THVD1424: Differential signaling issue

Nivrutti Damdhar

Part Number: THVD1424

Hello Team,
We are using the THVD1424 Transceiver IC for 485/422 Communication along with a ESP32 microcontroller. The set up is as follows
1) MCU TXD -> D pin of Transceiver
2) MCU RXD -> R pin of Transceiver
3) MCU GPIO -> DE/RE(combined) pin of Transceiver

additionally H/F pin tied to VCC and VCC = 3.3V, Vio = 3.3V.

When we observed waveforms through DSO we saw Identical signals(Y & Z lines) on DSO we have attached image for reference this was the case for Transmission only for reception we received correct data as well as as the signals were complementary too.

we then probed the TX pin of MCU it was behaving as intended we also checked DE/RE toggling it was also correct.

at the end we were unable to decern the issue! could you please guide us on this

Thank You for the Support in advance.

13 days ago

0 BOBBY 13 days ago

TI__Guru* 81401 points

Nivrutti,

Can you share the schematic for the device?

Can you also explain why the scopeshot has the yellow signal below GND? If you're probing the Y/Z pins, they should be based around the same common mode but it looks like the GND reference of the yellow one is off.

-Bobby

0 Nivrutti Damdhar 12 days ago

Prodigy 10 points

Hello Bobby,

Thanks for the reply.
Actually, we are currently evaluating this IC for our device, till now we have not designed any schematic we are currently testing it on IO expander board. as per your concern, we had separated them to check the waveforms, but at the time of measuring we had ensured that common mode GND reference is there.

If you have any sample schematic for this particular IC, it will help us to refer for designing.

0 Nivrutti Damdhar 12 days ago in reply to BOBBY

Prodigy 10 points

Hello Bobby,

The Issue got resolved, there was problem in our side circuit.

Interface

Interface forum

THVD1424: Differential signaling issue