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TPS63700: Virtual Junction Temperature

Part Number: TPS63700
Other Parts Discussed in Thread: TPS65130


The datasheet makes reference to a "Virtual Junction Temperature".    What does "virtual" mean in this statement?   I don't think I've come across this in other datasheets.


  • Hi Don,

    the EC table is only specified to 85oC. The 125oC should be verified by simulation and bench test. in the right side of this page, there are many similar questions about the virtual junction temperature. 

  • Thanks Jasper,

    Per the datasheet the EC table specs 125oC for the junction temperature:

    I like the answer from this thread the best:

    Specifically it states:

    • "Virtual Junction" is a JEDEC standard term and is defined as,

      The theoretical point or region in a simplified model of the thermal and electrical behavior of a semiconductor device at or in which all the power dissipation within the device is assumed to occur.

      In plain English, the virtual junction temperature assumes that the temperature of the die in an IC is constant across the die, and that there are no hotspots. In a power device, this is not 100% true, but it is close enough for most practical purposes and makes thermal calculations much easier.

      If the junction temperature remains below 125°C, the TPS65130 device should operate correctly. However, if the ambient temperature of the application is 110°C, please make sure that the thermal design is done properly and is fully tested during development. With an ambient temperature so close to the absolute maximum rating of the device, you don't have much margin, so you must be sure that the device temperature is properly controlled. I strongly recommend you make thermal measurements under worst-case conditions to make sure the device temperature stays below the maximum allowed.

    To quote JEDEC here:

    • virtual-junction temperature; internal equivalent temperature (TJ; TVJ)

      (1) A temperature representing the temperature of the junction(s) calculated on the basis of a simplified model of the thermal and electrical behavior of the semiconductor device.

      NOTE The term "virtual-junction temperature" is taken from IEC standards. It is particularly applicable to multijunction semiconductors and is used to denote the temperature of the active semiconductor element when required in specifications and test methods. The term "virtual-junction temperature" is used interchangeably with the term "junction temperature".

      (2) The temperature of the virtual junction.


      JESD51-1#, 12/95
      JESD77-B, 2/00
      JESD282-B, 4/00

      JESD99B, 5/07