TCAN1051HGV: ACK ERROR

Hi Gareth,

It looks like there was signal integrity issue due to the ringing on the bus, and thus caused the glitch on RXD to receive an error bit. This kind of communication errors in systems can by caused with higher data rates, large physical bus topologies, etc. Did the customer put common mode choke and terminate bus properly? 

Regards,

Sean

Hi Sean

1.Could you help check the below TCAN1051 schematic and any need to adjust

2.Where is the recommended common mode choke to be added? Should it be added to every NODE?

Hi Gareth,

Looks like they are not using CMC so placing it between transceiver CANH/L pins and the termination resistance would be helpful to reduce the ringings.

The image is not clear, what are those two resistors on the bus? Terminations or series resistance? Or just DNP?

Regards,

Sean

Hi Sean

The schematic is updated as follows

Hi Gareth,

The schematic looks fine, but we still recommend to use common mode choke to solve that ringing issue on the bus (which caused the ACK error). CMC can be placed somewhere like below:

Regards,

Sean

Hi  Sean

Hi Gareth, 

There are many transceiver factors that impact ringing, most of which are bus driver characteristics. These include paracitics such as capacitance as well as driver behavior such as ringing suppression technique, timing, and drive strength. Typically these are very similar between similarly specified transceivers, so the main way to improve signal quality will be to simplify or modify the bus harness or change to a different class of transceiver (such as a CAN SIC device for improved ringing suppression). 

In this case it looks like the addition of a common mode choke would help improve the signal quality in them system. I've linked an application note below that goes over some of the details of CMCs and includes various part numbers that may be suitable for your application. 
https://www.ti.com/lit/an/slla271/slla271.pdf?ts=1676993696425&ref_url=https%253A%252F%252Fwww.google.com%252F 

Regards, 
Eric Schott