ISOW7741DFMEVM: ISOW7741DFMEVM not sending data as digital UART ISOLATOR

Sumit Mourya

Expert 1790 points

Part Number: ISOW7741DFMEVM
Other Parts Discussed in Thread: ISOW7741, ISOW7721

Hello Team,

I'm evaluating ISOW7741DFMEVM for isolating UART Signals.

My Setup is as follows

CP2102 (USB/UART Converter) TX is connected to INA of the EVM

MCU RX is connected to OUTA of the EVM

MCU TX is connected to INB of the EVM

CP2102 (USB/UART Converter) RX is connected to OUTB of the EVM

The Hardware Setup is

CP2102 - ISOW7741- MCU

The input to ISOW7741 is 3.3V and VISOUT of the integrated DC-DC Converter is also 3.3V which is going to the MCU and other peripherals like ADC etc.

The issue is that with the above Setup , My UART is not working as no data is being transferred to the PC.

If I remove the ISOW7741 from between both the IC's the UART Works fine.

kindly suggest

over 1 year ago

0 Koteshwar Rao over 1 year ago

TI__Guru 55575 points

Hi Sumit,

Thank you for reaching out.

If you are planning to use ISOW7741DFMEVM for UART communication then you would be required to use two channels of ISOW7741 with one in forward direction and the other in reverse direction to be able to transmit and receive data. ISOW7741 has 3 forward channels (A, B & C) and one reverse channel (D), hence, you would need to use the reverse channel (IND/OUTD) and one channel from the remaining forward channels.

Please try the above suggestion and test. Let us know if you find any further issues. Thanks.

Regards,
Koteshwar Rao

0 Sumit Mourya over 1 year ago in reply to Koteshwar Rao

Expert 1790 points

Hello Koteshwar,

Thanks for replying. I tried your suggested channels and UART started working.

I was able to send and receive data properly.

Secondly, I will be using ISOW7721 in my final design since I need only 2 channels for UART. Does ISOW7721 also has forward and reverse channels?

0 Koteshwar Rao over 1 year ago in reply to Sumit Mourya

TI__Guru 55575 points

Hi Sumit,

Thanks for trying out the suggestion and glad to know that UART is working fine.
Yes, ISOW7721 has one forward channel and one reverse channel. Please do go through the below FAQ to understand what the part number for digital isolators represents and how to know how many channels are available in each part number.

https://e2e.ti.com/support/isolation-group/isolation/f/isolation-forum/719547/faq-how-do-i-read-ti-s-digital-isolator-part-numbers

Let me know if you have any further questions, thanks.

Regards,
Koteshwar Rao

Isolation

Isolation forum

ISOW7741DFMEVM: ISOW7741DFMEVM not sending data as digital UART ISOLATOR