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Power down sequence in WinCE 6.0 r3, RTC only mode, Omap L138

Kevin the almighty
Intellectual 780 points
Other Parts Discussed in Thread: TPS65070, OMAP-L138

So our RTC isn't working, and I suspect that its because on our board someone tied the CVDD and RTC_CVDD which connects to DEFDCDC3 on a TPS65070. Wouldn't this mean in order for our RTC to  save the time and have it persist after powering down, we'd only be able to go into a sleep mode? or can the DEFDCDC3 stay on when windows shuts down fully.

I just want to find the power down sequence to see what is left on, My boss is telling me that the RTC always has power and I'm looking at our schematic, thinking, if it always has power, it can never fully be turned off since the core still has power.

  • 0
    TI__Intellectual 1640 points

    Kevin,

    An excerpt from the omap-l138 reference guide section 10.8:

    " ... To put the device in RTC-only mode, there is no software control sequence. You can put

    the device in the RTC-only mode by removing the power supply from all core and I/O logic,

    except for the RTC core logic supply (RTC_CVDD) ..."

     

    Also I don't see any TPS65070 on LogicPD's OMAP-L138 EVM.  Is yours a custom design board?  If not, could you give more details on the version of the board?

    WM


  • 0 in reply to WMK
    Intellectual 780 points

    it is a custom board, though someone had to point out that we had a second RTC so the internal one didn't persist, It just had to be synced with the external one so win CE had the right date.