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TL084: Unused inputs and thermals

Jason Haedt
Expert 3230 points
Part Number: TL084

Hello,

I was running an experiment to look at thermals on the TL084.  When I take all four channels with a bipolar supply (+/-12V) and tie the inverting terminal to the output and the positive input to ground (0V) I am seeing temperatures on the TL084 of 50C.  What is the prefferred mechanism to tie unused inputs on the TL084.  

My air temperature is around 20C and is it expected to see 50C when I am using the PW package?  The thermal is 113C/W which means the 30 degree rise is .265 W.  

-Jason 

  • 0
    TI__Guru*** 140136 points

    Jason,

    Typical Iq is 1.4mA per channel. No load power dissipation would be 1.4mA/CH * 4CH * 24V = 134mW 

    The op amp connections that were described are good although no inputs should be directly tied to ground; a small series resistance (>1k) should be added to protect against power supply faults or improper power up/down.

    Thermal impedance, Tja, is dependant on board properties; Is the board temperature near the TL084 also 20C?