Chip is getting warmer

Hi,

Can you tell why an IC might get warmer even if you stay far away from your rated voltage? I asked something close to this for max414cpd before. Probably, the chip is not the issue because i tried giving 10v to two different identical ICs . Both gave me the same problem? In the datasheet it states that I can give 10v.

Thank you a lot.

Hi,

* P generates heat
* P = V x I.
* V is known (10V)
--> measure I
then you will know ho much the device consumes.

Datasheet says supply current should be about 2.5mA.
The output of the OPAMP drives a load. It consumes additional power. You have to take care about that current in your overall power calculation.
How much heat this additional current will produce at the OPAMP depends on load voltage.

***
BUT maybe your OPAMP is oscillating, then you have increased heat generation in the IC.
--> read datasheet how to design a stable OPAMP circuit.

Generall rules:
* Don´t leave any unsued input floating. (not with analog ICs, not with digital ICs).
* use a solid GND plane
* use ceramic capacitors at each supply pin of each IC. Short, low impedance wiring.

Klaus

KlausST said:

Hi,

* P generates heat
* P = V x I.
* V is known (10V)
--> measure I

Click to expand...

You want to see a part get warm, then try this with a large FPGA running at 300 MHz where the power consumption is on the order of 25 W (typical) or more in a package that is 36x36 mm. Without a heat sink that sucker can burn your finger. I've used JTAG to monitor a V7 FPGAs internal temp sensor and seen that thing go from 22 C (the ambient lab temp) to over 70C in a mater of minutes after loading my code, I informed the board designer that it needed a heat sink and a fan to blow over it if they wanted me to test my code on the FPGA. After that it ran at a nice warm 45C.

Try increasing the output impedance which will lower the current and OP-AMP will not heat up.
If the OP-AMP in any circuit is heating, the circuit or PCB or both have problem.
Always try to match the impedance from output.
The best way to match impedance is use voltage follower or buffer circuit between each block of circuit. This will increase the quality and performance of the circuit.

I asked the schematic to someone else but i couldnt fix the issue, so I want to ask to u too. How can i modify the circuit which I attached below? it is input is connected to 50 ohm system, its output is connected to input of audio port of the computer? There are some resistors which are additional to classical sallen key topology, might they be used for impedance matching?

Thanks.

Especially, 47kohm at the end? Might it be used for impedance matching?

Hi,

Don't guess, do what I've recommended in post#2
--> measure I

Klaus

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Added:

According your schematic...you run the MAX414 with 12V.
This is the absolute maximum value. This is not the recommended value of +/-5V, or 10V.
Any voltage above 12.0V is out of specification and may cause damage. Like 12.1V. Or any spike, any overshot at power-up.

Then you use 5V as reference. Is it stable (when excited with 0Hz ...28MHz)? Is it able to source and sink currents without oscillating?

Klaus