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TL074 gets hot !

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futurewave

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I figure out that the opamps in my circuit get very hot, The circuit is simple : 4 unity gain buffer using TL074 (-in=>out). The circuit has its normal electrical function but when I touch the chip surface I can feel a high temperature that is not normal to me. I have several instances of the same design on the PCB with the same behavior.

It is really strange because I moved my design on bread-board using DIP version of TL074 without any heat problem. The only difference now is that the SOIC version of TL074 is soldered on a well grounded PCB! I use +/-12 v on the rails + 100nF cermic caps close to the chip power pins.

Any difference between the DIP and SMD package of TL074?
Any Idea about the high temperature?

Tnx
 
Smaller package... Higher temperature. Define 'high temperature' because if you can touch it without removing skin from your finger it's not hot enough to damage the electronics. "Hot" is relative.
 
Smaller package... Higher temperature. Define 'high temperature' because if you can touch it without removing skin from your finger it's not hot enough to damage the electronics. "Hot" is relative.

I agree with Sceadwian :)

Also what loads are you driving? If you need voltage followers I presume you are driving low-ish impedance loads from a fairly high Z source.

Most op amps are unity gain stable - but that depends on what the load is. I have seen op-amps take considerable current (and hence get very hot!) on some student circuits where the op-amp was unstable (and oscillating). Some op-amps will go unstable when driving capacitive loads...

Maybe a good read

https://www.electro-tech-online.com/custompdfs/2011/07/00682c.pdf
 
Show the circuit first
 
it gets very hot when use 12v n 5 amps powersupply! Try to reduce amperage and post response.. My tl072 ic would get very hot and make hum when operate but i simply added a resistor to the '+' supply and the problems were fixed.
 
Smaller package... Higher temperature. Define 'high temperature' because if you can touch it without removing skin from your finger it's not hot enough to damage the electronics. "Hot" is relative.

The temperature is not so high to damage the chip, But from my point of view it is not normal for an opamp with minimum load.

Also what loads are you driving
no capacitance load. Actually it is not related to load I have tested it with output float and 10K ohm resistor to ground no difference.

Try to reduce amperage and post response.. My tl072 ic would get very hot and make hum when operate but i simply added a resistor to the '+' supply and the problems were fixed.

I'm not sure it is a good idea. Anyway power supply regulators are 78M12 and 79M12 that do not provide more than 0.5-1 Amps.

The circuit is actually a Multiplexed DAC + S&H stage , Here is the schematic:
 

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Despite your precautions with grounding and power-pin caps it's possible there may be circuit oscillation. Can you check with a scope ?
 
I checked it with scope, there is only a 5mVp-p AC ripple at the output stages which I think is a portion of power supply ripple. it does not sound like oscillation.

How an oscillating/unstable opamp should be ? Can it easily be traced with scope?

I planned to move from SOIC package to TSSOP due to size limit of my PCB. With my experience with SOIC I think a TL074 in TSSOP package will melt my PCB.
 
I saw the datasheet of a Japanese (Toshiba?) copy of a TL074 where they made it "better". They made it oscillate at a high frequency which made it hot. They recalled and replaced most of them. Maybe you have a bad copy. Use an American TL074.

A TL07x will oscillate when its output directly drives the capacitance of a couple of feet or more of shielded audio cable. It is fixed by adding a 100 ohm resistor in series with the output of the circuit so that the resistor drives the cable.
 
hmm this is interesting, cause I have some LM555CN timers that I got that have a max supply of 16 volts, but when powered even with twelve volts, they get warm, even during normal usage. They are in dip-8 packages.

-Ben
 
A 555 can supply 200 ma on it's output (pin 3) if memory serves me correct. It probably will get a bit warm if your drawing a fair current off it :)
 
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