TAS3251: Internal electrical connection of PowerPAD

Hi Sydney,

Thank you for the reply. I understand where your comments come from as it is stated in the datasheet.

About electrical connection:

Sydney Northcutt said:

The heat sink should have a good connection to board ground. I don't recommend leaving it electrically floating.

The thermal pad that was applied to was not conductive and was thick enough that no electrical connection was made.

Customer was able to confirm fine IC operation without electrical connection on the pad on the EVM. Also, pin test showed there was no electrical connection between the pad and pins. (can you confirm this?)

They would like to use similar condition as EVM where the heatsink is not electrically connected. (the heatsink will have enough power dissipation.) Will there be any harm in the IC?

About thermal dissipation:

Sydney Northcutt said:

Having a good connection to the board ground will have additional help with thermal dissipation. 

I understand connecting the heatsink to the gnd increases the heat dissipation. Thank you for your comment.

Thanks,

Luke

Hi Luke,

The customer can do this if they verify it is okay with their design, but it can introduce large EMI issues. As long as thermals are taken care of the IC will still operate normally but I don't recommend doing this. If there is not any heatsink-PCB ground connection then this heatsink is electrically floating and any noise at device thermal pad will coupled to the heatsink via parasitic capacitance. Then this heatsink becomes a huge antenna and results in EMI problems. 

I am checking internally on the internal connection of the thermal pad.

Regards,
Sydney Northcutt

Hi Sydney,

Thank you for your comments.

Understood about connecting the heatsink to GND.

Please let me know if you find anything about the internal connection of the thermal pad.

Thanks,

Luke

Hi Luke,

Sure no problem. Yes I will keep you posted when I find out this information. 

Regards,
Sydney Northcutt