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UCC39002: LS and EAO signal behavior of single unit mode

Eric Lai
Expert 4940 points
Part Number: UCC39002

Hi Expert,

The customer run the UCC39002 on the redundant PSU.And 8 units is paralleled in the system.

We would like to know the EAO voltage level

Condition 1) The system only has only one PSU installed.

We see the EAO will increase with increased output load. Is it right?

According to the DS,the error between CSO and LS should be by passed. Is the right behavior of EAO should be zero voltage ?

Condition 2) Then more unit installed. But the AC not provided for them. Only more LS signal be paralleled.

We see the EAO voltage will increase with more LS signal parallel. Is it right?

Since now only the original PSU is working, why the EAO is varied. Then has higher output voltage.

Pls advice. 

Best regards,

Eric Lai

 

Field Application Engineer

Texas Instruments Taiwan Limited

O: +886-2-2175-2582

M: +886-909-262-582

E-Mail:Eric.Lai @ti.com

  • 0
    TI__Genius 9790 points
    Eric,
    I've contacted the appropriate product group. You should hear from them soon.

    Yunsheng
  • 0 in reply to Yunsheng Qu
    TI__Mastermind 34465 points
    Hello Eric,
    At startup the adjust amplifier is forced to sink maximum current through the adjust resistor.
    It does this to quickly begin load sharing for each module.
    It should change to normal operation when the measured current exceeds 80% of the average module current. Since you don't have input power connected to these other modules this state can never be reached. That is why the EAO signal remains high.
    You don't have this issue with a single module and the EAO signal varies directly with the load current requirement.
    Regards
    John Griffin
  • 0 in reply to John Griffin1
    TI__Expert 4940 points
    Hi John,
    Since the customer had adopted the UCC39002 on their board. A document will needed for customer best understanding. Pls tell us where to have the info you addressed.
    Thanks.
    Best regards,

    Eric Lai



    Field Application Engineer

    Texas Instruments Taiwan Limited

    O: +886-2-2175-2582

    M: +886-909-262-582

    E-Mail:Eric.Lai @ti.com
  • 0 in reply to Eric Lai
    TI__Mastermind 34465 points

    Eric,

    It in the data sheet.

    7.3.8 Start-Up and Adjust Logic

     

    Regards

    John

  • 0 in reply to John Griffin1
    TI__Expert 4940 points
    Hi John,

    According to the 7.3.8.During start-up,the load share driver amplifier is disabled by the disconnect switch.
    But why we can see the LS voltage at single unit mode.And its EAO voltage will increased (not max EAO) accompany the LS paralleled.
    Pls advice the LS voltage during start up.

    Thanks.
    Eric