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OPA4830 doesn't work
I bought operational amplifier OPA4830. TSSOP14 package with 4 operational amplifiers inside. Datasheet: here
1st - OP AMP I use as a summer
2nd - integrator
3rd - trigger
4th - voltage follower
I use +/- 5V power supply and when I turn it on, the chip become hot and strange sound comes from it. Also in Power supply display shows current consumtion: 0,11A!!!
When I use other OP AMPS in the same PCB, for example (LM324N), everything works fine, so in circuit there isn't problem.
How sure are you regarding the +/- 5V levels? The chip is designed to work with tight voltage, at +/- 5.5V at most (The LM324 range is larger).
Could it be that the device was damaged on another board and now it is not working anymore?
Are you completely sure regarding pin #1 position? Could it be that it was placed at 180 degrees rotation?
Sorry for asking silly questions, but I have seen this workmanship mistakes many times.
I use very good power supply, so I'm very sure about voltage levels:
I think the device couldn't be damaged, becouse I tested a few OPA4830 OP AMPs.
About pin #1 postion I'm sure, I checked it several times.
I think maybe there is problem with OP AMPs circuits, becouse, for example, I can't make voltage follower and integrating Op Amp circuits becouse of input resistance in current feedback Op Amps, it's too low (16ohm inverting input impedance). But OPA4830 isn't current feedback and it has 10k-400k ohm impedance.
So maybe there is something that I don't know?
From some simulations I did using TINA-TI and the 830 model, it seems there are problems using this opamp as integrator... but I don't understand why. Did you try to simulate your circuit?
I made all circuit in TINA-TI with OPA830, and simultation worked very well in Transient analysis. I'm new in this program, so what I should something else?
Also, why TI employers ignore this post?
Also I solder new PCB with OPA4830. First of all I added only power supply: U+ = +5V, U- = -5V. Everything seems to work well, except it consume 0,01A.
Then I added sumator. Everything ok.
Then integrator. It started to become a little hot at +/-5V, but it worked fine at +/-2,5V.
Then I aded comparator. Everything ok.
Then voltage follower and negative feedback to summator and it becomes rapidly very hot at +/-5V and all circuit consume 0,12A. When I use +/-2,5V it doesn't heat, but output is very noisy and seems it doesn't work like it should and like it was in simulations. Current consumtion - 0,08A.
Thanks for helping.
See the thermal information listed on page 6 of the OPA4830 datasheet. ΘJA = 95 °C/W. If you supply +/-5V with 10mA current draw with no external connections, then the device is dissipating 9.5°C. As you add extra circuitry around the device, the power dissipates through the external passive components and the ground plane. Using a lot of copper for the ground plane is a good way to dissipate this heat as well as picking larger passive components that are rated for higher power. Have you looked at the board with a thermal camera to see where the hotspots are?
As a check, you can upload your TINA schematic and we can take a look.
Regards,Luke LapointeHigh Speed Data Converters
I use 0402 components.
After looking at the circuit, I am not really sure what you are trying to accomplish. The connection from the output of the voltage follower back to the input of the first amplifier adds a large DC component (either the positive rail or the negative rail from the comparator) to your sine wave. This will cause the signal to bump against the input common mode range limits of the amplifier and clip, which will additionally cause the waveform to look very distorted and strange.
The second thing I notice is that in your comparator stage you have positive feedback, which is not neccessary for a comparator. Positive feedback is generally a source of instabillity and can cause strange problems in your circuit.
What is the purpose of this circuit?
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