OPA333: TI Precision Labs - Op Amps: Stability 1

d_zero

Part Number: OPA333
Other Parts Discussed in Thread: TINA-TI,

Dear *,

i tried to recreate OPA333 capacitive load 1u instabiliti in TINA-TI without success where is the problem?

Page 3 https://training.ti.com/sites/default/files/understanding-opamp-stability-intuitively-and-with-spice-simulations.pdf

1) When i use OPA333 model from the Spice Macros OpAmp and run the transient analysis i get this error:

2) i downloaded and copied the model to my design

SBOC083F.TSC (318 KB) - TINA-TI Reference Design

but i can't get the graph OpAmp_OPA333_Stability.TSC

Where is the problem?

Best Regards.

over 4 years ago

0 kai klaas69 over 4 years ago

Guru 140200 points

Hi d_zero,

your simulation file works for me:

d_zero_opa333_kai.TSC

Kai

0 Raymond Zhang1 over 4 years ago in reply to kai klaas69

TI__Guru 53641 points

Hi d_zero,

Your Tina model works as Kai indicated.

Please use Kai's Transient Analysis window setting (run up to 10msec and use Zero initial values) and you should see the instability or oscillation, because there is Q at approx 6.7kHz and does not have adequate phase margin (If you have a Q located at or near unity gain bandwidth, the op amp will oscillate, and this circuit demonstrate that concept).

Best,

Raymond

0 kai klaas69 over 4 years ago

Guru 140200 points

Hi d_zero,

is your simulation running now? Have you found the mistake?

Kai

0 d_zero over 4 years ago in reply to kai klaas69

Genius 4660 points

Hi Kai,

yes i had to select use Zero initial values instead of calculate operating point.

Br.

0 kai klaas69 over 4 years ago in reply to d_zero

Guru 140200 points

Oh yes. Thanks for the feedback :-)

Kai

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OPA333: TI Precision Labs - Op Amps: Stability 1