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TPSM82480: Can we reduce the resister value for R1 and R2?

Part Number: TPSM82480

Hi Experts,

There is an explanation to calculate R1 and R2 as below.

It says that "A minimum divider current of about 5 μA is recommended and can be higher if needed." We want to reduce the resister value because we expect the noise on Vout(0.9V) is reduced due to smaller resister or higher current.

Does this understanding correct? Or is there no effect/advantage to reduce the resister value?

Regards,

Hisao Uchikoshi 

  • Hi Uchikoshi,

    your understanding is correct, By decreasing the feedback resistors value,  the divider current is increased, and therefor you have a better power to noise ratio.

    What values do you plan to use for the feedback divider?

    Regards

    Sabrina

    PS: This is currently holiday period please allow some delay in answering. We will get back to you latest on Friday.

  • Hi Sabrina,

    Thank you for your answer.

    We are planning to control the divider current between 5uA and 100uA. Is there any recommended current? 5uA enough? Additionally, are there any disadvantages for increasing divider resister excepts heat dissipation of resister?

    Regards,

    Uchikoshi

  • Hi Uchikoshi,

    the recommendation is to keep the divider current above 5uA. By increasing the resistive divider you are lowering the feedback current which. If the value is too it will decrease the signal to noise ratio which could cause stability problem for the regulation . Therefore please keep the divider current above 5uA

    In the following link are shown different considerations regarding the resistive feedback divider.
    www.ti.com/.../slyt469.pdf

    Regards

    Sabrina