PCA9546A: Comparison and questions

The difference between PCA and TCA devices is that the latter support lower voltages, and sometimes have bug fixes or improved performance. The difference between the '46 and the '44 is that the latter has voltage translation for interrupt signals.

You should use the TCA9546A, unless you need to handle interrupt signals.

The PCA9546A and PCA9546A appear to be identical.

As shown in figure 9-2, the pass transistors allow voltages that are somewhat lower than V_CC.

Hi Daniel,

Daniel De Sousa said:

What is the difference between PCA9546 and TCA9544A? Which is recommended for an application which involves an MCU talking to 4 sensors over I2C with the same address?

Clemens listed out most of the differences already, but I can re-iterate some of the improvements here.

TCA devices that are of the same part number of the PCA version are p2p compatible. For example, TCA9546A is p2p to PCA9546A.

TCA devices are characterized up to 400kHz, while PCA devices are usually characterized only up to 100kHz. 

TCA device may have bug fixes or improved electrical characteristics compared to the previous PCA generation of devices. You can think of the hierarchy as follows: PCA -> TCA -> TCAL, with our TCAL family having the most improved electrical characteristics, 1MHz data rate support, and improved process technology, lower voltage range as well. 

Daniel De Sousa said:

How is the TI part different from the NXP variant?

It is not suppose to be much different. There might be some slight differences in specs such as Ron or input cap, but overall they should be p2p compatible replacements for eachother. 

Daniel De Sousa said:

The datasheet says "Allows Voltage-Level Translation Between 1.8-V, 2.5-V, 3.3-V, and 5-V Buses " but VCC does not go low enough to support 1.8V. Can this be used with a 1.8V bus or not?

I am assuming this is for the PCA9546A. While VCC(min) = 2.3V, this device can still support level translation down to 1.8V because the input and output sides pull-up voltage VDPUx can be pulled-up to a voltage lower than VCC. 

It is recommended that the customer move to TCA9546A however, since this is a newer device with more reputable qualities. 

Regards,

Tyler

Hi Daniel,

Main difference between the two devices is that the 9544A has level translating interrupt inputs that can be used by the master / mcu. 

Regards,

Tyler