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UDC90120 System Reset, GPI

Kjell Andersen
Prodigy 60 points
Other Parts Discussed in Thread: UCD90120, UCD90124, UCD90910, UCD90160, UCD9090, UCD90120A

In the System Reset tab is is stated that System Reset can be based on time, power-good state of selected rails, the state of GPI pins, or a combination of these things. Does anyone know how to configure the System Reset signal to be dependent on a GPI pin?

  • 0
    TI__Mastermind 42795 points

    UCD90120/UCD90124 can be set up in an indirect way;

    1) Add a GPI pin (Configure tmain tab, Pin Assignment subtab). 2) For the rail of interest, add the selected GPI pin as a GPI Seq On Dependency for that rail. 3) in the System Reset subtab, enable system reset, select the reset pin, check the de-assert .. condition, and check the Rail #. So, the reset pin is dependent on rail # being good and rail # depends on assertion of the GPI.

    UCD90910 (released) and "soon to be released" devices (look at UCD90160 on the TI web site) have direct GPI -> Sys Reset capability. You can download the Fusion GUI and experiment in an offline mode (no devices attached). Launch Fusion and select Offline Mode. Then choose Create New Design/Project, Next, UCD90xxx Sequencers, Next, then choose the appropriate device and the GUI functionality will update according to the features supported within the selected device.

    http://focus.ti.com/docs/toolsw/folders/print/fusion_digital_power_designer.html

  • 0 in reply to Eric Wright
    Prodigy 60 points

    Thank you for your reply and your help. I would prefer the direct GPI to Sys Reset capability which is really what we need.

  • 0 in reply to Kjell Andersen
    Prodigy 60 points

    To simplify my function having system reset dependent of a GPI pin, I have temporarily selected a GPI as a Seq On Dependency for rail as you suggested earlier. When I turn power on I'm monitoring the enable signal for the rail and it works fine (dependent of the GPI pin), but when my card is powered up I'm not able to turn the enable off again by inverting the GPI pin. Please let me know how to fix this.

  • 0 in reply to Kjell Andersen
    TI__Mastermind 42795 points

    There is a difference between how a GPI is evaluated for sequence on vs. system reset funtion. For GPI as sequence on dependency for a rail the GPI state is evaluated for sequence on but after that is no longer evaluated. For system reset function, you can evaluate multiple rail power good or GPI's. You can also use the "GPI tracking" function which might work better for your situation (for UCD90120A, UCD90160, UCD9090).

    Visio-UCD90xxx_GPI_Tracking.pdf