- #1
bphui
- 7
- 0
The output voltage of op amp is greater than the power supply voltage (+/- 5V). Is Op amp burned out?
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SUMMARY
The discussion centers on troubleshooting an op amp that outputs a voltage exceeding its power supply voltage of +/- 5V, indicating potential burnout. Users suggest checking the configuration of the power supply and grounding connections, particularly ensuring the negative terminal of the op amp is grounded correctly. The use of a 100MΩ feedback resistor with a 0.22μF input capacitor is identified as problematic due to a long time constant of 22 seconds, which can hinder stabilization. Participants emphasize the importance of reviewing the schematic for proper connections and grounding to diagnose the issue effectively.
PREREQUISITES- Understanding of op amp configurations and power supply connections
- Familiarity with voltage measurement techniques using a voltmeter
- Knowledge of feedback resistor and capacitor interactions in op amp circuits
- Ability to read and interpret electronic schematics
- Investigate proper grounding techniques for op amp circuits
- Learn about the effects of feedback resistor values on circuit stability
- Research the implications of time constants in RC circuits
- Examine common op amp configurations and their troubleshooting methods
Electronics engineers, hobbyists working with op amps, and anyone involved in circuit design and troubleshooting will benefit from this discussion.
- #2
BiGyElLoWhAt
Gold Member
- 1,637
- 138
Probably. Have you tried replacing it?
Is it of the order of one of your input voltages?
Is your volt-meter or sensor hooked up to v out and not to your inputs?
Do you possibly have it set up as +10/0V as opposed to +/-5V?
Is it of the order of one of your input voltages?
Is your volt-meter or sensor hooked up to v out and not to your inputs?
Do you possibly have it set up as +10/0V as opposed to +/-5V?
- #3
bphui
- 7
- 0
Yes, I have replaced it and the result is still the same.BiGyElLoWhAt said:
I also set the power supply to +5/0V, the output has negative voltage too.
I am connecting charge amplifier with pvdf film.
- #4
BiGyElLoWhAt
Gold Member
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- 138
What are you referencing as ground on your voltmeter? Is it the ground off of the power supply?
- #5
BiGyElLoWhAt
Gold Member
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Also, check the difference between your high and ground with a voltmeter.
- #6
bphui
- 7
- 0
Ground the negative terminal of op amp.BiGyElLoWhAt said:
- #7
berkeman
Admin
- 69,345
- 24,674
What other voltage is connected to the output. The output of the circuit cannot be outside of the power rails without some other power source pulling that point up.bphui said:
Can you post your schematic?
- #8
Averagesupernova
Science Advisor
Gold Member
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If the negative lead of the voltmeter is hooked to the negative supply when using a split supply setup I can see why you could get readings like this.
- #9
- #10
Svein
Science Advisor
- 2,316
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Your schematic does not show which pins you use to connect to the power supply.
- #11
bphui
- 7
- 0
p
pin 7 connect to +5v
pin 4 connect to -5vSvein said:
pin 7 connect to +5v
- #12
Svein
Science Advisor
- 2,316
- 813
Using 100MΩ feedback with a 0.22μF input capacitor is a recipe for trouble. The time constant is 22 seconds - so it will take forever to stabilize.
- #13
Averagesupernova
Science Advisor
Gold Member
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I noticed this too. The whole things looks a bit odd. Wondering what is connected to the header?Svein said:
- #14
bphui
- 7
- 0
The header connects with pvdf film.Averagesupernova said:
- #15
bphui
- 7
- 0
Is 100M feedback with 0.22uF and 1000pF?Svein said:
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