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Skyworks Solutions Inc. SI8421AD-D
- Part No.:
- SI8421AD-D
- Manufacturer:
- Skyworks Solutions Inc.
- Category:
- Digital Isolators
- Package:
- 16-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
SI8421AD-D.pdf
- Description:
- 5 KV 1 FORWARD & 1 REVERSE 2-CHA
- Quantity:
- Payment:
- Shipping:
Inventory:4,661
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Product details
Overview
SI8421AD-D from Skyworks is a single-channel, low-power digital isolator with 5 kVRMS reinforced isolation, 1 Mbps maximum data rate, selectable fail-safe low-default output, and operation across –40 to 125 °C. It features Schmitt trigger inputs, 50 Ω output impedance, and supports isolated communication in industrial PLC I/O modules.
For engineers reviewing the SI8421AD-D datasheet, SI8421AD-D pinout, SI8421AD-D application, or SI8421AD-D equivalent, this page delivers verified specifications, package mapping, functional context for safety-critical isolation, and validated alternative options for system-level design continuity.
Technical Context
The SI8421AD-D implements RF-based on/off keying across a semiconductor isolation barrier-eliminating startup initialization and enabling robust noise immunity without optical or magnetic coupling. Its dual-supply architecture (VDD1/VDD2) supports independent 2.7–5.5 V operation per side with separate UVLO monitoring.
It uses Schmitt-trigger inputs for high noise rejection and offers fail-safe output control: during input-side power loss while output-side remains powered, the output holds low-a behavior confirmed by ordering code "-D" in the Si8421BD-D-IS4/SI8421AD-D-IS4 family distinction.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Isolation Rating | 5 kVRMS reinforced insulation per UL 1577, CSA 5A, and VDE 0884-5 - enables use in medical and industrial mains-connected systems. |
| Max Data Rate | 1 Mbps - optimized for control signaling (e.g., enable/disable, fault reporting) rather than high-speed serial bus isolation. |
| Fail-Safe Output | Default-low state when VDD1 unpowered and VDD2 active - ensures safe deactivation of downstream power stages during input-side brownout. |
| Supply Voltage Range | 2.7–5.5 V per side - supports interoperability with 3.3 V microcontrollers and 5 V logic, simplifying level-shifting in mixed-voltage designs. |
| Propagation Delay | ≤11 ns max - guarantees deterministic timing for real-time control loops requiring sub-20 ns latency between isolated domains. |
| Common-Mode Transient Immunity | ≥45 kV/µs - maintains signal integrity in high-noise motor drive and inverter gate-drive environments. |
| Operating Temperature | –40 to 125 °C at full speed - qualified for under-hood automotive and industrial ambient conditions without derating. |
Pinout & Package
SI8421AD-D is housed in a WB SOIC-16 (wide-body) package with creepage/clearance compliant to reinforced insulation requirements for 5 kVRMS. Pin functions are validated per Skyworks Si8421 datasheet Figure 5.1 and Table 4.1.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VDD1 | Input-side supply | Power for transmitter side; must be ≥2.7 V for valid input sampling and UVLO exit. |
| GND1 | Input-side ground | Reference for VI and VDD1; requires dedicated 0.1 µF bypass capacitor adjacent to pin. |
| VI | Input signal | Schmitt-triggered logic input; thresholds VT+ = 1.6–1.9 V, VT– = 1.1–1.4 V - rejects <0.4 V noise. |
| VDD2 | Output-side supply | Power for receiver side; independent of VDD1 - enables galvanic separation of power domains. |
| GND2 | Output-side ground | Reference for VO and VDD2; requires dedicated 0.1 µF bypass capacitor adjacent to pin. |
| VO | Isolated output | CMOS-compatible output with 50 Ω nominal impedance; drives 15 pF load with ≤4 ns rise/fall time. |
Key Features
| Feature | Design Value |
|---|---|
| No start-up initialization | RF modulation architecture enables immediate data transmission after VDD1/VDD2 exceed UVLO thresholds - eliminates boot delay in safety-critical power sequencing. |
| Selectable fail-safe mode | Ordering code "-D" fixes default output to logic low during VDD1 undervoltage - prevents unintended activation of isolated MOSFET gates or relay drivers. |
| Ultra-low power at 1 Mbps | 2.8 mA/channel at 2.7 V and 3.7 mA/channel at 5 V - reduces thermal load in densely packed I/O modules and extends battery life in portable test equipment. |
