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[ LM48100-Q1 ] Malfunctioning Output

Kenichiro
Mastermind 9165 points

[ LM48100-Q1 ] Malfunctioning Output

Hi,

My customer has reported that the malfunctioning output from ESD test.
Before applying the ESD voltage (+/-8kV) to output pins (OUTA and OUTB), the output waveform is normal.

However, after applying the ESD voltage to OUTA and OUTB, the output from OUTA and OUTB turn to be in the same phase (synchronization), and it's no more differential signal. it means no sound.



In this state, once customer send some commands to LM48100-Q1, then LM48100-Q1 goes back to normal mode (playing back tone.) So it's assumed that the device is not damaged.

Can you explain why this happen? and how does ESD voltage affect to operational mode?

Thank you for your support in advance.
Regards,
Ken

  • 0
    TI__Mastermind 20085 points
    Hi Kenichiro

    This behavior is odd, I'm going to research about that and I'll come back to you as soon as possible with more information.

    Best Regards
    Jose Luis Figueroa
    Audio Applications Engineer | A-Team
  • 0 in reply to José Luis
    Mastermind 9165 points
    Hi Jose,

    Thank you for your support! Can I have an update/comment within today?
    Sorry for rushing you, but the customer is really close to production start.

    I have communicated with the customer and shared that only ESD specification of HBM and CDM are specified in the datasheet.
    The Customer also noticed that point and tried some combinations of ESD protection devices, but still cannot be improved.

    What the customer expect from us at this moment is some kind of estimation and/or assumption how the device can go into this mode.

    Thank you for your support in advance.
    Regards,
    Ken
  • 0 in reply to Kenichiro
    TI__Mastermind 20085 points
    Kenichiro

    Unfortunately, we can't guarantee a correct operation if the customer doesn't follow the provided guidelines in the amplifier's datasheet.
    Could you provide me the values of the registers before and after of that this condition happens? and Do you know if Fault pin detects a fault condition after applying the ESD voltage? This information could be useful to determinate a possible cause.

    Best Regards
    Jose Luis Figueroa
    Audio Applications Engineer | LPAA
  • 0 in reply to José Luis
    Mastermind 9165 points
    Hi Jose,

    Yes, that's what customer need to make sure the operation on their board.

    I'm asking them to share the information (register value and some other observations) with us as much as possible. I will share with you once I have it.

    Can you check whether there is an instance that LM48100 make same phase output?

    Thanks,
    Ken
  • 0 in reply to Kenichiro
    TI__Mastermind 20085 points
    Hi Kenichiro

    Sure, I'll continue working on this and I'll come back to you if I find something useful.

    Best Regards
    Jose Luis Figueroa
    Audio Applications Engineer | LPAA
  • 0 in reply to José Luis
    Mastermind 9165 points

    Hi Jose,

     

    Here are the register information and some findings that customer has tried so far.
    Please take a look and give me your feedback.

    ---

    < Register Settings, before failure happen >:

     

    Mode Control Register:                           0x14

    Diagnostic Control Register:                   0x20

    Fault Detection Control Register:           0x47

    Volume Control 1:                                      0x7B

    Volume Control 2:                                      0x80

     

    < Command sending test, after failure happen 1>:

     

    Mode Control Register:         0x00

    Mode Control Register:         0x14

     

    No improvement (same phase)

     

    < Command sending test, after failure happen 2>:

     

    Volume Control 1:                    0x7B

    Mode Control Register:         0x00

    Mode Control Register:         0x14

     

    Improved, resume playback with differential signal

     

    < Performing Continuous Diag.>:

     

    Changing register settings, before applying ESD / failure happen.

     

    Fault Detection Control Register:         0x40

    Diagnostic Control Register:                   0x38

     

    During performing continuous diag., LM48100 does not play sound (as expected).

    Then customer keeps monitoring FAULT signal (low = fault).

     

    Applying ESD, then failure mode confirmed. No FAULT indication (still keep high).

     

    Then sending the following command to disable continuous diag.

    Diagnostic Control Register:                   0x24

    Diagnostic Control Register:                   0x20

     

    No FAULT indication (still keep high), also same phase

     

    Then sending following command.

     

    Volume Control 1:                    0x7B

    Mode Control Register:         0x00

    Mode Control Register:         0x14

     

    Improved, resume playback with differential signal

    ---

    Thank you for your support as always.
    Regards,
    Ken

  • 0 in reply to Kenichiro
    Mastermind 9165 points

    Hi Jose,

    Can I have some feedbacks from your side today?
    Sorry for rushing you...


    Thanks,
    Ken

  • 0 in reply to Kenichiro
    TI__Mastermind 20085 points
    Hi Kenichiro

    I have been researching about this matter. Unfortunately, I haven't been able to find something about this issue.
    You must take into account that it is quite difficult to find this kind of information due to this device is old part and the people who works with these parts isn't longer on ti.
    But I'll continue researching and let you know if I find something about this.

    Best Regards
    Jose Luis Figueroa
    Audio Applications Engineer | LPAA
  • 0 in reply to José Luis
    Mastermind 9165 points

    Hi Jose,

    Thank you for working on this...I see that you have no information...hmm : (

    Thanks,
    Ken