84xx pinout matches the 8-pin optocoupler footprint.
Estimated: the Si8422BB-D-IS <10 ns propagation delay translates to a maximum SCK frequency of ~50 MHz in SPI applications (5 ns clock high + 5 ns clock low minimum). For 20 MHz SCK at 5 V supply, the part delivers clean edges with <2 ns jitter per the data sheet. If routing distances exceed 25 mm on either side of the barrier, add source-series termination (22-33 Ω) close to the Si8422 output pins to suppress transmission-line reflections.
Per the Skyworks Solutions data sheet, do not apply data transitions before VDD and VISO are above the UVLO trip point (typically 2.4 V) - the part may output undefined logic during power-up. Tie unused inputs (IN1 or IN2) to GND or VDD on their respective side to prevent oscillation. The fail-safe default state (HIGH for 'B' suffix, LOW for 'A') only applies during power loss, not during normal operation - the output follows the input.
Per the Skyworks Solutions data sheet, the 8-SOIC narrow-body package has θJA ≈ 105 °C/W. At maximum supply current (3 mA per side) and 5.5 V supply, total dissipation is 33 mW - junction temperature rise above ambient is ~3.5 °C, well within industrial -40 °C to +125 °C limits. No thermal management is required for normal operation. For high-density designs, standard SOIC land pads and 1 oz copper are adequate.
Compliance Information
RoHS-compliant with 260 °C JEDEC reflow per the Skyworks Solutions data sheet. AEC-Q100 qualified for automotive applications. UL, CSA, and VDE safety approved.