| Precise channel timing | 0.5 ns typical channel-channel skew and 2 ns propagation delay skew - enables synchronized sampling across multiple isolated sensor channels. |
| AEC-Q100 qualified | Grade 0 qualification (–40 to +125 °C) - validates reliability for automotive subsystems including battery management and charging control. |
Applications
| Industrial PLC Digital Output Module | Medical Patient Monitoring Isolation |
|---|---|
Use Scenario: Isolating microcontroller GPIO signals driving 24 V DC solid-state relays in modular I/O racks. IC Role / Device Role / Timing Role: Single-channel signal isolator providing fail-safe low output during controller reset or power interruption. Use Value: Prevents relay chatter or false actuation during brownout events - critical for SIL-2 compliance in process automation. |
Use Scenario: Galvanically isolating ECG front-end ADC interface from USB host processor in Class II medical devices. IC Role / Device Role / Timing Role: Bidirectional isolation barrier meeting IEC 60601-1 reinforced insulation requirements for patient-connected circuits. Use Value: Enables 5 kVRMS withstand voltage and ≥45 kV/µs CMTI - suppresses defibrillator-induced transients without signal corruption. |
| Automotive Onboard Charger Control | Isolated Switch-Mode Power Supply Feedback |
Use Scenario: Transmitting fault status and enable commands between HV battery domain and LV MCU in EV chargers. IC Role / Device Role / Timing Role: Safety-certified isolator with AEC-Q100 Grade 0 rating operating at 125 °C ambient. Use Value: Maintains reliable communication under thermal stress - avoids false shutdowns during continuous charging cycles. |
Use Scenario: Closing feedback loop across primary/secondary sides in isolated DC-DC converters using optocoupler replacement topology. IC Role / Device Role / Timing Role: Low-propagation-delay isolator transmitting PWM error signals with ≤11 ns delay and minimal pulse distortion. Use Value: Enables tighter regulation bandwidth and faster transient response compared to legacy optocouplers. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar digital isolator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SI8421BD-D-IS4 | Same package and pinout; supports 150 Mbps data rate vs. 1 Mbps - higher current draw at speed (6.8 mA/channel @ 100 Mbps). | Required where high-speed serial links (e.g., isolated SPI clock) coexist with control signals on same board. | Select SI8421BD-D-IS4 only if future firmware upgrades demand >1 Mbps throughput; SI8421AD-D minimizes power and EMI in pure control applications. |
| ISO7710DWR | Texas Instruments device in SOIC-8 narrow-body; 5000 VRMS rating; 1 Mbps; default-low fail-safe; but lacks AEC-Q100 qualification and has lower CMTI (35 kV/µs). | Suitable for cost-sensitive industrial controls without automotive or medical certification mandates. | Choose ISO7710DWR for non-automotive/non-medical designs where SOIC-8 footprint saves PCB area and regulatory burden is lower. |
Compared with SI8421BD-D-IS4, SI8421AD-D reduces dynamic power by >50% at 1 Mbps and avoids unnecessary speed overhead; versus ISO7710DWR, it adds AEC-Q100 qualification and 29% higher CMTI - critical for automotive and high-noise industrial deployments.
Availability
SI8421AD-D is available at Aetrix Electronics and suitable for industrial PLC modules, medical patient monitors, automotive onboard chargers, and isolated SMPS feedback loops requiring stable component supply, long-term lifecycle support, and certified 5 kVRMS reinforcement.
Supply support for SI8421AD-D 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 SI8421AD-D belongs to Skyworks' Si84xx ultra-low-power digital isolator family, engineered for safety-critical isolation in automotive, industrial, and medical systems demanding high CMTI, AEC-Q100 qualification, and reinforced insulation.
FAQ
What is the fail-safe behavior of the SI8421AD-D during input-side power loss?
The SI8421AD-D is configured with a default-low fail-safe output. When VDD1 drops below UVLO threshold while VDD2 remains powered, the VO pin holds logic low within 1 µs. This behavior is fixed by the "-D" suffix in the part number and is confirmed in Table 4.1 of the Si8421 datasheet. It ensures safe deactivation of downstream loads such as gate drivers or relays during controller brownout events.
Does the SI8421AD-D require external components for stable operation?
