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TMS320C6670 power-down sequence

Nick Carter
Intellectual 830 points

Hi,all

I'm using 6670 in my design. By looking up the document of 6670, I noticed that power-up sequence is very important to 6670 and the power-down sequence is the exact reverse of the power-up sequence. But how do I control the sequence of power-down?

We usually cut the power of the whole board when we don't use it. Do I have to program to control the sequence of power-down? Or there are some other ways.

Please help!

Thank you

Nick

  • 0
    TI__Mastermind 42545 points

    Hi Nick,

    The idea of the reverse power down is to protect the device similar to the power up sequencing.  We recognize that a in a total power down of the system it's difficult to provide any sequencing but in that case none of the power rails will be present for a significantly longer time.  The real intent of the power down sequencing is to provide guidance in two cases. 

    The first is a controlled power down of the DSPs while the rest of the system remains active.  In this scenario the power supplies should be disabled in a controlled sequence to ensure that the part is not stressed.  Note that the reverse sequence is stricter then absolutely necessary.  In actuality  the power down sequence must be the reverse of an acceptable power up sequence.  Since the Keystone devices support both 1.8V-AVS-1V-1.5V and AVS-1V-1.8V-1.5V sequencing you may be powering down in a different sequence then your power up and still meet the requirement.

    The second is a power down due to the failure of a power supply.  In this case you can't ensure that an proper power down sequence is followed since any of the power rails may have failed but it's important to include some power monitoring that will shut down the rest of the rails in that scenario.  You don't want to continue to partially power a device if a power rail has failed to avoid damage.

  • 0 in reply to Bill Taboada
    TI__Intellectual 2430 points

    Hello,

    May I confirm, I didn't understand the sentence below.

    "Since the Keystone devices support both 1.8V-AVS-1V-1.5V and AVS-1V-1.8V-1.5V sequencing you may be powering down in a different sequence then your power up and still meet the requirement"

    Does this mean power-down sequence is Ok with the reverse way of two power-up sequences?

    I mean, is the same sequence Ok for both power up and down, for example, powering up and down in 1.8V-AVS-1V-1.5V?

    Regards,

    N.Shinozaki

  • 0 in reply to Nori Shinozaki
    TI__Mastermind 42545 points

    Hi Nori,

    The KeyStone I devices support two different power sequences, 1.8V-AVS-1V-1.5V and AVS-1V-1.8V-1.5V. The reverse of either sequence may be used for as a power-down sequence regardless of which was used for the power-up sequence.

    Regards, Bill

  • 0 in reply to Bill Taboada
    TI__Intellectual 2430 points

    Hello Bill,

    Thank you, sorry but let me I confirm again.

    I interpret your answer as follows,

    When power-up in 1.8V-AVS-1V-1.5V, the power-down may be 1.5V-1V-AVS-1.8V or 1.5V-1.8V-1V-AVS(the reverse of AVS-1V-1.8V-1.5V power-up)

    When power-up in  AVS-1V-1.8V-1.5V, the power-down may be 1.5V-1.8V-1V-AVS or 1.5V-1V-AVS-1.8V(the reverse of 1.8V-AVS-1V-1.5V power-up)

    Is this correct?

    Regards,

    N.Shinozaki