The PCA9548A device has eight bidirectional translating switches that can be controlled through the I2C bus. The SCL/SDA upstream pair fans out to eight downstream pairs, or channels. Any individual SCx/SDx channel or combination of channels can be selected, determined by the contents of the programmable control register. These downstream channels can be used to resolve I2C slave address conflicts. For example, if eight identical digital temperature sensors are needed in the application, one sensor can be connected at each channel: 0-7.
The system master can reset the PCA9548A in the event of a time-out or other improper operation by asserting a low in the RESET input. Similarly, the power-on reset deselects all channels and initializes the I2C/SMBus state machine. Asserting RESET causes the same reset and initialization to occur without powering down the part. This allows recovery should once of the downstream I2C buses get stuck in a low state.
The pass gates of the switches are constructed so that the VCC pin can be used to limit the maximum high voltage, which is passed by the PCA9548A. This allows the use of different bus voltages on each pair, so that 1.8-V, 2.5-V or 3.3-V parts can communicate with 5-V parts, without any additional protection. External pull-up resistors pull the bus up to the desired voltage level for each channel. All I/O pins are 5-V tolerant.
| Top documentation | Type | Title | Format options | Date |
|---|---|---|---|---|
| * | Data sheet | PCA9548A Low Voltage 8-Channel I2C Switch with Reset datasheet (Rev. G) | PDF | HTML | Mar 11, 2021 |
| Application note | I2C Solutions for Hot Swap Applications (Rev. A) | Jan 31, 2023 | ||
| Application note | I2C Dynamic Addressing | Apr 25, 2019 | ||
| Application note | Choosing the Correct I2C Device for New Designs | PDF | HTML | Sep 7, 2016 | |
| Application note | Understanding the I2C Bus | PDF | HTML | Jun 30, 2015 | |
| Application note | Maximum Clock Frequency of I2C Bus Using Repeaters | May 15, 2015 | ||
| Application note | I2C Bus Pull-Up Resistor Calculation | PDF | HTML | Feb 13, 2015 |
For additional terms or required resources, click any title below to view the detail page where available.
The TCA9548AEVM is designed to evaluate and demonstrate the functionality of TI’s TCA954xA family of I2C switches. The TCA9548AEVM can be used as a standalone evaluation module to interface with an existing system or paired with the MSP430 Lauchpad which serves as the I2C master and power supply (...)
| Package | Pins | CAD symbols, footprints & 3D models |
|---|---|---|
| SOIC (DW) | 24 | Ultra Librarian |
| SSOP (DB) | 24 | Ultra Librarian |
| TVSOP (DGV) | 24 | Ultra Librarian |
| TSSOP (PW) | 24 | Ultra Librarian |
| VQFN (RGE) | 24 | Ultra Librarian |
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