Analog Devices ADuM1254 and ADuM1255 I2C Isolators provide two open-drain channels, one unidirectional and one bidirectional, for applications that require data to be transmitted in both directions on the same line but have a unidirectional clock. The outputs on side one contain 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, preventing latch-up action. Side two features traditional buffers that do not regulate logic-low output voltage. Analog Devices ADuM1255 isolators offer independent 2.25V to 5.5V supplies on both sides, and the devices operate up to 2MHz. The ADuM1255 furnishes a disturbance-free bus connection for hot-plug connections on side two by pre-charging the bus pins, monitoring the bus state for an idle bus, or detecting an I2C stop condition before connecting sides one and two.
