• State TI Thinks Resolved
  • Locked Locked
  • Replies 6 replies
  • Answers 1 answer
  • Subscribers 32 subscribers
  • Views 911 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TLV320AIC3110: ferrite bead slection

KANJI SHIBATANI
Mastermind 6205 points
Part Number: TLV320AIC3110

 

Hello

My Customer use TLV320AIC3110 for their new product which is active speaker.

 

They are evaluating their board , but class-D amp output indicates

higher THD in case signal is above 5KHz.

We are investigating , but cause unknown.

 ( Headphone output is Okay even 5KHz)

Would you please advise following? I attached their schematic and phenomenon on ppt file.

 

Question 1

On the TLV320AIC3110 d/s *page 64, device has short-circuit protection.

Anyway, what is the typical value for the prptection current ( amps)?  

>*d/s page 64

>The TLV320AIC3110 device has a short-circuit protection feature for the speaker drivers that is always

>enabled to provide protection. If the output is shorted, the output stage shuts down on the overcurrent

>condition.

Question  2

They are using 1.5A ferreite bead and chip capacitor for LC filter.

Their speaker is Fostex 8ohm speaker : attached ppt.

I think their schematic ( 1.5A bead  is no problem, but How do you think?

Ferrite Bead :BLM15EG121SN1  

120ohm at 100MHz rating 1500mA http://docs-asia.electrocomponents.com/webdocs/12ab/0900766b812ab03c.pdf

 

Thank you for your supprt.

With My Best Regards

 

 

TLV320AIC3110_usage.pptx 

  • 0
    Intellectual 640 points
    Hello Kanji,
    It is not clear whether the overcurrent protection is an option for the Class-D amplifier (they say that this option is not available for the "high-current speaker driver"). I hope a TI engineer will help you on that.

    As for the ferrite bead, does your customer use it on the output stage? TLV320AIC3110 uses a filterless Class-D amplifier. Did you try to test this amplifier *without* the LC filter? I adnmit that iIt is good to have an EMI filter placed before the Class-D waveform reaches the speaker cable but I doubt that a shunt capacitor is allowed to exist there. Plus the fact that the ferrite bead you are using is rather small (it will not be damaged but its effect will significantly deteriorate due to the bias current effect). Use a 0603 sized bead or, preferably, a 0805. Larger beads usually suffer a lot less from bias current effect plus they usually exhibit a more flat attenuation band.

    Regards
  • 0
    TI__Mastermind 30210 points

    Shibatani-San,

    My apologies for the delayed response.

    1:  I will need to check with design to confirm,  my guess is that it is 1.5A,  But I will check and get back to you.

    2:  the ferrite bead they are using is the one that we recommend using in this application report.  It should not be a problem. 

    Can you tell me more about their measurements? what is the speaker impedance?   do they have any THD measurements using an AP?  Their schematic looks alright to me at first glance.  can you provide me with a layout?

    -Steve Wilson

  • 0 in reply to Dimitrios Papadopoulos
    Mastermind 6205 points

    Dear Dimitrios-san,

    Thank you for your comment.

    Best Regards

     

  • 0 in reply to Steve-Wilson
    Mastermind 6205 points

     

    Dear Steve-san,

    Thank you for your answer/ application report.

    In regard to 2:,speaker impedance is 8 ohm.

    If I had more detail information from customer, I will infrom you later.

    Best Regards

     

  • 0 in reply to KANJI SHIBATANI
    TI__Mastermind 30210 points
    Shibatani-San,

    Did you have more details from your customer? please let me know if we can be of any assistance.

    best regards,
    -Steve Wilson
  • 0 in reply to Steve-Wilson
    Mastermind 6205 points

    Dear Steve san

    Thank you for your notice.

    I am asking customer further test,but it takes time.

    Please discard this question.

    Thank you for your support.

    With my best regards