General Description

The ADuM1255 offers two open-drain channels, one

unidirectional and one bidirectional for applications,

such as I2C, that require data to be transmitted in both

directions on the same line, but have a unidirectional

clock. To prevent latch-up action, side 1 outputs

comprise special buffers that regulate the logic-low

voltage at 0.64V, and the input logic-low threshold is at

least 50mV lower than the output logic-low voltage. Side

2 features conventional buffers that do not regulate

logic-low output voltage.

The ADuM1255 features independent 2.25V to 5.5V

supplies on both side 1 and side 2 of the isolator. The

device operates up to 2MHz.

The ADuM1255 provides a disturbance-free bus

connection for hot-plug connections on side 2 by first

precharging the bus pins and then monitoring the bus

state for either an idle bus or detection of an I2C stop

condition before connecting side 1 and side 2.

The ADuM1255 is available in an 8-pin narrow-body

SOIC package. The devices are rated for operation at

ambient temperatures of -40°C to +125°C.

Key Applications

? Isolated I2C/SMBus Interface

? Battery Management Systems

? Power Over Ethernet (PoE)

? Motor Control Systems

Benefits and Features

? Low VOL(MAX) for Greater I2C Device Compatibility

? Side 1: 0.69V

? Side 2: 0.4V

? Independent VDD1/VDD2 Supplies Support 3.3V and

5V Logic Voltage Levels and Allow Level Shifting

? 2.25V to 5.5V for Both Sides

? Hot-Swappable Side 2 I/O Prevents Data Corruption

? Initial Side 2 Connection Occurs at Bus Idle or

Stop States

? Bidirectional I2C Data Transfer up to 2MHz SCL

? Strong Current Sinking Enables Lower RPULL-UP

Values for Faster Bus Speeds

? Side 1: 5mA

? Side 2: 50mA

? Robust Galvanic Isolation of Digital Signals

? Continuously Withstands (VIOWM)

- 8-Narrow SOIC: 445VRMS

? Withstands ±10kV Surge per IEC 61000-4-5

? Package Creepage and Clearance

- 8-Narrow SOIC: 4mm

? Safety and Regulatory Approvals (Pending)

? IEC60747-17 (Pending)

- Reinforced VIORM Narrow SOIC: 630VPEAK

? UL 1577 (Pending)

- 8-Narrow SOIC: 3000VRMS for 1min

? IEC/EN/CSA 62368-1 (Pending)

? IEC/EN/CSA 61010-1 (Pending

? CAN/CSA-C22.2 No. 14-18 (Pending)