OPA4322: Output saturation on TINA-TI

Michiaki Tanii

Part Number: OPA4322
Other Parts Discussed in Thread: TINA-TI, OPA4376

Hi,

Our customer is considering adder circuit with OPA4322 and simulated with TINA-TI but saturation was seen saturation as following.

Their requirement is

- Add offset 1.65V for Sin wave Vp-p : 3.3V

When OPA4376 was used, saturation for output was not seen.

Could you kindly advise on the following.

- What is the difference for the result of simulation between OPA4322 and OPA4376 ?

- Why was the phenomenon seen ?

- How to design circuit for their design ?

Thank you and best regards,

Michiaki

over 5 years ago

0 Bala Ravi over 5 years ago

TI__Expert 6625 points

Hi Michiaki,

Can you please attach your TINA-TI file to this thread?

Best Regards,

Bala Ravi

0 Michiaki Tanii over 5 years ago in reply to Bala Ravi

TI__Expert 4600 points

Hi Bala,

Please find the attached file.

OPA4322.TSC

Thank you and best regards,

Michiaki

0 Bala Ravi over 5 years ago in reply to Michiaki Tanii

TI__Expert 6625 points

Hi Michiaki,

Please note that our responses may be delayed due to holiday season. We will get back to you as soon as we can.

Best Regards,

Bala Ravi

0 kai klaas69 over 5 years ago in reply to Michiaki Tanii

Guru 140200 points

Hi Michiaki,

you use a macro model of OPA4322 from 2011 in your simulation which is not up to date. There's a newer model in the "TINA-TI reference design" of this OPAmp available. See here:

You can even go some closer to the supply rails when increasing the output load resistance of OPA4322 from 2k (R2 + R3) to 10k or above:

Take also care: The +input of OPAmp goes negative for a brief period. Because of this the negative half waves at the output of OPA4322 are flattened when reaching 0V.

michiaki_opa4322.TSC

Kai

0 Bala Ravi over 5 years ago in reply to kai klaas69

TI__Expert 6625 points

Hi Michiaki,

Please follow Kai's comments above.

Even with the updated model you will run into clipping of the output. This is due to output swing limitation. Please refer to the output swing limits from the datasheet. Output swing is in reference to your supply voltage. One easy way to fix it is to have your supply at about 100mV higher than your expected output. This will take care of your output from clipping.

Best Regards,

Bala Ravi

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OPA4322: Output saturation on TINA-TI