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LM317: Question about thermal information of LM317 package

Part Number: LM317

Hello guys,

One of my customers is considering using LM317 for their new products.

They have several questions about TO-220 package thermal information as the follows.
Could you please give me your reply for them?

Q1. LM317 datasheet(Ver SLVS044W) says that TO-220 package (KCS) R theta JA is 19 degree C/W.
       Could you please tell me how this thermal resistance data was measured?

       I found the following description in the datasheet.
      (1) For more information about traditional and new thermal metrics, see the Semiconductor and IC package thermal metrics application report.
       I checked this document but I couldn't find how to measure thermal resistance of TO-220. 

Q2. Is TO-220 package thermal information in the datasheet measured only LM317 without extra heatsink?

Q3. Is the thermal information measured with the package standing vertically on the board?

Your reply would be much appreciated.

Best regards,

Kazuya. 

  • Hey Kazuya, 

    Q1: The changed thermal information in datasheet aligns with JEDEC standard for thermal information. Below is the JEDEC standard board. 

    Q2: There was not an extra heatsink used to gather data. 

    Q3: The values in the data sheet come from the thermal models. 

    Let me know if you have any further questions. 

    Thanks, 

    McKyla