INA317: INA317: Series resistor at both inputs

Jagbir

Part Number: INA317

In the T I D A-0 1 0 0 1 9 schematic(page3) I see 10K resistors on both the inputs.Is this design choice just for current limiting on input pins?

http://www.ti.com/lit/df/tidrzc3/tidrzc3.pdf

over 5 years ago

0 Tamara M Alani over 5 years ago

TI__Genius 10850 points

Hi Jagbir,

Are you referring to R77 and R82?

-Tamara

0 Jagbir over 5 years ago in reply to Tamara M Alani

Expert 1525 points

Yes I am referring to R77 and R82.

0 kai klaas69 over 5 years ago

Guru 140200 points

Hi Jagbir,

they are not only for current limiting but also for low pass filtering in combination with C69, C70 and C73.

Kai

0 Jagbir over 5 years ago in reply to kai klaas69

Expert 1525 points

Thanks Kai !

What value is added to the design by R76 and R81. They could have easily been combined with R77 and R82.

0 kai klaas69 over 5 years ago in reply to Jagbir

Guru 140200 points

Hi Jagbir,

R76 and R81 are necessary to limit the current through the protection diodes D12 and D13. R77 and R82 provide a further current limiting caused by the rest overvoltage dropping across the protection diodes. R77 and R82 also provide a low pass filtering, as these resistors are dominating over R76 and R81.

Kai

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INA317: INA317: Series resistor at both inputs