TPS7A3001 Transient PSPICE and TINA Model

Richard Elmquist

The model appears to work well, but it does not seem to be able to model Vout when Vin is removed. The voltage follows Vin even if large amounts of capacitance are used on Vout. It seems as if this model will not model the output properly as Vout should hold for a few msec at least. Is there a reason why the output does not “hold-up”? It seems as if the model has an issue accurately modeling this.

Please let me know if I am looking at this correctly.

Thanks for your help with this!

Richard Elmquist

over 9 years ago

0 Britt Brooks - Online Design Tools over 9 years ago

TI__Mastermind 41310 points

Richard,

Could you provide the .TSC that your are using?

0 Richard Elmquist over 9 years ago in reply to Britt Brooks - Online Design Tools

TI__Mastermind 45250 points

Britt,

I simply used the TINA transient model and changed the load and Cout. I then switched Vin on and off repeatedly. It seems that no matter what values I use Vout always follows Vin and with a large cap load this should not be the case. Am I wrong here? Is this enough information?

Thanks for your help with this!

Richard Elmquist

0 Britt Brooks - Online Design Tools over 9 years ago in reply to Richard Elmquist

TI__Mastermind 41310 points

Richard,

I agree that the output drops very quickly when the input is taken away. I do not think that the actual device would drop off that quickly. When I put in a 1F cap, it discharges very slowly, but that is a ridiculous amount of capacitance.

I think that the LDO model is forcing the output to 0 when the input is removed. Perhaps a better test would be to put a time varying switch in the output node before the output capacitor and simulate it with that interrupt a few times. Take a look at the attached .TSC file to see what I mean.

This should eliminate the model from the simulation effect and let you tune the output capacitance based on how long the input voltage is taken away. The load will effect this as well... You can adjust the switch timing in the properties of the switch. I am waiting until the device reaches it's full output voltage before opening the switch.

Let me know if this helps.

TPS7A3001_interrupt.TSC

0 Richard Elmquist over 9 years ago in reply to Britt Brooks - Online Design Tools

TI__Mastermind 45250 points

Britt,

The example is great and odes seem to simulate the output when Vin is switched off.

I will send this to the customer.

Thanks so much for all of your help!

Have great day!

Richard Elmquist

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TPS7A3001 Transient PSPICE and TINA Model