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DM8148 booting from NAND/SD at -5℃

Yu Zhou
Prodigy 20 points

Hi，

We have designed a board with DM8148. It can boot from NAND/SD and start Linux kernel. When the system is booting, the uart console outputs booting information. Everything is working perfect at room temperature.

When we were doing the temperature test from -5℃ to 40℃, we found DM8148 boot up well above 0℃, but failed at -5℃.

We did many experiments, finally we were lucky to find that the key block is 3.3V power rail.

At -5℃, when 3.3V power rail voltage is below 3.30V (for example 3.28V), DM8148 boots from NAND/SD successfully everytime. Otherwise it fails sometimes.

When DM8148 fails at booting from NAND/SD, there is no booting information from uart console. But when we changed the booting mode to booting from UART, the console outputs "cccccccc" about 50s after power up.     

Q1. From datasheet, the requirement for 3.3V power rail is 3.14V~3.46V. Do you have any idea why DM8148 is so sensitive to 3.3V voltage at -5℃? 

(We have tried commercial and industrial class DM8148, but with the same result.)

Q2. What' s the difference between booting from NAND/SD and from UART. Why DM8148 can not boot from NAND/SD but can boot from UART after 50s time delay? 

Thanks,

Yu

  • 0
    TI__Guru**** 170625 points

    Hi Zhou,

    Only the industrial and extended DM8148 device should be able to work in -5℃, not commercial.

    Make sure the surrounding components of the DM814x device are also industrial, components like PMIC, power supply, reset management, oscillator(s), bulk and high-speed capacitors. Make sure you have stable and valid signals on the system boot pins. Make sure the correct power up sequencing is met.

    Yu Zhou said:
    When DM8148 fails at booting from NAND/SD, there is no booting information from uart console. But when we changed the booting mode to booting from UART, the console outputs "cccccccc" about 50s after power up.  

    OK, you have "cccccc" but make sure you are really able to boot from UART (load u-boot, kernel), not just seeing the "cccccc".

    BR
    Pavel

  • 0 in reply to Pavel Botev
    TI__Guru**** 170625 points
    See also if the below doc will help:
    www.ti.com/.../spra953b.pdf
  • 0 in reply to Pavel Botev
    Prodigy 20 points
    Hi Pavel，

    Thanks for your quick reply.

    We are now testing the industrial DM8148.
    We have checked the surrounding components like power supply, reset management, oscillator and the power up sequence is designde as specified in datasheet.
    It is strange that when the 3.3V voltage is modified to 3.28V, the DM8148 works again.
    Do you have any idea about it ?