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Analog Devices Inc./Maxim Integrated ADUM1255ASA+
- Part No.:
- ADUM1255ASA+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Digital Isolators
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
ADUM1255ASA+.pdf
- Description:
- TWO CHANNEL, BIDIRECTIONAL I2C D
- Quantity:
- Payment:
- Shipping:
Inventory:4,199
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Product details
Overview
ADUM1255ASA+ from Analog Devices is a dual-channel I²C digital isolator with unidirectional SCL and bidirectional SDA, designed for galvanically isolated I²C/SMBus interfaces in harsh environments. It supports 2.25V–5.5V independent supplies on both sides, operates up to 2 MHz, features side-1 regulated low-voltage output (VOL1 ≤ 0.69 V), and enables hot-swap connection on side 2 during bus idle or STOP condition - critical for battery management and PoE systems.
For engineers reviewing the ADUM1255ASA+ datasheet, ADUM1255ASA+ pinout, ADUM1255ASA+ application, or ADUM1255ASA+ equivalent, this page delivers verified electrical specs, isolation ratings, thermal limits, hot-swap timing behavior, and side-specific VOL/VIL thresholds required for robust I²C bus design across voltage domains and safety-critical industrial deployments.
Technical Context
The ADUM1255ASA+ implements proprietary iCoupler® technology to achieve reinforced galvanic isolation between two ground domains. Its architecture separates clock (SCL) and data (SDA) paths: SCL1→SCL2 is strictly unidirectional input-to-output, while SDA1↔SDA2 uses bidirectional translation with side-1 logic-low regulation (0.64 V) and side-2 conventional open-drain buffers (VOL2 ≤ 0.4 V).
Hot-swap operation is enabled by precharging side-2 bus pins via 140 kΩ Thevenin impedance, followed by idle/STOP detection (75 µs timeout) before enabling isolation. Side-1 UVLO threshold is 1.48–1.65 V with 30 mV hysteresis; side-2 hot-swap enable occurs 102 ms after VDD2 rise.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Isolation Rating (Narrow SOIC) | 445 VRMS working voltage (VIOWM); 3000 VRMS for 1 min (UL 1577); 630 VPEAK reinforced (VIORM) |
| Data Rate | Up to 2 MHz SCL frequency - supports standard/fast-mode I²C without protocol modification |
| Supply Range | 2.25 V to 5.5 V on both VDD1 and VDD2 - enables level shifting between 3.3 V and 5 V domains |
| Output Low Voltage | Side 1: ≤0.69 V at 5 mA sink; Side 2: ≤0.4 V at 50 mA sink - ensures compatibility with legacy I²C devices requiring low VOL |
| Common-Mode Transient Immunity | ≥100 kV/µs - maintains signal integrity in high-noise motor control or power supply environments |
| Operating Temperature | −40°C to +125°C ambient - qualified for under-hood automotive, industrial PLC, and battery pack monitoring |
| Hot-Swap Enable Delay | 102 ms after VDD2 power-up - prevents bus contention during live insertion of isolated peripherals |
Pinout & Package
ADUM1255ASA+ is housed in an 8-pin narrow-body SOIC package (Outline 21-0041) with 4 mm creepage and clearance, rated for pollution degree 2 and material group I per CSA.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - VDD1 | Side 1 power supply | 2.25–5.5 V input; requires local 1 nF + 0.1 µF ceramic decoupling to minimize noise coupling into isolation barrier |
| 2 - SDA1 | Side 1 bidirectional data I/O | Open-drain output with regulated 0.64 V logic-low; translates bidirectionally with SDA2 across isolation barrier |
| 3 - SCL1 | Side 1 unidirectional clock input | Input-only; drives SCL2 unidirectionally; no clock stretching support on side 2 |
| 4 - GND1 | Side 1 reference ground | Must be isolated from GND2; forms primary-side return path for VDD1 and SDA1/SCL1 signals |
| 5 - GND2 | Side 2 reference ground | Isolated secondary-side return; must not share plane or trace with GND1 to preserve creepage/clearance |
| 6 - SCL2 | Side 2 unidirectional clock output | Open-drain output; mirrors SCL1 with propagation delay ≤133.3 ns (VDD = 5.5 V) |
| 7 - SDA2 | Side 2 bidirectional data I/O | Open-drain output with 0.4 V VOL at 50 mA; supports hot-swap precharge and idle-bus detection |
| 8 - VDD2 | Side 2 power supply | 2.25–5.5 V input; bypassed identically to VDD1; powers side-2 logic and hot-swap circuitry |
Key Features
| Feature | Design Value |
|---|---|
