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AM5716: IDK schematic clamp circuits

matusan
Guru 10235 points
Part Number: AM5716
Other Parts Discussed in Thread: TMDXIDK5718, , TPS65916

Hello, TI Experts,

Our customer sent us a question about "the Clamp circuits" of TMDXIDK5718 Schematic as below.

http://www.ti.com/lit/df/sprr242/sprr242.pdf

 

They are designing the prototype board by using AM5716.

Now they are considering to use TPS65916(PMIC) and whether it is possible to remove "the Clamp circuits".

And they also found TPS65916 related AM570x reference design schematics as below;

http://www.ti.com/lit/df/tidrts1/tidrts1.pdf

 

Question:

Can TPS65916 be used to AM5716 without "the Clamp circuits" such as AM570x reference design?

 

We would appreciate if you tell us any comment/notice including how to remove "the Clamp circuits" on system design with AM5716.

 

Best regards,

  • 0
    TI__Guru**** 393215 points
    Hi,

    This question has been asked multiple times here. Please see:
    e2e.ti.com/.../521113
    e2e.ti.com/.../630093
    e2e.ti.com/.../470456

    Note: You can use the search box on top of the forum page to check through previous threads.
  • 0 in reply to Biser Gatchev-XID
    Guru 10235 points
    Hi,

    Thank you for your prompt reply.
    I really appreciate your help.

    We read those E2E-threads which you showed.

    e2e.ti.com/.../470456
    Are these circuit still necessary? -> No answer&Locked.

    e2e.ti.com/.../521113
    there is no need for the clamp circuits? -> No answer&Locked.

    e2e.ti.com/.../630093
    please follow the AM571x reference design.
    Also see Appendix A.10 in the AM571x IDK User Guide

    Those threads seems not to have clear answer to decide that
    TPS65916 can be used to AM5716 without "the Clamp circuits"
    for our customer's board design.

    From those information, we can find the clue from "630093" thread.
    Thank you!
    - "see Appendix A.10 in the AM571x IDK User Guide like below"
    - The companion PMIC, TPS6590377, was enhanced to provide a
    shortened shut-down sequence that enforces the DM requirements
    in a time period (~1ms) that the PMIC input can hold up the supplies.
    The PMIC also has supply discharge resistors to pull down the supplies
    quickly when they are turning off.
    These 2 capabilities in the companion PMIC make the clamp circuits superfluous.

    So, again, they just want to know the answer of the Question below to designd the prototype board.
    Question:
    - Can TPS65916 be used to AM5716 without "the Clamp circuits" such as AM570x reference design?

    We would appreciate if you consider to answer the Question.

    Best regards,
    --
  • 0 in reply to matusan
    TI__Genius 13567 points

    A clamp circuit is needed for this reason: it maintains power to the SoC's VDDS18V rail so that any of the SoC's VDDSHVx (3.3V) supplies don't have a voltage potential greater than 1.55V above the VDDS18V.

    For more details, see the last figure in the datasheet Section 5.9 covering Power Supply Sequences. The AM571x EVM user guide also has an appendix section A10 discussing the clamp.

  • 0 in reply to Ahmad_Rashed
    Guru 10235 points

    Hello,

     

    Thank you very much for your kindness.

    I really appreciate your help.

     

    The answer seems to be "A clamp circuit is needed, if use TPS65916." from your comment.

    But our customer didn't find "any clamp circuit" in the AM570x reference design schematics with TPS65916 as below.

    http://www.ti.com/lit/df/tidrts1/tidrts1.pdf

     

    Our customer expect to refer the schematics of tidrts1.pdf for designing the next board design with AM5716 & TPS65916.

    We would appreciate if you tell us more detail explanation of why "clamp circuit" can be removed in the schematics of tidrts1.pdf.

     

    Best regards,

  • 0 in reply to matusan
    TI__Genius 13567 points
    It is just a reference design. To place the circuit is to be safe and not worry about it.
  • 0 in reply to Ahmad_Rashed
    Guru 10235 points

    Hi,

     

    Thank you for your prompt reply.

    I will send the answer to the customer.

     

    Best regards,