TPS7A88: Feedback Resistor Values

hideyuki sakai

Mastermind 6250 points

Part Number: TPS7A88

Dear, Sir.

My customer is considering to set the freedback resistor values, R1/R2, R3/R4, to

be more smaller values for the fine tuning of output voltage.

The datasheet described the current though R2, R4 > 5uA.

1) Is it no problem to set more smaller values, R1/R2, R3/R4 to maitain >5uA?

2) I suppose the side-effect would be current consumption through the resistor divider

network. I wonder it was correct?

3) If you find other side-effect or concern, Please let us know.

Please give your advice.

Best Regards,

H. Sakai

over 4 years ago

0 Stephen Ziel over 4 years ago

TI__Mastermind 29410 points

Hello Hideyuki,

I am working your question and will reply within 2 business days.

Thanks,

- Stephen

0 hideyuki sakai over 4 years ago in reply to Stephen Ziel

Mastermind 6250 points

Dear, Stephen-san.

Thank you so much for your kindly reply.

They are considering the review of resistor value for 3.3V output.

And the concrete value as candidates are below;

1) R1 / R2 = 7.5kohm / 2.4kohm

2) R1 / R2 = 75kohm / 24kohm

3)If you have more better combination, Please let us know.

Best Regards,

H. Sakai

0 Stephen Ziel over 4 years ago in reply to hideyuki sakai

TI__Mastermind 29410 points

Hello Hideyuki-san,

You are correct, it is no issue to use resistor values which provide larger current draws above 5uA.

If the customer wishes to use 0.1% tolerance resistors, then 2.4kohm and 7.5kohm are available.
If the customer wishes to use 1% tolerance resistors (E96 series) then the following may be acceptable choices:

R1/R2 = 9.31kohm / 3.01kohm, Vout_nom = 3.27V, Iout = 265uA

R1/R2 = 10.7kohm / 3.4kohm, Vout_nom = 3.318V, Iout = 235uA

R1/R2 = 35.7kohm / 11.5kohm, Vout_nom = 3.28V, Iout = 695uA

Thanks,

- Stephen

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TPS7A88: Feedback Resistor Values