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I2C and SMBus Solutions Slide 15

As discussed earlier, some applications have mixed voltage levels because of the continuing decrease in processor voltages, whereas the peripheral external devices, such as LEDs, remain at higher voltages. The I²C multiplexer or switch can also be used in this case for multiple applications at different VCCs and operating frequencies. An I²C switch basically expands the I²C bus as it splits the SCL and SDA signals from the master into one or more SCL and SDA channels, where each channel can support unique functions and needs. An advantage of these switches is their ability to isolate a portion of the I²C bus through I²C software. This saves valuable pins on the processor, which can be used for additional functionality. TI’s I²C multiplexers and switches also resolve I²C address conflicts. An example of this conflict would be three different I²C slave devices having the same I²C address. Looking at this diagram on the picture, it can be seen how each of the devices might come from different manufacturers where inadvertently the same I²C address was used. Additionally, as shown in the top two sensors, a designer would like to use two identical I²C slave devices. This device allows the designer to implement all of the desired devices with identical I²C addresses by enabling or disabling the separate I²C system lines through software implementation.

PTM Published on: 2007-11-27