TPS82084: How to use EN pin as soft startup control?

Tiger Wang

Part Number: TPS82084
Other Parts Discussed in Thread: TPS82140

Dear Sir,

TPS82084 has a fixed soft startup time ,0.8ms(while EN is connected with VIN directly). I know TPS82140 has SS/TR pin ,can I use EN pin(tps82084) to adjust the soft startup time？(e.g. using R.C circuit )

Of course, the delay time is more then 0.8ms ,because we can not modify the fixed soft startup setting.

Best regards.

David

over 6 years ago

0 Chris Glaser over 6 years ago

TI__Guru*** 142880 points

Hi David,

It's not clear what your question is. Do you want to change the ramp time of Vout or the time from EN high to Vout ready?

This app note, found on the product page, has more details on this topic: www.ti.com/.../slyt669.pdf

0 Tiger Wang over 6 years ago in reply to Chris Glaser

Expert 1535 points

Dear Sir,

I had found a paper "slyt730-Achieving a clean startup by using a DC-DC converter with a precise enable-pin threshold", which tell me how to adjust the start-up time.

Thanks.

David

0 Chris Glaser over 6 years ago in reply to Tiger Wang

TI__Guru*** 142880 points

Hi David,

Yes, that one also discussed this topic. But neither of these devices has an accurate EN pin, so that method is not a robust one.

You can use the PG pin of the upstream DC/DC to delay the turn on of the next module.

It seems like you do refer to the delay time, before Vout starts to ramp up.

0 Tiger Wang over 6 years ago in reply to Chris Glaser

Expert 1535 points

Dear Chris,

Yes, I just want to adjust the sequence of power startup, although its EN is not accurate,it is enough.

Thanks a lot.

Best regards.

David

Power management

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TPS82084: How to use EN pin as soft startup control?