Electronics > Beginners
Heating operational amplifier OP284FSZ-REEL7
DuPe:
maybe you are right wraper. But why then does it heat up that much?
wraper:
--- Quote from: DuPe on February 01, 2020, 08:52:26 am ---maybe you are right wraper. But why then does it heat up that much?
--- End quote ---
As minimum differential input voltage is exceeded. Once that's fixed, we can dig further. If op amp recovers from saturation poorly, it can increase heat dissipation. Transition can be happening with oscillations as well, adding some positive feedback can help with that.
Vovk_Z:
--- Quote from: DuPe on February 01, 2020, 08:32:34 am --- maybe I was not clear enough: Your circuit cannot work. You are torturing to death any op amp with this.
op amp is continuosly in open loop amplification and input overdrive.
--- End quote ---
Not any opamp but most of, you are right.
Jwillis:
wraper is correct.
If you look at the LM258W the Differential input voltage ca be as high as the supply voltage . The OP284 is only 0.6 V .
But your not totally in trouble because it also states "For input voltages greater than 0.6 V, the input current should be limited to less than 5 mA to prevent degradation or destruction of the input devices." Page 6 note 1 of maximum ratings . You can put series resistors on the inputs to limit the current . 1K should do the trick.
Glebiys:
@Jwillis, thank you for the answer!
I already created a board, so, unfortunately, adding a resistor at the moment will not work. This can be done in the next version of the board.
Then what are the options:
1) Change the value of the resistor on the voltage divider so that the voltage difference is in the range of 0.6 V.
2) Buy another operational amplifier that corresponds to a large difference in inputs.
The LM258W came up, but it's not Rail-To-Rail.
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