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ABB LDOs Control for AM572x

Michi Yama
Guru 10030 points

Hi,

 I have one question for ABB LDO control for AM572x.

According to TRM 3.8.3.3 ABB LDOs Control,  it is written as the below.

       FBB mode is enabled when the device is a weak process device at the highest OPP.

Now my customer always enables FBB mode regardless OPP mode. Is this no problem? If this is problem, I would like to know the criteria for FBB mode enable/disable.

I appreciate your quick reply.


Best regards,

Michi

  • 0
    TI__Guru**** 393215 points
    I will forward this to the AM57X team.
  • 0 in reply to Biser Gatchev-XID
    Guru 10030 points
    Biser-san,

    Thank you for your support.

    Regarding my question, I checked the AM57xx DM. According to Table 5-7 Note(4), the below comment is written.

    (4) For all OPPs, AVS must be enabled to avoid impact on device reliability, lifetime POH(Power on Hour), and device power.

    I think this is different from TRM comment I wrote before. Which is correct?

    Please advise me.

    Best regards,
    Michi
  • 0
    TI__Guru**** 161600 points

    Hi Michi,

    Sorry for the delayed response.

    "I would like to know the criteria for FBB mode enable/disable."

    The FBB mode is used, when you are working on a weak device & the device is operating on its highest OPP (OPP_HIGH). The bellow figure explains which devices are WEAK (COLD) & which devices are STRONG (HOT):

    As you know when working on highest OPP, there is the risk for entering critical thermal conditions. Therefore the power management has means to try and lower the power consumption according to the use case, i.e. FBB can be applied by lowering VBBNW/body bias voltage/ (VBBNW < VDD) to reduce the threshold voltage and increase performance.  As per my understanding, the rule is to enable FBB, when device is using OPP_HIGH & to use bypass mode the voltage domain enters low power mode. 

    As per your second query:

    "I think this is different from TRM comment I wrote before." 

    I am not sure there is a discrepancy between the documents. 

    Hope this helps. 

    Best Regards, 

    Yordan

  • 0 in reply to Yordan Kovachev
    TI__Mastermind 25050 points

    AVS (Adaptive Voltage Scaling) is a mechanism, intended to minimize power consumption by applying different (clock/voltage) operating points (OPP). Whenever full performance is not  needed, the clock speed can be reduced , and voltage can be lowered (OPP). With AVS this can be done dynamically.

    That is, AVS is independent feature from ABB,  and therefore, TRM/DM statements do not contradict to each other.