2.5-kVrms, isolated unidirectional clock, bidirectional I2C isolator

The ISO1540 and ISO1541 devices are low-power, bidirectional isolators that are compatible withI2C interfaces. These devices have logic input and output buffers thatare separated by Texas Instruments Capacitive Isolation technology using a silicon dioxide(SiO2) barrier. When used with isolated power supplies, these devices blockhigh voltages, isolate grounds, and prevent noise currents from entering the local ground andinterfering with or damaging sensitive circuitry.

This isolation technology provides for function, performance, size, and power consumptionadvantages when compared to optocouplers. The ISO1540 andISO1541 devices enable a completeisolated I2C interface to be implemented within a small formfactor.

The ISO1540 has twoisolated bidirectional channels for clock and data lines while the ISO1541 has a bidirectional dataand a unidirectional clock channel. The ISO1541 is useful in applications that have a single master while theISO1540 is suitable formulti-master applications. For applications where clock stretching by the slave is possible, theISO1540 device should beused.

Isolated bidirectional communication is accomplished within these devices by offsettingthe low-level output voltage on side 1 to a value greater than the high-level input voltage on side1, thus preventing an internal logic latch that otherwise would occur with standard digitalisolators.