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OMAP-L137Real Time Clock

Richard Bullock
Prodigy 60 points

Hi,

Could someone please tell me if it's safe to leave RTC_CVDD unconnected if I'm not using the real time clock?

 

Thanks.

Richard.

  • 0
    TI__Mastermind 37340 points

    when the RTC is not used...

    RTC_XI can actually be tied high or low (funtionally doesn't matter since the RTC would be disabled) but we suspect RTC tied low might be slightly better from a power standpoint.

    RTC_XO can be left open

    RTC_CVDD must be connected to a 1.2V source (RVDD would be the easiest)

    RTC_VSS can be connected to board ground

  • 0 in reply to Juan Gonzales
    Prodigy 60 points

    Many thanks, Juan!

    Richard

  • 0 in reply to Richard Bullock
    Intellectual 805 points

    Hi,

    Datasheet page 57 note 3 states
    "(3) Oscillator (OSC_VSS, RTC_VSS) ground must be kept separate from other grounds and
    connected directly to the crystal load capacitor ground.
    These pins are shorted to VSS on the device itself and should not be connected to VSS on the circuit board."

    Does this apply only when RTC is used.

    Thankyou.

  • 0 in reply to Chikku
    TI__Mastermind 37340 points

    The next revision of the data-sheet should say

    When an external crystal is used oscillator (OSC_VSS, RTC_VSS) ground must be kept separate from other grounds and connected
    directly to the crystal load capacitor ground. These pins are shorted to VSS on the device itself and should not be connected to VSS on
    the circuit board. If a crystal is not used and the clock input is driven directly, then the oscillator VSS may be connected to board ground.

    so when RTC is not used; these seignal should be connected to board ground.