| Side-1 regulated VOL | 0.64 V logic-low output with ≥50 mV margin below VIH1 threshold - prevents latch-up on connected I²C slaves |
| Side-2 hot-swap readiness | Precharges SDA2/SCL2 to 0.3 × VDD2 via 140 kΩ impedance and validates bus idle/STOP before connection - eliminates data corruption during live insertion |
| High-current sinking on side 2 | 50 mA sink capability at SDA2/SCL2 - allows lower pull-up resistor values (e.g., 1 kΩ) for faster rise times and 2 MHz operation |
| Reinforced isolation certification | Pending IEC 60747-17, UL 1577, and IEC 62368-1 - validated for 3000 VRMS (narrow SOIC) with 630 VPEAK continuous rating |
| Wide supply and temp range | 2.25–5.5 V operation and −40°C to +125°C ambient rating - supports deployment in battery packs, motor drives, and industrial sensors |
Applications
| Isolated I²C Interface | Battery Management System (BMS) |
|---|---|
Use Scenario: Isolating microcontroller I²C master from high-voltage cell monitoring ICs in multi-cell lithium-ion stacks. IC Role / Device Role / Timing Role: ADUM1255ASA+ provides galvanic separation between controller domain (3.3 V) and high-side analog front-end (5 V), with unidirectional SCL and bidirectional SDA preserving full I²C protocol transparency. Use Value: Enables safe, noise-immune communication across >1 kV potential differences while maintaining 2 MHz data throughput for real-time cell voltage reporting. |
Use Scenario: Hot-plugging slave BMS modules into a powered main board without disrupting ongoing I²C transactions. IC Role / Device Role / Timing Role: ADUM1255ASA+ monitors SDA2/SCL2 for idle or STOP condition before connecting side 1, preventing bus lockup during module insertion. Use Value: Eliminates manual power cycling and firmware resets during field maintenance - improves system uptime and serviceability. |
| Power over Ethernet (PoE) | Industrial Motor Control |
Use Scenario: Isolating PoE PSE controller I²C interface from PD-side telemetry (temperature, current, fault status) in Class 4+ systems. IC Role / Device Role / Timing Role: ADUM1255ASA+ bridges 3.3 V controller and 5 V PD-side sensor domain, supporting fast-mode I²C at 400 kHz with side-2 hot-swap for modular PD designs. Use Value: Maintains functional safety compliance (IEC 62368-1) while enabling dynamic reconfiguration of powered devices without network interruption. |
Use Scenario: Interfacing isolated gate driver feedback sensors (e.g., current shunt monitors) to a central motion controller via I²C in variable-frequency drives. IC Role / Device Role / Timing Role: ADUM1255ASA+ withstands >100 kV/µs transients from IGBT switching noise and provides 445 VRMS working isolation between motor power stage and control logic. Use Value: Prevents ground-loop-induced measurement errors and protects controller from high dv/dt noise, improving torque accuracy and system reliability. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar I²C isolator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ADUM1250ARZ | Same pinout, identical functionality, but in 8-lead wide-body SOIC (VIOWM = 848 VRMS, creepage = 8 mm) | Required where higher isolation voltage or extended creepage is mandated by end-equipment safety standards (e.g., IEC 61010-1) | Select ADUM1250ARZ when 5000 VRMS withstand rating and 8 mm creepage are needed; ADUM1255ASA+ suffices for 3000 VRMS and 4 mm spacing requirements. |
| SI8602ED-B-IS | Dual-channel I²C isolator with bidirectional SCL; lacks side-1 VOL regulation and hot-swap idle-bus detection logic | Supports clock stretching on side 2 but cannot prevent bus contention during hot-insertion without external control logic | Choose SI8602ED-B-IS only if bidirectional clock is essential and hot-swap robustness is handled externally; ADUM1255ASA+ integrates both functions. |
Compared with ADUM1255ASA+, ADUM1250ARZ offers higher isolation margins in a wider package, while SI8602ED-B-IS trades integrated hot-swap safety for bidirectional clock flexibility - making ADUM1255ASA+ optimal for cost-sensitive, space-constrained I²C isolation where side-2 hot-plug resilience is mandatory.
Availability
ADUM1255ASA+ is available at Aetrix Electronics and suitable for isolated I²C/SMBus interfaces, battery management systems, and Power over Ethernet (PoE) applications requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant sourcing.
