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AM3354: Device differences vs AM3358

Koichiro Tashiro
Mastermind 21730 points
Part Number: AM3354

Hi,

My customer is using AM3354BZCZD60.
Due to deliver shortage, the customer is planning to use AM3358BZCZA80 as replacement.

As far as I understood from datasheet, there are a few differences between these two parts.
1) The max CPU frequency (600MHz vs 800MHz)
2) PRU feature enabled or disabled, so dev_feature register values are different, too.
3) Operating temperature range (-40 to 90C vs -40 to 105C)

Question:
The customer wants to use their software running on AM3354BZCZD60 to AM3358BZCZA80.
So frequency is 600MHz and PRU is not used.
In this case, do you have any concerns to replace AM3354BZCZD60 with AM3358BZCZA80?

I thought if dev_feature register is not used in their software, there is no concern.
Correct?

PRU is disabled as default, so no power consumption differences are expected? 

Thanks and regards,
Koichiro Tashiro



  • +1
    TI__Mastermind 24785 points

    Your analysis of the differences is correct. 

    The PRU is disabled by default. 

    Attached below is something I put together as a guide for those looking to substitute AM335x devices. 

    --Paul

    Power

    When substituting a device with a device that contains additional features, you should see not increase in power as these features power up in a reset state and must be activated by software before they will consume power.

    This applies to the 3D GPU and Industrial protocols.

    See Table 8-28. Power Domain State Table  in the TRM for details of Reset States.

    Features  

    The DEV_FEATURE register will be different for different AM335x devices.

    This register can be used to determine which part is installed in a system.  If your system software uses this register to identify the processor, you will need to confirm that the change in value will not impact the operation of you system.

    The DEV_FEATURE value for each device can be found at the bottom of the device comparison table in the AM335x datasheet.

    You can use a device with additional features as a substitute. However, If you need a feature such a GPU, you cannot substitute a device that does not support that feature

    Speed Grade

    You can substitute a faster speed grade in place of a lower grade device.  You cannot substitute a lower speed grade for a faster device unless you are running at, or below the maximum speed of the substituted device.

    The maximum speed of a device can be read from the efuse_sma register, see table 9-59 of the TRM for details.   If your software hard-codes the maximum device frequency then differences in this register will not impact your system.

    However, if you s/w sets the maximum frequency based on this register, then you may encounter issues with the processor running faster than expected.  

     

    Temp Grade

    You should not substitute a device with a lower temp grade device.  This is true, even if you are substituting a faster speed grade at a lower speed.

     

    Package

    The substitute device must be the same package type. You cannot use a ZCZ in a ZCE application, nor can you use a ZCE in a ZCZ application.

     

     

     

  • 0 in reply to PaulM
    TI__Mastermind 21730 points

    Hi Paul,

    Thanks for your quick and detailed answer!

    Thanks and regards,
    Koichiro Tashiro