OPA690: Power rail question.

Li Wang

Part Number: OPA690

Can I power this OPAMP with +10V and -1V? , trying to use it to drive a load cell circuit and trying to avoid the cross over distortion by adding a small negative bias.

over 1 year ago

0 Clemens Ladisch over 1 year ago

Guru 243120 points

Yes. From the OPA690's point of view, +10 V / −1 V is the same as 11 V or ±5.5 V.

0 Michael Steffes over 1 year ago

Guru 47485 points

Crossover distortion? there is no crossover in the input stage of the OPA690?

0 kai klaas69 over 1 year ago

Guru 140200 points

Hi Li,

because the OPA690 has a rather limited input voltage range and output voltage range, the key question here is what input voltage range and output voltage range you desire.

Kai

0 Li Wang over 1 year ago in reply to kai klaas69

Prodigy 40 points

Hi kai,

the input voltage is 0V to 1V,

0 Alec Saebeler over 1 year ago in reply to Li Wang

TI__Genius 11545 points

Hello Li, thank you for providing the input voltage of 0V to 1V. I will take a look as well.

Best,

Alec

0 Li Wang over 1 year ago in reply to Michael Steffes

Prodigy 40 points

Maybe I didn't describe it correctly.. the main reason is we want the opamp to output true 0V when it can... when it is negative voltage input is connected to GND, it cannot output to GND.. that's why I am consider a -1V rail.

0 Alec Saebeler over 1 year ago in reply to Li Wang

TI__Genius 11545 points

Hello Li,

Just to clarify, you need the output to be 0V, which necessitates a split supply configuration?

The datasheet recommendation of +/- 5V supplies would correlate to a -1V and +9V supply. Since the device can accept a 12V total split supply voltage range, this configuration (and your -1V to +10V) are valid.
However, your common mode input range and output swing limitations will make it more difficult to achieve a 0V output on a -1V supply.

The minimum available output swing on +/- 5V split supplies is +/- 3.6V. The amplifier is swinging up to 1.4V from the supply rails. Knowing this, a negative supply voltage of -1.5V would be sufficient, swinging ideally up to 7.5V. You can stretch the positive supply to 10V, but your input common mode ranges and output swing available may shift due to the imbalance; the mid supply voltage shifts from 3V up to 4.25V.

Please look over the datasheet and provided curves to analyze the best supply configuration. If there are other design needs in addition to needing to output 0V at the output, please let me know.

Best,

Alec