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AM5728: Disabling the AVS

Nomo
Guru 16800 points
Part Number: AM5728
Other Parts Discussed in Thread: TPS659037, TPS65916

Hello,

Can I disable the AVS function?
The AVS function cannot be turned off?

Best Regards,

Nomoto

  • 0
    TI__Guru**** 161600 points
    Hi Nomoto,

    Try disabling CONFIG_REGULATOR_TI_ABB in arch/arm/configs/tisdk_am57xx-evm_defconfig:
    CONFIG_REGULATOR_TI_ABB=n
    This should disable the building of avs class 0 driver (drivers/regulator/ti-abb-regulator.c).

    Best Regards,
    Yordan
  • 0 in reply to Yordan Kovachev
    Guru 16800 points

    Hello Yordan-san,

    Thank you for your reply.
    I have an additional quesion.
    Which voltage domain's AVS is disabled by the configuration?

    AVS work for VD_CORE, VD_MPU and Others.
    I want to know whether all voltage domain's AVS are disabled by the configuration.

    Best Regards,

    Nomo

  • 0 in reply to Nomo
    TI__Guru*** 125430 points

    Please see Table 5-6 of the data manual. AVS is *required* for all rails except rtc.

    Why are you trying to disable AVS? Without AVS you're going to see a much larger variation in current consumption in heat. You may very well encounter thermal issues as a result, and lifetime will be shortened. Furthermore, all of our characterization is done with Smart Reflex enabled, so we cannot guarantee timings or lifetime if you disable AVS. Can you explain why you're thinking about this?

  • 0 in reply to Brad Griffis
    Guru 16800 points

    Hello Brad-san,

    Thank you for your reply.

    The reason why my customer tries to disable AVS is that my customer is considering the possibility not to use PMIC.
    My customer is considering the balance of the cost and the area.
    If PMIC is not used, the voltage of each power rail is fixed and AVS is not needed.
    So, my customer wants to know how to disable the AVS function.

    Best Regards,

    Nomo

  • 0 in reply to Nomo
    TI__Mastermind 26215 points
    Nomo,
    For AM572x it is a requirement to use the PMIC we are specifying in the data manual.
  • 0 in reply to Nomo
    TI__Guru*** 125430 points

    Nomo-san,

    If you wish to comply with our data manual requirements, the TPS659037 is specifically required.  Please refer to Section 8.1:

    TPS659037 is the Power Management IC (PMIC) that should be used for the Device designs. TI requires
    use of this PMIC for the following reasons:
    • TI has validated its use with the Device
    • Board level margins including transient response and output accuracy are analyzed and optimized for
    the entire system
    • Support for power sequencing requirements (refer to Section 5.9 Power Supply Sequences)
    • Support for Adaptive Voltage Scaling (AVS) Class 0 requirements, including TI provided software

    If the cost of AM572x + TPS659037 is too much, perhaps they should consider AM571x + TPS65916.  These devices are tremendously complex, as evidenced by the nearly 8000 page TRM.  When you start to deviate on these fundamental building blocks of the device, you start to have a cascade of issues (current, thermal, stability, etc.).  Please believe me when I tell you that whatever BOM savings you might obtain by cost reducing the PMIC would be lost to engineering cost.

    Best regards,
    Brad

  • 0 in reply to Rogerio Almeida
    TI__Mastermind 26215 points

    Just to be more specific, please check section below in the data manual

  • 0
    Guru 16800 points

    Hello all,

    Thank you for your comment.
    I can understand these devices are tremendously complex and there is large difficulty not to use PMIC.
    I will tell my customers those risks and difficulties.

    Best Regards,

    Nomoto