UCC21750-Q1: uncorrect behavior on RESET under tFLTMUTE in PSPICE

Chuqiang Wen

Part Number: UCC21750-Q1
Other Parts Discussed in Thread: UCC21750

Tool/software:

Hi Expert,

My customer is using UCC21750 Unencrypted PSPICE Transient Model to do the simulation. They are trying to simulate the sequence show below.

They found a problem that UCC21750's nFLT can be reset under tFLTMUTE period. Could you please help check if this behavior make sense in PSPICE model?

Thanks!

Ethan Wen

3 months ago

0 Sean Cashin 3 months ago

TI__Mastermind 23206 points

Hi Ethan,

Here is a version of the PSPICE Model where the nRST function has not been included. That will prevent the nFLT from being reset during the tFLTMUTE period.

Best regards,

Sean

1004.UCC21750.zip

0 Chuqiang Wen 2 months ago in reply to Sean Cashin

TI__Expert 5865 points

Hi Sean,

I shared this PSPICE model to BYD. But they feedbacked that it is still work abnormally. See below the waveform. There have labels at each bottom side of waveforms.

You can see that DESAT is always at 14V which cause UCC21750 cannot turn on output correctly. Could you check if it is aligned with your result?

Thanks!

Ethan Wen

0 Sean Cashin 2 months ago in reply to Chuqiang Wen

TI__Mastermind 23206 points

Hi Ethan,

Can you share their PSPICE simulation file? They may simply need to short DESAT to COM to observe a typical output response.

Best regards,

Sean

Power management

Power management forum

UCC21750-Q1: uncorrect behavior on RESET under tFLTMUTE in PSPICE