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Electronic Design

I<sup>2</sup> C Switches Connect Multiple Devices On A Single Bus

The PCA954x I2C switches join numerous parts with the same I2C address on a single bus. They enable voltage-level shifting between devices operating at 5, 3.3, 2.5, or 1.8 V at serial clock frequencies up to 400 kHz. The switches provide multiplexing and interrupt control, eliminating the need for glue logic and general-purpose I/Os. Two-, four-, and eight-channel configurations are available in both SO and TSSOP packages. The switches have a hardware reset pin that returns the device to the default state of no channels selected. This feature circumvents the usual step of cycling power to restore the bus from a lockup situation. In 10,000-unit quantities, the PCA9543, PCA9545, PCA9546, and PCA9548 are priced at $0.77, $0.92, $0.75, and $1.19 each, respectively.

Royal Philips Electronics

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