TJA1100 MDI interface failing

cancel
Showing results for 
Show  only  | Search instead for 
Did you mean: 

TJA1100 MDI interface failing

778 Views
lukemorton
Contributor I

Hi,

I am using the TJA1100 PHY in a hardware configuration as described in v0.2 of the AH1310 application hint, that is:

Connector -> 100nF series capacitor -> common mode choke -> TRX_P and TRX_M pins of TJA1100, with series termination and a TVS diode on the connector side of the capacitor.

With this arrangement, the device usually works fine, but I have been finding some cases where the TRX_P and/or TRX_M lines have shorted to ground, and the device no longer works correctly.

I notice that later versions of the AH1310 application hint suggest different hardware arrangements between the connector and the TJA1100, for example adding ESD protection on the TJA1100 side, and adding a low pass filter between the common mode choke and the TJA1100. Is all this needed, or could it relate to the issue I'm seeing?

It's worth noting that I have been unable to duplicate the problem by deliberately exposing the circuit to an ESD event, or by hot-plugging the connector.

All of the failures I have seen up to this point are with boards that have been known to work in the past, and suddenly stopped working (many, possibly all, while in use).

Thanks,

Luke

Tags (1)
0 Kudos
0 Replies