TPS7A94: Much longer startup time in simulation with 4.7uF Css

diverger

Part Number: TPS7A94

Hi,

In the 1A PSpice transient model (SBVM988), I change the Css to 4.7uF, and run the simulation, the Vout ramp time goes to hunderds of ms, which is dramastically different from the value give in the DS. Where is wrong?

Thanks.

3 months ago

0 Alex Davis 3 months ago

TI__Mastermind 19970 points

Hi diverger,

Can you attach an archived copy of your PSpice design? If so, I'd be happy to help troubleshoot.

Best Regards,

Alex Davis

0 diverger 3 months ago in reply to Alex Davis

Expert 1520 points

Hi Alex,

I've PM you the simulation project.

Thanks.

0 Alex Davis 3 months ago in reply to diverger

TI__Mastermind 19970 points

Hi diverger,

This appears to be an issue with the TPS7A94 model - the released model on ti.com does not model the fast charge circuit. We plan to address this in a future release, but unfortunately cannot give an exact timeline on when an updated model will be available.

Best Regards,

Alex Davis

0 diverger 3 months ago in reply to Alex Davis

Expert 1520 points

So, we can rely on the calculation of start-up time in the DS, right?

Thanks.

+1 Alex Davis 3 months ago in reply to diverger

TI__Mastermind 19970 points

Hi diverger,

Correct. The datasheet formulas will accurately calculate the startup time. Because the PSpice model does not incorporate the fast-charge circuit, the simulated startup time in PSpice will be longer than expected.

Best Regards,

Alex Davis

Power management

Power management forum

TPS7A94: Much longer startup time in simulation with 4.7uF Css