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TLV755P: Guidance on Thermal Calculation for TLV755P (DYD Package)

Loganathan ravi
Prodigy 40 points
Part Number: TLV755P
Other Parts Discussed in Thread: TLV755EVM-087

Tool/software:

Hi TI Team,

I’m currently using the TLV755P in the DYD package for a 5V to 3.3V regulation application, with a load current of 400mA. As part of the design process, I’m performing thermal calculations for the LDO.

In the datasheet, I noticed two different values for RθJA:

  • EVM-based: 60.3°C/W
  • JEDEC standard: 92.5°C/W

Additionally, the datasheet specifies:

  • Absolute maximum junction temperature: –40°C to 150°C
  • Recommended operating junction temperature: –40°C to 125°C

Could you please guide me on which RθJA value is appropriate to use for thermal calculations in a real-world PCB layout?

Your support is greatly appreciated.

Regards,
Loganathan R

  • 0
    TI__Expert 5040 points

    Hi Loganathan,

    The RθJA value is a system level parameter and depends on the thermal impedances of the PCB it is placed on. Therefore, we have provided two values for two different boards. The JEDEC standard value is evaluated for a JEDEC standard board (JESD57-1), and the EVM value is calculated for the (now superseded) TLV755EVM-087. User guide here: TLV755EVM-087 Evaluation Module User's Guide. The EVM was deliberately designed to have improved thermal performance over the JEDEC standard 74.2mm square board which is why the value is lower.

    Some notes from a previous discussion regarding The JEDEC standard: 

    It is usually best to use the JEDEC standard RθJA (92.5'C/W) in the design phase. 

    Recommended operating conditions means that it will conform to the electrical characteristics table limits within that temperature range. Absolute Maximum ratings means that damage may occur past that temperature. Anywhere beyond the recommended operating conditions but still within Abs. Max. will operate without damage but is not gauranteed to conform to the EC table specs. It is usually best to use the upper recommended limit (125'C) as the temperature limit but regard it as a soft requirement.

    Best,

    Gregory Thompson