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LM3880: About "8.3 Do's and Don'ts"

Tsukui Yusuke
Guru 21930 points
Part Number: LM3880

Hi,

Could you tell me about "Datasheet page 15 8.3 Do's and Don'ts" ?

1.What happens inside the device when VCC and EN are connected, causing undefined operation?
　Please give details of the problem.

2.Customer has connected Vcc to EN.
　Devices that have been found to have no problems will not cause problems again.
　Is this understanding right?
　Customer wants to reject the problematic device during testing.



Customer is unable to modify the schematic.
Could you give me your advice？

Regards,
Yusuke

  • 0
    TI__Guru 62260 points

    Hello

    It has a requirement that the EN shall stay below it ON threshold before VCC reaching 2.7V. Having EN tired direct VCC can not guarantee the requirement.

    So the behaviors of the device is unpredicted since this is out of design requirment. They have to change the design based on what data sheet recommends.

    Regards

    Yihe

  • 0 in reply to yihe
    Guru 21930 points

    Hi Yihe,

    Thank you for your response.
    Its contents were added in Revision K.
    However, no description was given in the change history.

    Customer wants to know the detailed explanatory material that has been added.



    Regards,
    Yusuke

  • 0 in reply to Tsukui Yusuke
    TI__Guru 62260 points

    Hi

    The reasons have been explained. The device's function is undecided If they do not follow what is recommend,

    When did they start the design?

    Regards

    Yihe

  • 0 in reply to yihe
    Guru 21930 points

    Hi Yihe,

    Thank you for your support.
    Customer design is complete.
    A start up failure occurred and they noticed this problem.
    Rev J data sheet at the time of design did not state that "should not be connected to Vcc and EN".

    Customers want to know why "Do's and Don'ts"  was added in the Rev K data sheet.
    And  want to know the internal circuit factors that cause " The device's function is undecided " to occur in LM3880.

    Regards,
    Yusuke

  • 0 in reply to Tsukui Yusuke
    Guru 21930 points

    Hi,

    Thank you for your support as ever.
    I close this thread once because we are talking by internal mail..

    Regards,
    Yusuke