OPA2277 with single supply

Shrikant Lokhande

Other Parts Discussed in Thread: OPA2277, OPA2333, INA333

Hello all,

I have been using OPA2277 with dual power supply in my circuit and it works satisfactorily.

Now I intended to use it with single supply but on exploring the datasheet I couldn't get any information about single supply operation.

I require high precision in the output which is in milivolts. Will it affect the offset of the IC if used with single supply.

Thanks and regards,

Shrikant

over 14 years ago

0 Edwin Krasser over 14 years ago

Expert 2430 points

Hi,

single supply operation is not mentioned in the datasheet because this opamp (input and output) is not specified for single supply operation (input and output may get as negative as the negative supply).
Datasheet, page 3, input voltage range, common mode: VCM= V- +2V to V+ -2V (2 volts from rails)
Datasheet, page 4, output voltage range, RL=10 kOhm: V- +0.5V to V+ -1.2V

Best regards,
Edwin Krasser

0 Shrikant Lokhande over 14 years ago in reply to Edwin Krasser

Intellectual 655 points

Hi Edwin,

Thanks a lot for the quick reply.

Actually my input and output ranges are within the specified limit and my input will never go into negative but it will be in milivolts (a thermocouple signal).

I intended to use it as a unity gain buffer.

Will then it can be used with single supply or please recommend me the one with same pinout.

Thanks and regards,

Shrikant

0 Edwin Krasser over 14 years ago in reply to Shrikant Lokhande

Expert 2430 points

You want to buffer a very low level input voltage (some mV to GND). So you will need a single supply opamp with very low offset voltage. How about a OPA2333?

Best regards,
Edwin Krasser

0 Shrikant Lokhande over 14 years ago in reply to Edwin Krasser

Intellectual 655 points

Hi Edwin,

Thanks a lot again, I will check out the IC and let you know.

Thanks and regards,

Shrikant

0 Neil Albaugh over 14 years ago in reply to Shrikant Lokhande

Genius 5430 points

Shrikant;

For a thermocouple amplifier you may be better suited to an instrumentation amplifier. It has high common mode rejection and can provide high gain. One of TI's +5V CMOS amplifiers such as an INA333 may be your best bet.

0 Shrikant Lokhande over 14 years ago in reply to Neil Albaugh

Intellectual 655 points

Hi Neil,

Thanks for your valuable comment. INA333 would be great for thermocouple signal measurement.

I read your comment on EEG signal measurement and downloaded the draft copy "The Instrumentation
Amplifier Handbook " and it helped me solving some of my problems regarding instrumentation amplifiers.

Thanks and regards,

Shrikant

0 Jayant Deshpande over 14 years ago in reply to Shrikant Lokhande

Expert 1495 points

Hi Shrikant,

With INA333, you also get inbuilt RFI filtering!

The output swing is within 50mV of supply rails, though.. this might be critical in case you are expecting a near-zero output with single supply.

Regards,

JayantD

0 Shrikant Lokhande over 14 years ago in reply to Jayant Deshpande

Intellectual 655 points

Hi Jayant Sir,

For instrumentation amplifier I certainly need dual power supply and for OPA2333 I can manage with single supply.

Now I will have to make decision which one is more critical to me, but I'm glad to have two good options.

Thanks and Regards,

Shrikant

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OPA2277 with single supply