Maximum Op amp input voltage

[dirace]

50v a las entradas de opam

Hello
How can i determine what is the maximum input voltage that an Opamp can withstand regardles output Voltage?
I want to make an input stage tha can hold up to +/- 50 Volts
I dont know what to look for in datasheets

Thanks in advance

 

[nicleo]

voltage divider 50v to 5v

I dont know what to look for in datasheets

When you read datasheet, I think you should look for something as shown in the attached figure.

Regarding the +/- 50V input, is it possible to scale down the input voltage (e.g. using voltage divider) before opamp?

I did find out one ULTRA HIGH VOLTAGE OPERATIONAL AMPLIFIER:
**broken link removed**

 

[dirace]

max opamp input voltage

No I can not use a voltage divider before.
I will use +/-5V power supply,does this affect the Vin Max that the Opamp can stand?

 

[nicleo]

lm741 can be supplied 12 volts and -5 volts?

No I can not use a voltage divider before.
I will use +/-5V power supply,does this affect the Vin Max that the Opamp can stand?

Sure. It will affect the Vin Max of the opamp. If it's a rail-to-rail input opamp, the input voltage can be close to +5V or -5V.

 

[dirace]

Last question
Is it possible to have +/-50V Vin max with +/- 5V power supply?

 

[nicleo]

Last question
Is it possible to have +/-50V Vin max with +/- 5V power supply?

Without scaling, in my opinion, it's not possible.

You can test yourself. For example, you input a sinewave into an opamp, which is supplied by +/- 5V and configured as voltage follower. Then you slowly increase amplitude of the sinewave and when the amplitude is higher the 5V, the output will be distorted.

 

[dirace]

I dont want to amplify the signal i want to downgrade it.
Now i want to know if it is possible
1.To use +/- 5V power supply with an Opamp
2. Have an input signal +/- 50V downgrading it without distortion or destroing the Opamp.

Is this possible?

Thanks

 

[skydiverc]

By downscaling I assume you are wanting to reduce the input signal to some lower value. To do this just use a voltage divider network. like 10:1 that will cut your signal down to +-5V from +-50V.
It will not introduce any noise as it is passive. IT will change the signal to noise ratio though.

To maintain or attempt to maintain the signal to noise ratio

you can use a inverting amp with a input resistor that is 10x the feedback resistor you can apply the +-50V input signal to the input resistor.
By using a inverting amp you are placing a virtual ground at the - input of the op amp this will prevent overvolting the input to the op amp.
This will however invert the signal. if that is a problem use another inverting amp with unity gain. this will restore the phase relationship to the input.

 

[nicleo]

I dont want to amplify the signal i want to downgrade it.
Now i want to know if it is possible
1.To use +/- 5V power supply with an Opamp
2. Have an input signal +/- 50V downgrading it without distortion or destroing the Opamp.

Is this possible?

Answer:
[1] Why not? You can supply LM741 with +/- 5V.
[2] You will not destroy the opamp if you scale down the +/- 50V to say +/- 5V. Resistor is passive device. It should not distort the signal pass through it.

 

[suvendu]

no,you can not apply more than the d.c biasing voltage required for opamp.sice the 741 ic has maxinum biasing voltage is +-15v.if u apply more than this voltage at i/p .opamp become saturated.you can not get more than the saturated voltage.