The PCA9545A is a quad bidirectional translating switch controlled via the I2C bus. The SCL/SDA upstream pair fans out to four downstream pairs, or channels. Any individual SCn/SDn channel or combination of channels can be selected, determined by the contents of the programmable control register. Four interrupt inputs ( INT3– INT0), one for each of the downstream pairs, are provided. One interrupt ( INT) output acts as an AND of the four interrupt inputs.
An active-low reset ( RESET) input allows the PCA9545A to recover from a situation in which one of the downstream I2C buses is stuck in a low state. Pulling RESET low resets the I2C state machine and causes all the channels to be deselected, as does the internal power-on reset function.
The pass gates of the switches are constructed such that the VCC terminal can be used to limit the maximum high voltage, which will be passed by the PCA9545A. 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 terminals are 5.5 V tolerant.
| Type | Title | Date | ||
|---|---|---|---|---|
| * | Data sheet | PCA9545A Low Voltage 4-channel I2C and SMbus Switch With Interrupt Logic and Reset Functions datasheet (Rev. E) | PDF | HTML | 11 Mar 2021 |
| Application note | I2C Solutions for Hot Swap Applications (Rev. A) | 31 Jan 2023 | ||
| Application note | I2C Dynamic Addressing | 25 Apr 2019 | ||
| Selection guide | Logic Guide (Rev. AB) | 12 Jun 2017 | ||
| Application note | Choosing the Correct I2C Device for New Designs | PDF | HTML | 07 Sep 2016 | |
| Application note | Understanding and Interpreting Standard-Logic Data Sheets (Rev. C) | 02 Dec 2015 | ||
| Application note | Understanding the I2C Bus | PDF | HTML | 30 Jun 2015 | |
| Application note | Maximum Clock Frequency of I2C Bus Using Repeaters | 15 May 2015 | ||
| Application note | I2C Bus Pull-Up Resistor Calculation | PDF | HTML | 13 Feb 2015 | |
| Application note | Programming Fun Lights With TI's TCA6507 | 30 Nov 2007 | ||
| Application note | Semiconductor Packing Material Electrostatic Discharge (ESD) Protection | 08 Jul 2004 |
For additional terms or required resources, click any title below to view the detail page where available.
| Package | Pins | CAD symbols, footprints & 3D models |
|---|---|---|
| SOIC (DW) | 20 | Ultra Librarian |
| TSSOP (PW) | 20 | Ultra Librarian |
| VQFN (RGY) | 20 | Ultra Librarian |
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