Supply support for ADUM1255ASA+ 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
Analog Devices, Inc. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets since 1965.
The ADUM1255ASA+ belongs to the ADuM125x family of I²C isolators engineered specifically for robust, hot-swappable, low-VOL digital isolation in safety-critical industrial and energy systems operating across wide temperature and voltage ranges.
FAQ
What is the maximum SCL frequency supported by ADUM1255ASA+?
The ADUM1255ASA+ supports I²C clock frequencies up to 2 MHz under specified conditions (VDD1/VDD2 = 2.25–5.5 V, CL = 20 pF, TA = −40°C to +125°C). This enables fast-mode Plus (Fm+) operation while maintaining full protocol compatibility and isolation integrity across both sides of the barrier.
Does ADUM1255ASA+ support clock stretching on side 2?
No, ADUM1255ASA+ does not support clock stretching on side 2. Its SCL1→SCL2 path is strictly unidirectional, meaning side 2 can only receive clock signals - it cannot hold SCL low to request additional time from the side 1 master. This design simplifies timing and avoids arbitration conflicts in controller-slave topologies.
What is the purpose of the regulated 0.64 V logic-low voltage on side 1 of ADUM1255ASA+?
The regulated 0.64 V VOL on side 1 ensures a minimum 45 mV margin below the side-1 input high threshold (VIH1 ≥ 0.52 V), preventing bus latch-up when interfacing with legacy I²C devices that have tight VIH/VOL windows. This built-in margin eliminates the need for external level-shifting or pull-up tuning.
How does ADUM1255ASA+ implement hot-swap protection on side 2?
ADUM1255ASA+ precharges SDA2/SCL2 to 0.3 × VDD2 using a 140 kΩ internal impedance, then monitors for either bus idle (both lines high) or STOP condition before enabling the isolation path. This sequence - initiated 102 ms after VDD2 power-up and validated within 75 µs - prevents data corruption during live insertion of side-2 peripherals.
What isolation certifications are pending for ADUM1255ASA+?
ADUM1255ASA+ has pending certifications for UL 1577 (3000 VRMS, 1 min), IEC 60747-17 (reinforced, 630 VPEAK), IEC/EN/CSA 62368-1, IEC/EN/CSA 61010-1, and CAN/CSA-C22.2 No. 14-18. All certifications apply to the 8-lead narrow SOIC package (Outline 21-0041) with material group I and pollution degree 2.
ADUM1255ASA+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Technology:
- Magnetic Coupling
- Type:
- CAN, I2C
- Isolated Power:
- Yes
- Number of Channels:
- 2
- Inputs - Side 1/Side 2:
- 2/1
- Channel Type:
- Unidirectional
- Voltage - Isolation:
- 3000Vrms
- Common Mode Transient Immunity (Min):
- 100kV/µs
- Data Rate:
- 2MHz
- Propagation Delay tpLH / tpHL (Max):
- 95.8ns, 128.4ns
- Pulse Width Distortion (Max):
- 94.2ns
- Rise / Fall Time (Typ):
- -, 20.3ns
- Voltage - Supply:
- 2.25V ~ 5.5V
- Grade:
- -
- Qualification:
- -
- Operating Temperature:
- -40°C ~ 125°C
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
ADUM1255ASA+ FAQ
1.How can I place an order for ADUM1255ASA+ through Aetrix?
Please submit a Request for Quotation (RFQ) for ADUM1255ASA+ 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 ADUM1255ASA+ reliable?
The price and inventory of ADUM1255ASA+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ADUM1255ASA+ is usually 5 days.
3.What payment methods are accepted for ADUM1255ASA+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ADUM1255ASA+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ADUM1255ASA+?
ADUM1255ASA+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ADUM1255ASA+ 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 ADUM1255ASA+?
For technical support, including ADUM1255ASA+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ADUM1255ASA+ requirements.
6.How does Aetrix verify that ADUM1255ASA+ is sourced from the original manufacturer or authorized distributors?
All ADUM1255ASA+ 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 ADUM1255ASA+ meets industry standards.
7.What is the process for return or replacement of ADUM1255ASA+?
All ADUM1255ASA+ units undergo pre-shipment inspection (PSI). If there is an issue with ADUM1255ASA+, 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 ADUM1255ASA+ part is unused and in its original packaging.
Return procedure for ADUM1255ASA+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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