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UCD90320: UCD90320 OVP query

Dilip Namdeo Mohol
Intellectual 1540 points
Part Number: UCD90320

Hi,

One of TI customer  is  using the UCD in their design. They are facing an issue.  12V is the input to one of  card to derive all the point of load Voltages. UCD is used to provide the Power Sequencing .

During the working condition, whenever there is a dip in 12V,and reappears after some time, They need to make UCD gracefully shut down and when 12V is stable, start the resequencing.

Basically retry more than 1 time. Is it possible to do thr’ GUI . Please let me know how it can be done ..

 

 TI Document_Final.docx

  • 0
    TI__Guru 60800 points

    Hi

    The resequencing only works if all rails are below POWER_GOOD_OFF_THRESHOLD.

    If any rail rise back to the normal voltage before any other rail reaches below POWER_GOOD_OFF threshold, UCD won't resequencing.

    Please see below highlighted rail which is not off.

    Regards

    Yihe

  • 0 in reply to yihe
    Prodigy 60 points

    Hi,

    If you can see the code that we attached in UI, all the voltages will shutdown once there is a UV fault on the rail16 i.e 12V.

    but here the rail state is sequence off but Ideally it should shutdown, as per code.

    What can be done, to overcome this issue.

    Regards,

    Durgarao

    9542553882

    Senior Engineer

    Tejas Networks.

  • 0 in reply to Durgarao Gundu
    TI__Guru 60800 points

    Hi

    The sequencer off means that the turn off dependency was not met. 

    You have to check which rails are turn off dependencies of rail 7

    Does your 12V come back too quick before rail 7 off?

    Regards

    Yihe 

  • 0 in reply to yihe
    Prodigy 60 points

    Hi,

    We have given fault shutdown Slaves of all the rails on VCC12.

    Are these slaves shut down immediately or they follow the turnoff delay sequencing?

    12V comeback or glitch in the voltage is around 50ms.

    Regards,

    Durgarao

  • 0 in reply to Durgarao Gundu
    TI__Guru 60800 points

    Hi

    Only the VCC12(the faulted rail) has the option to do either immediately or delay. but the slave rails of VCC12 can not be shutdown immediately and they always follow the turn off delay.

    Regards

    Yihe

  • 0 in reply to yihe
    Prodigy 60 points

    Thank tou,

    1. Observed when there is interruption in source power supply for 150-180ms, Vcc12 is observing UV fault. Then all the slave voltages are shut down and the resequencing was not happening, all voltages are zero.

    At that moment input voltage to UCD is around 2.8V.

    what can be done here.

    2. In uv fault condition, opted resequencing, Shutdown immediately and donot restart.

    Here in UI contineous restart is disabled.

    We want, if there is an uv fault on BCC12, the resequencing of slave voltages rails has to happen. so, which functions has to be considered?

    Regards,

    Durga Rao

  • 0 in reply to Durgarao Gundu
    TI__Guru 60800 points

    Hi

    1. VCC of UCD below 2.8 would make UCD stop function. Please avoid this

    2. as explained in the previous reply, you have to ensure all rails are off before turn on 12V

    Regards

    Yihe 

  • 0 in reply to yihe
    Prodigy 60 points

    Hi, 

    During the first condition, the device is going into hung state, and have to give power cycle to it. Is there a way to bring the device out of that state, if it enters that state?

    Regards,

    Durga Rao

  • 0 in reply to Durgarao Gundu
    TI__Guru 60800 points

    Hi

    You have to ensure that VCC is above the brownout voltage anytime.

    Regards

    Yihe 

  • 0 in reply to yihe
    Prodigy 60 points

    Hi Yihe,

    Does the UCD have any brownout voltage protection?

    The UCD is getting into hung state, and unable to bring it out of it, even after the UCD voltage rail is proper.

    Do we have an provision for UCD to get reset if it enters this state?

    Regards,

    Durgarao

  • 0 in reply to Durgarao Gundu
    TI__Guru 60800 points

    Hi 

    You have to ensure that the VDD drops below POR before bring the voltage back.

    Regards

    Yihe