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UCD90160: Desequencing in Auto Mode

pallavi s
Prodigy 130 points
Part Number: UCD90160

Hi,

My design has both sequencing and desequencing requirements.

However in Auto Mode I am not able to see results as per the  desequencing requriements entered.

The design does not use control pin.

In operation mode the desequencing requirements are accepted by the too (shown in the graph ) however the device comes up with all voltages off.

Regards

Pallavi

  • 0
    TI__Guru 58070 points

    HI Pallavi

    There are three MODEs to control power sequence. a proper ON_OFF_CONFIG must be set for each rail to choose one of the mode.

    1. AUTO MODE: under this mode, UCD does not require any external signal or commands, it sequences on all rails automoatically based on the dependencies and timing requirements after device is out of reset.  UCD does not sequence off any rails unless there are faults present any rails and the fault responses are set to shutdown. Bascially there is no purposely sequence off under AUTO Mode.

    2. Control PIN MODE: under this mode, the power sequence on and off are triggered by the CONTROL PIN signal, when the CONTROL PIN is asserted, UCD sequences on all rails based on the dependenceis and timing requirements.  When the CONTROL PIN is  de-asserted, UCD sequences off  all rails based on the dependenceis and timing requirements.

    3. OPERATON MODE: under this mode, there are two options: Purely PMBus Bus Command or using GPIs as PIN SELECTED RAIL STATE

       A. Purely PMBUS Bus command via OPERATION COMMAND: The power sequence on and off are triggered by the exclusive PMBus OPERATION COMMAND. When OPERATION command is set to ON, UCD sequence on all rails based on the dependenceis and timing requirements.  When the OPERATION command is set to off, UCD sequences off  all rails based on the dependenceis and timing requirements.

       B. up to 3 GPI can be used to generate 8 state to control the power sequence on and off without any PMBus Command. Please refer the UCD90XXX PMBus command reference Guide for more details information about this feature.

    Hope this help to understand how UCD works on sequence on and off.

    Once again, please make sure that ON_OFF_CONFIG is set with proper mode.

    Regards

    Yihe