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TPS3620: On the divider resistance of PFI pin

Masazumi Ishii
Genius 3945 points
Part Number: TPS3620

Hello

I have a question about TPS3620.

How much is the voltage dividing resistor range connected to PFI pin?
Is resistance connection possible from 10 MΩ to 20 MΩ?

Thank you.

  • 0
    TI__Expert 3835 points

    Hi Masazumi,

    I do not recommend making resistor dividers add over 1 Mohm. See text below I took from the datasheet regarding the PFI pin. Since there is no specification on the datasheet, we cannot guarantee if it is possible or not. I will ask the internal team to get some more information.

    Hope this helps,

    Ethan

  • 0 in reply to Ethan T
    Genius 3945 points

    Hello.

    thank you for your answer.

    I want to increase the resistance value of PFI because the system wants to extend the life of the battery because it is battery operated. (We are taking noise countermeasures with capacitors.)
    Can you figure out because I want to send the circuit diagram?
    Please tell me your e-mail address. I will send it.

    Thank you.

  • 0 in reply to Masazumi Ishii
    TI__Genius 12630 points

    Masazumi,

    The input current into the PFI pin is spec'd in the datasheet in the Electrical Characteristics table at 25nA. If this is suitable, no additional resistance is required.

    As you increase you resistor values, the current will go down, but the accuracy will also get worse. Please see this detailed app note that explains the trade off between resistance and current and accuracy for resistor dividers at comparator inputs.

    http://www.ti.com/lit/an/slva450a/slva450a.pdf

    If you would like to send me your circuit, please send to michaeldesando@ti.com

    Let me know if you need any additional support. Thanks!

    -Michael