This has been accomplished by eliminating optocouplers and support circuitry previously required in isolated I²C interfaces. The ADuM1250W is the industry’s first I²C digital isolator to carry an AEC-Q100 qualified –40°C to 125°C automotive temperature rating and is based on the ADuM125x family of I²C isolators that have been in volume production for over three years in a wide range of industrial, instrumentation, networking and other applications.

The I²C bus is a cost-effective, two wire interface between controllers and peripheral devices such as data converters, memory products, switches, sensors and power supply ICs. The bus uses bidirectional lines to transmit and receive signals over the same wire, allowing two-wire signalling of clock and data. This reduces complexity and cost by eliminating extra wiring and components. In a variety of HEV and automotive applications, controllers or peripherals are isolated from the bus to avoid interference or harmful voltage levels.

Typically, isolation has been achieved with optocouplers, but doing so increases the cost and complexity of the I²C interface because unidirectional optocouplers must be accommodated by separating each of the two bidirectional I²C channels into two unidirectional channels. The resultant four unidirectional channels are then each isolated with an optocoupler and recombined into two bidirectional channels.

The additional circuitry associated with the bidirectional/unidirectional conversions and the isolation of the four unidirectional channels adds complexity and cost that offset the intended benefits of the I²C bus. With the ADuM1250W isolator, this complexity and cost is avoided as a single component directly provides bidirectional isolation to both of the I²C lines. This small, complete isolation device ensures the signal integrity of the bidirectional I²C bus while reducing component count, cost, board space, and complexity.

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