TFP410-EP: EMI issue

Hi Matt,

That link leads to an internal forum not accessible to people outside of TI. The only reply is below:

and there's no further replies.

Are you experiencing a similar issue?

Regards,

I.K.

Hi I.K.,

Yes, I'm experiencing a similar issue.  We have the following questions:

1. Are there any similar parts (pin compatible or otherwise) that would have reduced EMI levels?  We are running the DVI interface with a source clock frequency of 28.9MHz.
2. Does TI have any recommendations for how to deal with EMI issues related to this part (or DVI interfaces in general)?

Thanks,

Matt

Hi Matt,

Sorry for the delay.

1. The only pin compatible part is the TFP410 but I expect the EMI performance to be the same. 

2. I would recommend first focusing on the PCB layout and ensuring you're following proper layout guidelines: https://e2e.ti.com/cfs-file/__key/telligent-evolution-components-attachments/00-138-01-00-00-10-65-80/Texas-Instruments-HDMI-Design-Guide.pdf 

You can also try using the low swing mode of the device. Additionally, DVI/HDMI common mode chokes can be employed on the DVI lanes and small damping resistors placed on the parallel interface to slow down the edges. 

Regards,

I.K. 

Thanks for this information I.K.  The EMI is being emitted from the DVI outputs.  I don't know if EMI on the parallel interface (TFP410-EP input) will affect the TFP410-EP DVI outputs, but we will examine this.

I was looking through the datasheet and found that RTFADJ affects the output voltage swing.  According to the datasheet (absolute maximum ratings), it can be adjusted between 300 ohms and open.  We currently have it set to 510 ohms per the recommended value for DVI compliance.  Can TI provide a table to show how the voltage switch changes with RTFADJ?

Thanks,

Matt

Hi Matt,

Figure 6 in the TFP410 datasheet shows the relationship between Rtfadj and Vswing. I expect this to be the same for the TFP410-EP.

Regards,

I.K.