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Original question:

[FAQ] AM625 / AM623 / AM620-Q1 / AM625-Q1 / AM625SIP: Custom board hardware design – Queries regarding VPP eFuse programming...

Clarification needed for VPP termination

Koichiro Tashiro
Mastermind 22945 points


Hi,

I got a question from my customer for VPP termination explained in below E2E FAQ#10.

https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1220816/faq-am625-am623-am625-q1-am620-q1-custom-board-hardware-design-queries-regarding-vpp-efuse-programming-power-supply-selection-and-application

It says:
"Provide a provision to add a discharge resistor. This resistor can be used to terminate the VPP when GP devices are used. The pull-down value needs to be to select such that it doesn't allow any leakage path through the LDO to source a potential greater than 0V when disabled.

Provide provision to populate a very low loop inductance bulk decoupling capacitor(s) located near the VPP pin when VPP is used for the HD-FS devices."

Q1) Both a discharge resistor and a bulk capacitor are needed. What is recommended values for them?
Do you have reference schematics or circuit diagram?

Q2) I guess "HD-FS devices" is typo and "HS-FS devices" is correct, right?

Q3) The No.10 question is "How should I terminate the VPP supply pin for HS-FS device used as a GP device?".
But above answer consists of the case with GP devices are used(1st line) and another case with HS-FS devices are used(2nd line).
Why? Please clarify each usecase.

Thanks and reagrds,
Koichiro Tashiro 

  • +1
    TI__Guru**** 195119 points

    Hello Koichiro Tashiro 

    Thank you for the query. Please refer below answers.

    Koichiro Tashiro said:
    Q2) I guess "HD-FS devices" is typo and "HS-FS devices" is correct, right?

    Thank you for the suggestion. this is updated.

    Koichiro Tashiro said:
    Q3) The No.10 question is "How should I terminate the VPP supply pin for HS-FS device used as a GP device?".
    But above answer consists of the case with GP devices are used(1st line) and another case with HS-FS devices are used(2nd line).
    Why? Please clarify each usecase.

    Thank you for the note. I updated Q.10 to add different use cases.

    Koichiro Tashiro said:
    Q1) Both a discharge resistor and a bulk capacitor are needed. What is recommended values for them?
    Do you have reference schematics or circuit diagram?

    The Caps can be DNI. I updated the Q10 with values.

    Let me know if you have additional queries.

    Regards,

    Sreenivasa