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AM5728: Processor selection having good thermal stability

Krishna Vashistha
Intellectual 770 points
Part Number: AM5728

Hello,

To design a product in the thermal imaging world.

the selection of appropriate processors we need your help to move ahead.

We have gone through the link below:-

https://www.ti.com/solution/thermal-imaging-camera?variantid=35029&subsystemid=23906

The information seems fair enough while selection of core components.

As we already designed a prototype with AM572x processors. Our all modules are working fine.

But we are getting failure result in thermal management scope.

The assembled electronics in mechanical housing reaches up to 90 C (processor on die temp sensor)

at ambient of 25 C only.

Although the complete mechanical design is being considered as a heat sink for natural convection.

All documents i.e. ARM & DSP thermal consideration, power estimation tool has been read out.

We did best as per our knowledge and the resources provided by TI.

Please assist us either processor selection having low power feature or optimized scheme for good

thermal management for am572x devices.

Regards

Krishna Vashistha

  • 0
    TI__Guru 54552 points

    Krishna,

    -1-

    Have you performed thermal simulations of your system?  We would suggest using a tool like Flotherm to model the PCB + SoC + other components + 3D model of chassis to get an idea of whether the heat sink/chassis is sufficient to remove the heat from the device.

    AM572x 23 mm Thermal Models (Rev. A)

    -2-

    Is the heat sink touching the SoC lid firmly with a thermal interface material?

    -3- 

    How may systems have you tested?  Is there a range of final temperatures? Can you summarize?

    -4-

    For the worst and best systems ... can you provide a log file showing the 5 on-die temp sensor readout (Tj) vs Time?

    -5-

    Have you confirmed the various cores are running at the desired frequencies and voltages?  Are you enabling AVS?

    -6- 

    Can you show pictures of your system/chassis/heatsink?

    -7-

    You might consider running at reduced OPP.  I.e., instead of 1.5 GHz/OPP_HIGH try running the Arm Cores at 1.0 GHz/OPP_NOM.

    Regards,

    Kyle

  • 0 in reply to kcastille
    Intellectual 770 points

    Dear Kcastille,

    Thank you for the response.

    1. Have you performed thermal simulations of your system?  We would suggest using a tool like Flotherm to model the PCB + SoC + other components + 3D model of chassis to get an idea of whether the heat sink/chassis is sufficient to remove the heat from the device.

    -Not performed yet, we will definitely try it.

    2. Is the heat sink touching the SoC lid firmly with a thermal interface material?

    -Right now we are not using any heat sink, checking in open environment.

    3. How may systems have you tested?  Is there a range of final temperatures? Can you summarize?

    4. For the worst and best systems ... can you provide a log file showing the 5 on-die temp sensor readout (Tj) vs Time?

    -please see the log Temp_data.pdf

    5. Have you confirmed the various cores are running at the desired frequencies and voltages?  Are you enabling AVS?

    -We are using cortex A15@ 1Ghz  dual core other remote core has been disabled.

    We assume AVS managed by PMIC.

    6. Can you show pictures of your system/chassis/heatsink?

    Regards

    Krishna Vashistha

  • 0 in reply to Krishna Vashistha
    TI__Guru 54552 points

    Hello Krishna,

    Please confirm that AVS voltage domains are being correctly set in the PMIC.  This is done in software by reading the AVS Class 0 registers and programming the PMIC via I2C.

    Also, a heat sink will likely significantly help.

    Regards,

    Kyle

  • 0 in reply to kcastille
    Intellectual 770 points

    hello kcastille,

    We have tried to interface with PMIC via i2c and able to access AVS register value.

    It is found that  all core domains are set to its default nominal range as per datasheet.

    We also reduces voltage by changing respective domain i.e. SMPS12_FORCE_REGISTER ,SMPS45_FORCE REGISTER but nothing appeared good in thermal behavior.

    One more think which I want to ask, Is it okay to disable the unused LDO supply or the IO

    peripheral power domain?

    Regards

    Krishna Vashistha

  • 0 in reply to Krishna Vashistha
    TI__Guru 54552 points

    Krishna,  After reducing voltage by setting registers in the PMIC ...can you measure the voltage with a multimeter or scope and see that they are modified?

    No you cannot disable the supplies to the SoC.  You can disable PMIC outputs if they are not connected to the SoC.

    You're going to need a heat sink...

    Regards,

    Kyle

  • 0 in reply to kcastille
    Intellectual 770 points

    Hello kcastille,

    Thank you for the response.

    Yes, We have already checked the voltage using multi meter.

    It gets modified according to our desired value.

    Regards

    Krishna Vashistha