OPA698: Limiting amplifier with OPA698 unipolar +5V supply, Output limit 0-2V, inverting

Dimitur Benchev

Part Number: OPA698

I need to use OPA698 as limit amplifier for ADC input. Unipolar power supply +5V, Inverting input (0-0.8 V DC input signal). Output limit 0-2V.. That is the diagram, I'm using. Output voltage is always 1.1V and doesn't change with applied input voltage. Please, advice. Thanks

Schematic_Detector2020_2020-06-04_10-28-13.pdf

over 3 years ago

0 Hasan Babiker31 over 3 years ago

TI__Genius 15555 points

Hello Dimitur,

You need to be wary of your input & output range limitations. In your schematic you are using the OPA698 in single supply, but your are setting your input common-mode range to GND. Note that in the datasheet, your input common-mode range is between 1.7V to 3.3V.

Also your output range will be from 0.9V to 4.1V.

In short, I recommend switching to a dual supply configuration, or offset your input/output by your midsupply voltage.

Best,

Hasan Babiker

0 Dimitur Benchev over 3 years ago in reply to Hasan Babiker31

Prodigy 20 points

Thanks, Hasan,

I will try that. Can you sketch the diagram for me? I'll keep you posted. Thanks

Best Regards

Dimitur

0 Hasan Babiker31 over 3 years ago in reply to Dimitur Benchev

TI__Genius 15555 points

Hey Dimitur,

Refer to the picture below:

Best,

Hasan Babiker

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OPA698: Limiting amplifier with OPA698 unipolar +5V supply, Output limit 0-2V, inverting