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TAS5731 / No load operation

S.Satoshi
Guru 21685 points

Other Parts Discussed in Thread: TAS5731

Hi Don-san,

Our customer is asking the continuous operation at no load but under OCP threshold. Can you guarantee the long-term reliability at this condition? If you do not recommend to operate at no load continuously, please let us know the reason and acceptable duration of no load operation.


Best Regards,

Sonoki

  • 0
    TI__Mastermind 22965 points

    Hi Satoshi-san,

    No-load condition is not recommended, since the LC-filter response can have significant peaking (i.e. low impedance). Please advise customer not to use this configuration. 

    Do you know what is driving their requirement for no-load operation? 

    -Ravi

  • 0 in reply to Ravi Singh
    Guru 21685 points

    Hi Ravi-san,

    Thank you for your quick response.

    They suppose the case of  the speaker is disconnected at abnormal conditions. 

    I understand that you can not recommend the no load condition for short duration. Do you have some idea of protection for this condition?

    Best Regards,

    Sonoki

  • 0 in reply to S.Satoshi
    TI__Mastermind 22965 points

    Hi Satoshi-san,

    If they can place the device in shut-down mode, on open-load detection, it should be fine.

    -Ravi

  • 0 in reply to Ravi Singh
    Guru 21685 points

    Hi Ravi-san,

    Thank you for your comments. I close this thread but please let me ask again if customer have further question for this discussion.

    Best Regards,

    Sonoki

  • 0 in reply to S.Satoshi
    Guru 21685 points

    Hi Ravi-san,

    We received additional question from our customer.

    Can you accept the no load condition for approximately 100msec after speaker is disconnected? They are pointing that the short duration like this should be accepted because the external open load circuit need some delay to detect open load.

    In this case, they assume that the open load condition will be happened under OCP threshold condition.


    Best Regards,

    Sonoki

  • 0 in reply to S.Satoshi
    TI__Mastermind 22965 points

    Hi Satoshi-san,

    If the auto-retry period (register 0x1A) is set to default (125mS or higher, 100ms condition should be fine.

    -Ravi

  • 0 in reply to Ravi Singh
    Guru 21685 points

    Hi, Ravi-san,

    I may not communicate what I'd like to say, so please let me explain again. I apologize for not providing you with enough information.

    Our customer is simulating that the speaker is disconnected during operation. They think that It may need approximately 100msec to detect the disconnection and disable TAS5731 after disconnection. So they would like to ask if you can accept this short period of disconnection.


    Best Regards,

    Sonoki

  • 0 in reply to S.Satoshi
    TI__Mastermind 22965 points

    Hi Satoshi-san,

    My apologies. I was not very clear in the last post. Please let me elaborate on my earlier comment ..."If the auto-retry period (register 0x1A) is set to default (125mS or higher, 100ms condition should be fine".

    As you know, when the device detects an error-condition (such as Over-Current), device goes into protection mode, and then periodically tries to do a auto-retry to check if error status is still present. The default auto-error recovery time period is 125ms (this is defined by register 0x1A). 

    If they can detect the error-condition in <100ms and shut-down the device, it means that the device only goes through one error cycle (instead of a continuous re-try). 

    As I described earlier, in some cases the device can go in over-current condition in a no-load case (due to LC filter peaking, esp at higher input frequencies). The best case is not to have open-load, but if this is an error condition, detecting and shutting the device in 100-ms should work fine.

    -Ravi

  • 0 in reply to Ravi Singh
    Guru 21685 points

    Hi Ravi-san,

    Thank you for the detailed explanation. We could understand what you commented clearly. I hope we can close the question about no load condition.


    Best Regards,

    Sonoki