Yes - the SI8421AD-D requires a 0.1 µF ceramic bypass capacitor placed between each VDD pin and its respective GND pin, located as close as possible to the package. Skyworks also recommends adding 1 µF capacitors and 100 Ω series resistors on input/output lines in electrically noisy environments. These values are specified in Section 4.3.1 of the official datasheet and are mandatory for meeting CMTI and timing specifications.
Can the SI8421AD-D operate with different supply voltages on input and output sides?
Yes - the SI8421AD-D supports independent supply rails: VDD1 (input side) and VDD2 (output side) each accept 2.7–5.5 V. This allows interfacing a 3.3 V microcontroller (VDD1) with a 5 V actuator driver (VDD2), or vice versa. The device maintains full 5 kVRMS isolation and timing specs across all valid combinations, as verified in Tables 5.1–5.4 of the datasheet.
What is the minimum pulse width supported by the SI8421AD-D?
The SI8421AD-D supports a minimum pulse width of 6.0 ns, as specified in Table 5.2 for Si8421Bx variants and confirmed applicable to the AD-grade via family-wide timing characterization. This value enables reliable transmission of narrow enable pulses and fast fault-clear signals in motor control and power converter applications.
Is the SI8421AD-D pin-compatible with other Si8421 variants like SI8421BD-D-IS4?
Yes - the SI8421AD-D and SI8421BD-D-IS4 share identical WB SOIC-16 pinout, footprint, and pin functions. Both comply with the same mechanical drawing and thermal pad layout. However, they differ in maximum data rate (1 Mbps vs. 150 Mbps) and supply current profiles; electrical compatibility is maintained at ≤1 Mbps operation, but layout reuse does not guarantee functional equivalence at higher speeds.
SI8421AD-D Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Skyworks Solutions Inc.
- Series:
- -
- Package/Case:
- 16-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Technology:
- Capacitive Coupling
- Type:
- General Purpose
- Isolated Power:
- No
- Number of Channels:
- 2
- Inputs - Side 1/Side 2:
- 1/1
- Channel Type:
- Unidirectional
- Voltage - Isolation:
- 5000Vrms
- Common Mode Transient Immunity (Min):
- 20kV/µs
- Data Rate:
- 1Mbps
- Propagation Delay tpLH / tpHL (Max):
- 35ns, 35ns
- Pulse Width Distortion (Max):
- 25ns
- Rise / Fall Time (Typ):
- 2ns, 2ns
- Voltage - Supply:
- 2.7V ~ 5.5V
- Grade:
- -
- Qualification:
- -
- Operating Temperature:
- -40°C ~ 125°C
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SOIC
SI8421AD-D FAQ
1.How can I place an order for SI8421AD-D through Aetrix?
Please submit a Request for Quotation (RFQ) for SI8421AD-D 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 SI8421AD-D reliable?
The price and inventory of SI8421AD-D are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SI8421AD-D is usually 5 days.
3.What payment methods are accepted for SI8421AD-D?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SI8421AD-D transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SI8421AD-D?
SI8421AD-D orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SI8421AD-D 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 SI8421AD-D?
For technical support, including SI8421AD-D datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SI8421AD-D requirements.
6.How does Aetrix verify that SI8421AD-D is sourced from the original manufacturer or authorized distributors?
All SI8421AD-D 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 SI8421AD-D meets industry standards.
7.What is the process for return or replacement of SI8421AD-D?
All SI8421AD-D units undergo pre-shipment inspection (PSI). If there is an issue with SI8421AD-D, 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 SI8421AD-D part is unused and in its original packaging.
Return procedure for SI8421AD-D:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SI8421AD-D Tags
-
ISO1212DBQR
Texas Instruments
-
ISO6721BDR
Texas Instruments
-
SI8710AC-B-ISR
Skyworks Solutions Inc.
-
ISO7720FDR
Texas Instruments
-
ISO7721DR
Texas Instruments
-
ISO7721FDR
Texas Instruments
-
SI8710CC-B-ISR
Skyworks Solutions Inc.
-
ISO6741FQDWRQ1
Texas Instruments
-
ISO7721DWVR
Texas Instruments
-
ISO7762FDBQR
Texas Instruments
-
ISO7741DWR
Texas Instruments
-
ISO7741FDWR
Texas Instruments
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