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TMS320F28062: Ambient temperature of TMS320F2806x T version & S version different with TMS320F2803x

Vivian(MCU) Zhang
Intellectual 1545 points
Part Number: TMS320F28062
Other Parts Discussed in Thread: TMS320F28035

Hi,

Recently, my customer found that there's no specific data for ambient temperature of TMS320F2806x  T version  &  S version, only Q version have the data.

Datasheet like this:

But turn to TMS320F28035, there's data for all these three versions:

This confused both customer & I , for they belong to the same Piccolo series, should be the same, either ambient temperature or Junction temperature.

But from the datasheet , it obviously not the same. Please help explain the reason.

Vivian

  • 0
    TI__Guru* 95315 points

    Vivian,

                I checked with an expert in the team and he had this to say:

     

           "...Yes, as you have noted TMS320F2806x and TMS320F28035 are specified in different ways. For TMS320F2806x we do not specify ambient temperatures for T and S parts.  This aligns with our updated standard for specifying temperature grades.  The F28035 device was released before we updates updated our documentation standard.

           Ambient temperature is not the best method to use for system thermal design.  There are many other complex thermal interactions in a system which if ignored could lead to an incorrect conclusion if using only Ambient temperature.  Some factors are:

    • Number of PCB layers
    • Design of the thermal/ground plane and number of thermal vias
    • Location of other power IC’s in the system which can cause local heating through the board
    • System enclosures and airflow
    • Power consumed by the device through internal activity as well as IO switching and any resistive loads driven by the outputs.

     

    If an application is using any IC at near the top of its rated Junction temperature then care needs to be taken for all of these concerns.  The last item in the list (device power) can be used together with the Thermal Model information in the datasheet to find the temperature rise within the device package from either Ambient or Case temperature.  With the self-heating temperature rise the system designer can ensure the maximum rated junction temperature is maintained.

     

    As to why the Q parts specify Ambient, this is because the Q100 standard specifies ambient temperature in its definition of the different temperature grades..."