IC Isolator with Unidirectional SCL, Idle-bus Hotswap and Low V

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 8-pin narrow- and widebody SOIC packages. The devices are rated for operation at ambient temperatures of -40°C to +125°C.

Applications

* Isolated I2C/SMBus Interface

* Battery Management Systems

* Power Over Ethernet (PoE)

* Motor Control Systems

* 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