TPS61169: Vfb has different spec in datasheet, why?

mick lei

Prodigy 30 points

Part Number: TPS61169

VFB = Duty x 204 mV; while duty=20%, VFB=20%*204mV=40.8mV;

But from below pic, while duty=20%, VFB=50mV;

I know VREF is from 188~220mV, type voltage is 204mV, but it still has big difference to below pic.

So, I want to know, why both spec are not the same? Which spec I need to refer?

over 6 years ago

0 Sean Zhou over 6 years ago

TI__Mastermind 22745 points

Hi Mick,
You should refer to this "Figure 1" for the FB voltage calculation. Because the relationship between duty cycle and FB voltage is not very linear and there is an offset which is used for low duty cycle.
Regards
Sean

0 mick lei over 6 years ago in reply to Sean Zhou

Prodigy 30 points

Dear Sean,

Thanks for your reply.

From your suggestion，which duty cycle section do you prefer us to use？ 10%~90% duty cycle？ or other？

0 Sean Zhou over 6 years ago in reply to mick lei

TI__Mastermind 22745 points

Hi Mike,
Actually I can't provide the suggested duty range for you, Why you need this kind of very strict linear relationship between duty and current? 10%-90% is a good choice. And Could you help to click "Resolved" for me? Thanks.
Regards
Sean

Power management

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TPS61169: Vfb has different spec in datasheet, why?