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TLV733P: thermal resistance

Shanoj G
Prodigy 150 points
Part Number: TLV733P

Hi,

I am planning to use TLV73333PDBVT LDO. As per datasheet Rth JA is 228 c/w. It is also mentioned junction to board thermal resistance is 55.8 c/w. I would like to know what is the preferred copper area i have to provide as my FR4 8 layer board is 1mm thick, in order to get this junction to board thermal resistance of 55.8 c/w. My input is 5V, load is 3.3v, 80mA. Just want to make sure case temperature rise to limit within 15 to 20C.

thanks,Shanoj

  • 0
    TI__Intellectual 1146 points

    Hi Sanoj,

    It's best if we estimate the maximum ambient temperature as a function of the Rth JA. In this case since you want to output 80mA, your power dissipated is 0.136W.

    In order to maintain your desired 15C temp rise we would need an Rth JA of ~110 c/w. So we need to address a 50% reduction in Rth JA form the datasheet value of 228 c/w. Gerard from our team recently published an application note covering this level of reduction. In his experiment he found an area of 10.5 in2 of connected copper and 8.43 in2 of disconnected copper, yielded a ~53% Rth JA reduction.

    Keep in mind that the dissipation impact is going to be directly impacted by the way the GND plane is laid out and by how it is connected. Here is a bit more information on the description of these boards we have used: http://www.ti.com/lit/an/slvae85/slvae85.pdf.