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OMAP3530: Sleep Mode

Charles McCarthy
Intellectual 500 points

Other Parts Discussed in Thread: TPS65920

I posted the question below on another message that had already been "answered" so maybe it got lost in the shuffle...

Hello.  I have a pretty basic question about the OMAP3530 SYS_OFF_MODE / TPS65920 nSLEEP1 interface, I think similar to the original question in this posting trail.  It appears to me that the default OMAP3530 SYS_OFF_MODE state is low (deasserted) and it asserts high when the OMAP wants the TPS65920 to turn off most of the power to the OMAP (i.e., OMAP wants to go to "sleep").  However, the TPS65920 nSLEEP1 signal defaults to active low. That is, when a low signal is asserted onto nSLEEP1 the PMIC turns off several of the supplies to the OMAP processor.  This seems to be in contradiction to the default state of the OMAP SYS_OFF_MODE output.  I know the OMAP SYS_OFF_MODE is programmable, so do this mean the software must configure the SYS_OFF_MODE to active low (i.e., "nSYS_OFF_MODE") for the two devices to communicate correctly?

Please clarify.

Regards,

Charles

  • 0
    TI__Mastermind 41665 points

    I believe you are correct, to enable the SYS_OFF_MODE signal to work with the nSLEEP1 signal you would have to change the polarity on the OMAP3 end in your firmware. It looks like it will still work when powering up initially because nSLEEP1 is ignored until you set P1_SW_EVENTS.LVL_WAKEUP as discussed in SWCU052c, so you would just have to adjust the polarity before enabling LVL_WAKEUP on the TPS65920