LT1013: LT1013

Kaveh Mohammad

Part Number: LT1013
Other Parts Discussed in Thread: TLE2021, OPA237, LMC6001, TLV2262AM

I am simulating below integrator using LT1013.

The simulated output waveforms Vout of OPAMP settles on 1 V while in practice it settles on 0 V. What is wrong here? is this because the model is old? what is the solution?

6201.Integrator.TSC

over 5 years ago

0 kai klaas69 over 5 years ago

Guru 140200 points

Hi Kaveh,

has it to do with this thread?

e2e.ti.com/.../780510

Why not raising the question this thread?

Kai

0 Kaveh Mohammad over 5 years ago in reply to kai klaas69

Intellectual 585 points

It looks like this question is getting too complicated and I am not getting any answer. I am trying to understand different pieces of the circuit.

0 kai klaas69 over 5 years ago in reply to Kaveh Mohammad

Guru 140200 points

Hi Kaveh,

you have got many useful answers in the other threads discussing your problem...

Kai

0 Kaveh Mohammad over 5 years ago in reply to kai klaas69

Intellectual 585 points

Well, I got directions on how to simulate the circuit for phase margin. But no solution end up with a reasonable justification of the source of oscillation. I still have problem simulating the circuit.

0 Thomas Kuehl over 5 years ago

TI__Guru* 93105 points

Hello Kaven,

The LT1013 simulation model is based on the legacy Boyle model, developed sometime in the 1970s, or 80s. It is very simplistic by today's standards and simulates a minimum of the op amp's electrical parameters. Models have evolved tremendously since the LT1013 Boyle model was developed, and they include many more of the electrical parameters providing much more realistic simulation results.

TI does not have a newer type model for the LT1013, but does have many newly built op amp models based on our latest, modern model design. The closest op amp to the LT1013 having a newly built bipolar op amp model, and having similar electrical specifications to it is the TLE2021. Because it has a much more sophisticated model it may help you analyze what is going on in your entire circuit.

You can find the TLE2021 model here:

www.ti.com/.../toolssoftware

Regards, Thomas
Precision Amplifiers Applications Engineering

0 Kaveh Mohammad over 5 years ago in reply to Thomas Kuehl

Intellectual 585 points

Thanks Thomas. Previously I was told to use TLV2262AM, OPA237, and LMC6001 instead.
Can you explain more in what terms TLE2021 is similar to LT1013 and better to use rather than the other ones? in terms of the location of the poles, frequency response, output current etc?

0 Kaveh Mohammad over 5 years ago in reply to Kaveh Mohammad

Intellectual 585 points

Even with TLE2021 the output of the OPAMP is settling on 0.75 V rather than 0 V.

0 Kaveh Mohammad over 5 years ago in reply to Kaveh Mohammad

Intellectual 585 points

Simulation with LMC6001 looks much closer to reality. Please see this thread: e2e.ti.com/.../2886751

0 Thomas Kuehl over 5 years ago in reply to Kaveh Mohammad

TI__Guru* 93105 points

Hi Kaveh,

That is because the high-voltage, bipolar op amps most often use an output stage design that prevents than from swinging any closer than several hundred millivolts, or even volts from the supply rails. The LT1013 and TLE2021 linear output swing is volts from the supply rails. Once the linear output range has been exceeded, the real op amp and its simulation model should enter into saturation at a specified voltage level. CMOS op amps such as the LMC6001 use a different output stage design that allows for closer swing to the supply rails.

Regards, Thomas
Precision Amplifiers Applications Engineering

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LT1013: LT1013