SN65HVD3085E: Driver function fail

Hi,

Nothing seems wrong from the schematic perspective.

Can you describe the failure that you are seeing from the driver? If you oscilloscope shots of the failure that you are seeing that would be super helpful. 

During testing how many nodes is the transceiver connected to?

What were the test conditions that these fail conditions appear under? 

Please let me know so I can look into the issue a little deeper - from what you have provided so far I don't know if its an application issue since its an old design but I want to do a couple checks first to see if the problem is resolvable from your side!

Best,

Parker Dodson

1. Our system is as follows. One side is a MMI controller, the other side is the main controller. The failed RS485 IC is on the main controller.

2. Under normal condiction, the MMI Controller sends a command data to the main controller, the main controller receives the command data, and then replays the data to the MMI controller.  We can confirm the main controller has received the command, and replays the data. But no data appear on the RS485 bus.

3. The signal(yellow line) of the RX pin on the RS485 IC is as follows. So, we can confirm the MMI controller sends the data to the main controller successfully.  

4. The signal(yellow line) of the TX pin on the RS485 IC is as follows, and the blue line is the signal of the P6_1 (DE).  So we can confirm the main controller has sent out the data, and the DE is high.

But the A pin of the RS485 IC(as the blue line ) doesn't appear any signal. 

4. We explain our problem as above. Can you help me how to improve the problem?

Hi,

So to verify - DE is high on the main controller when you are trying to send a signal to the MMI Controller correct?

Below are some questions/steps that I suggest you follow to help isolate the problem. 

1.Are All the failures are occurring on the Main Controller Board?

2. If yes - have you looked at date-codes for failed IC's compared to the MMI controller IC date-codes? If they are the same this would lead me to believe that there is some transient causing issues on the main board that could be causing EOS damage to the IC. 

3. If the part markings are similar - you can report them to me and I can check our database if you are unsure - is there anything that has changed in the main controller design?

4. If the part markings aren't similar - once  again if you are unsure please let me know and I can look them up - the next step would be to return the suspect units for failure analysis so we can take a look into the quality aspect - more information on this process can be found here: https://www.ti.com/support-quality/additional-information/failure-analysis.html 

If you want me to check the part markings between the MMI controller IC's and the Main controller IC's I will - This does stick out to me that only the main controller is failing and not the MMI controller so I'd like to know the part markings here.

Please let me know.

Best,

Parker Dodson

1. DE is high on the main controller when you are trying to send a signal to the MMI Controller correct?<--Yes  

2. Some time ago, the 33 pieces of the RS485 IC are failed. The 24 pieces are on the main controller, and the 9 pieces are on the MMI controller.  The date-code of these ICs are "16K"。 At that time, we don't check the problem with great attention.

3. Recently, we get some failed ICs. These are all on the main controller. The marks on these chip are "VP3085 0BK C1LL G4" 

 4. We will contact the TI distributor, and return the failed ICs. 

Hi,

Alright - I agree I think sending the units to the TI distributor will help uncover some possible issues since due to failures on both systems. When you get results back and if you have any other questions please let me know and I will see what I can do. 

I am closing this thread for now - if you get results back before E2E locks the post (I think its after around 30 days) you can ask your questions in this thread - but if the thread locks please start a new thread and you can reference this post. I handle most of the RS-485 questions so I will be able to handle any  further questions.

If you have any other questions in the mean time please let me know!

Best,

Parker Dodson

Dear Parker,

We contact our PCB supplyer.  The date-code "16K" ICs are provided by the Arrow Electronics Taiwan LTD.  But the salesperison told me that these "16K" ICs don't come from TI directly.  The "0BK " ICs are provided by the Conevo Electronics Ltd(Hong Kong).  In normal condition, our PCB supplyer will buy the TI products from the authorized TI distributor.  But when the products are in short supply, our PCB supplyer will buy them from a genernal retailer.  Under our condition, can we return these failed ICs by the Arrow Electronics? 

Thank you for your helps.