Part Number: ISO6421
Hello TI associates and thanks in advance for your help.
We are thinking of using ISO6421 in our design to isolate 4 different UART ports. Our current design is setup so that all 4 ports are pulled up to the same rail, 3.3V, of course with 10K pull-up resistors. We found out that the current configuration is causing a lot of noise on the 3.3V rail when "all" 4 ports are toggling. Meaning, when all 4 ports are receiving data, they cause noise on the 3.3V rail. And so we are thinking to implement ISO6421 device. However, we see that VCCI and VCCO are separated. And so, our question to your team is, are the individual Tx and Rx pins also separated from the internal pull-up rail? Meaning is Tx1 and Tx2 pulled up to separate rails? Also, if Tx1 is toggling, will it be sensed or affected if Tx2 starts toggling as well? We totally understand that ISO6421 is only 2 channel device, and so for our application will use the 4 channel counterpart of this device. However, it’s super important that we confirm the channels internal pull-ups. If the Tx and Rx channels are internally pulled up directly to the same rail, then I think we are accomplishing nothing at this point.
We would love to hear from your team and looking forward to it. Our entire application has been paused due to this issue. So your prompt response is greatly appreciated.
Thank you.
Regards.
