PCA9546A: PCA9546A not passing through the I2C commands to the devices after the switch

Jason Song

Part Number: PCA9546A

Hi TIer,

I changed the schematic based on the inputs I got from the E2E and here is the schematic.

At CH0, I have four I2C MUX connected, and here is one of them.

I am using a PMBUS to run the communication. I can write to the PCA9546A and read back using address 0x70. I am writing "00000001" to turn on CH0. But I was not able to reach out to address 0X4F as shown in the schematic, and when I sent a command there, I got a False return code. In another design, without the I2C switch, we are able to communicate with the 0X4F without a problem.

Do you see any problem with the schematic and any suggestions?

Regards,

Jason

over 3 years ago

+1 Chris Ayoub over 3 years ago

TI__Genius 15345 points

Hi Jason,

Your schematic looks fine.

Do you have a scope shot of the SC0 and SD0 bus when you try to communicate to the MUX? If so can you send me the scope shot.

Also can you provide a scope shot of the entire write that enables the SC0 and SD0 channel?

Best,

Chris

0 Jason Song over 3 years ago in reply to Chris Ayoub

Prodigy 100 points

Hi Chris,

Upon checking the waveforms myself, I was able to fix the problem.

Thank you,

Jason

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PCA9546A: PCA9546A not passing through the I2C commands to the devices after the switch