TPS82140: Vout setting equation results differs from suggested and Webench solutions

Leonardo Govoni

Part Number: TPS82140

Good morning,

I am using this DCDC and I find some problems in the configuration of the feedback resistors.

If I want to configure Vout = 1.8V using the equation given in the datasheet Vout=0,8V*(1 R1/R2)

I get R2=100k, R1=125k. But in the datasheet it is suggested to use 124k. The same says the Webench simulation.

The same thing happens with Vout=1.2V:
I get from the equation R1=50k, R2=100k, and from webench R1=49.9k.

Is it the equation correct? Which values should I trust/use?

thank you very much,
regards
Leonardo

over 6 years ago

0 Chris Glaser over 6 years ago

TI__Guru*** 142580 points

Hi Leonardo,

Webench chooses 'standard value' resistors instead of the exact result of equations. You will notice all values are very close to each other.

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

TI__Guru*** 142580 points

Hi Leonardo,

Did I understand your question correctly? Does everything make sense?

0 Leonardo Govoni over 6 years ago in reply to Chris Glaser

Prodigy 60 points

Hallo Chris,

Thank you very much for your quick answer!

Now I understood which is the problem.

Have a good day,

Leonardo

Power management

Power management forum

TPS82140: Vout setting equation results differs from suggested and Webench solutions