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LM317MQ: linear regulator thermal transient impedance

Alfred MOREL
Prodigy 10 points
Part Number: LM317MQ

Tool/software:

Hi,

I use the reference LM317MQDCYR (SOT223 package). A 135mA load must be supplied during 100ms.

Is existed a transient thermal impedance coefficient as power MOSFET? Or can we consider only the thermal resistance specified in the datasheet?

The thermal impedance is about 60°C/W

The drop voltage is about 10V. 

Maximal junction temperature is 134°C for 125°C specified for 55°C ambiant temperature. 

is it ok for a short duration or is it forbiden?

thanks for your help,

Best regards,

  • 0
    TI__Genius 15125 points

    Hello,

    Thank you for your thermal question.

    I calculated an operating temperature of 136 degrees C. (0.135A x 10V) = 1.35 x 60 = 81 +55 = 136 deg C

    Max recommended operating temperature is 125 deg C, therefore if you exceed this operating temperature then we cannot guarantee the electrical characteristics table.

    Best,

    Hannah