TCA9406 and TCA9555

Hello Nagai-San,

Sorry for the delay.  We are getting caught up after the holiday.  Can you expand on what you mean by "communicated"?  Are you asking if the TCA9555 (IO expander) can be connected with the TCA9406 (level shifter/translator)?  I am assuming that you are using a micro/processor with low voltage and want to interface with IO at higher voltage.  You can do it this way, but have you considered using the TCA6416A?  It has two voltage rails, one for I2C voltage level and one for IO level.

Let me know if this was what you intended.  Please try and put as much detail into your questions as possible so we can figure out what you are asking.

-Francis Houde

Hi Houde-san,

Thank you for reply.
TCA9406 Low-level input voltage is 0.15V(max), TCA9555 Low-level output voltage is 0.4V(at Isink=3mA).
I think, if many I2C-devices connected to communication line, the parasitic capacitance increases, these devices can't communicate.
My opinion is uncorrect?

Regards,
Nagai

Hello Nagai-san,
I think it might be easier to understand your concerns if you told me about your application. What is the I2C master, how many I2C peripherals (slaves) are on the I2C bus? Is this a large board or is there are harness between master and peripheral? What speed I2C do you wish to use? What voltage do you expect to use on both the I2C and I/O? What are the I/O interfacing with? What are the I/O output voltage requirements?

If you have schematic then I can review that and make suggestions. If it is sensitive information than we can communicate via email.
Sincerely,
-Francis Houde

Hi Houde-san,

I tried communicate to TCA9406 and multiple TCA9555. However, they combination was failed.
Communication between them could not be communicated properly.
Ack was can not to be properly voltage.
I changed TCA9406 to other device, they become to can commnication normality.
I suppose, TCA9406 and multiple TCA9555 combination is not appropriate, factor is TCA9406's electrical characteristics.

Regards,
Nagai

Hello Nagai-san,

Do you have waveforms of the transactions?  This should give us enough information to understand why it isn't working.

-Francis Houde

Hi Houde-san,

Thank you for cooperation.
I attached the file on this thread.
I look forward your comments.

Regards,
Nagai

1588.Issue_TCA9555.pdf

Hello Yoshitaka-san,

What are you using for pull-up resistor values for both sides of the bus? How many devices are on the bus?  Do you have oscilloscope shots of the SDA and SCL during this condition?

-Francis Houde

Hi Houde-san,

Pull-up resistor is 47-kohm.
Total 5-devices is connected on the bus.
Please see attached file.
 - Blue : SCL
 - Green : SDA
I look forward your update comment.

Regards,
Nagai

Regards,

Nagai

Nagai-san,

Is that 47k on both sides of TCA9406?  Are you sure you don't mean 4.7k Ohms?  What is the data rate you are trying to achieve?  400kHz?  If you have a 4 channel scope please take waveforms on both sides of TCA9406. 

-Francis Houde