Analog Devices Inc./Maxim Integrated ADUM1255AWA+

Overview

ADUM1255AWA+ from Analog Devices is a reinforced galvanic I²C isolator with unidirectional SCL and bidirectional SDA, designed for isolated communication between controller-side (Side 1) and peripheral-side (Side 2) domains. It supports 2.25V–5.5V dual supplies, operates up to 2 MHz, delivers side-specific low-V_OL (0.69 V on Side 1, 0.4 V on Side 2), and enables hot-swap connection only during bus idle or STOP states - critical for battery management systems and PoE interfaces.

For engineers reviewing the ADUM1255AWA+ datasheet, ADUM1255AWA+ pinout, ADUM1255AWA+ application, or ADUM1255AWA+ equivalent, key selection criteria include its wide-body SOIC-8 package (8 mm creepage/clearance), reinforced 5000 V_RMS isolation rating, side-specific current sinking (5 mA Side 1 / 50 mA Side 2), and guaranteed operation from –40°C to +125°C in industrial environments.

Technical Context

The ADUM1255AWA+ implements two independent open-drain isolation channels: SCL1→SCL2 is strictly unidirectional (input on Side 1, output on Side 2), while SDA1↔SDA2 is bidirectional with active precharge and idle-bus detection logic on Side 2. Its side-specific buffer architecture prevents latch-up by enforcing ΔV_O/IT ≥ 45 mV between Side 1's regulated 0.64 V_OL and input threshold.

Hot-swap functionality relies on internal precharge (0.3×V_DD2, 140 kΩ Thevenin), glitch filtering (220 ns), and strict timing windows: t_{HS_EN} = 102 ms enables detection, then t_IDLE = 75 µs confirms bus quiescence before enabling cross-side connectivity - ensuring no data corruption during live insertion.

Key Specifications

Pinout & Package

ADUM1255AWA+ is housed in an 8-pin wide-body SOIC package (Outline 21-100415) with 8 mm creepage and clearance, optimized for reinforced isolation in high-voltage applications. Pin 1 is VDD1; pins 1–4 form the Side 1 domain (VDD1, SDA1, SCL1, GND1); pins 5–8 form the Side 2 domain (GND2, SCL2, SDA2, VDD2).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar I²C isolator applications.

Compared with ADUM1255AWA+, ADUM1250ARZ offers identical functionality in a smaller footprint but reduced isolation margin, while SI8602ED-B-IS trades integrated bidirectional SDA and hot-swap logic for higher channel count flexibility - making ADUM1255AWA+ the sole choice for drop-in, standards-compliant I²C isolation with live-insertion support.

Availability

ADUM1255AWA+ is available at Aetrix Electronics and suitable for battery management systems, Power over Ethernet infrastructure, and motor control systems requiring stable component supply, long-term industrial lifecycle support, and certified reinforced isolation.

Supply support for ADUM1255AWA+ 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 precision instrumentation, industrial automation, and communications markets.

The ADUM1255AWA+ belongs to Analog Devices' iCoupler® digital isolation product line, engineered specifically for robust, low-latency, standards-compliant isolation of I²C, SMBus, and other bidirectional serial buses in harsh electrical environments.

FAQ

What is the isolation voltage rating of the ADUM1255AWA+?

The ADUM1255AWA+ is rated for 5000 V_RMS isolation for 60 seconds per UL 1577 and has a maximum working isolation voltage (V_IOWM) of 848 V_RMS. This wide-body SOIC package achieves 8 mm creepage and clearance, qualifying it for reinforced insulation in IEC 62368-1 and IEC 61010-1 applications up to 600 V mains.

Does the ADUM1255AWA+ support bidirectional communication on both SDA and SCL lines?

No - the ADUM1255AWA+ implements unidirectional clock transfer (SCL1 → SCL2 only) and bidirectional data transfer (SDA1 ↔ SDA2). This architecture prevents clock stretching conflicts and bus contention, making it ideal for topologies where all I²C controllers reside on one side of the isolation barrier.

How does hot-swap functionality work on the ADUM1255AWA+?

The ADUM1255AWA+ precharges SDA2/SCL2 to 0.3×V_DD2 via 140 kΩ internal resistors, filters glitches (220 ns), waits 102 ms for stabilization (t_{HS_EN}), then verifies bus idleness for 75 µs (t_IDLE) before enabling cross-side connectivity - eliminating data corruption during live insertion.

What are the supply voltage requirements for ADUM1255AWA+ operation?

The ADUM1255AWA+ requires independent 2.25 V to 5.5 V supplies on both Side 1 (VDD1) and Side 2 (VDD2). Each supply must be bypassed with a 1 nF capacitor in parallel with a 0.1 µF ceramic capacitor placed as close as possible to the respective VDD pin to ensure stable operation across the full –40°C to +125°C range.

Can ADUM1255AWA+ interface between 3.3 V and 5 V I²C domains?

Yes - the ADUM1255AWA+ supports independent VDD1 and VDD2 supplies, allowing direct interfacing between 3.3 V microcontrollers (Side 1) and 5 V peripherals (Side 2). Its side-specific VOL specifications (0.69 V max on Side 1, 0.4 V max on Side 2) ensure compatibility with both voltage domains' input thresholds.