• State Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 29 subscribers
  • Views 263 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

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.

TPA3251: PWM mode and suitable LPF configulation

Mochi
Genius 3865 points
Part Number: TPA3251
Other Parts Discussed in Thread: TPA3255, TPA3245

Hello,

Our customer try to design LPF of TPA3251 seeing Apps note slaa701a "Table 1. Class-D Filter Types and Their SE Equivalent Circuits" on page 8.

There are LPF configurations as Type-1 for AD mode, Type-2 for BD mode and Hybrid.  We know BD mode cannot accept Cbtl which placesd across +output and -output node.

In the case of TPA3251, no description of PWM mode on the datasheet.

We would like to confirm PWM mode of TPA3251 and suitable LPF type.

Our expectation is that its AD mode and all of LPF type can be used. Is it correct?

 

Regards,

Mochizuki

  • 0
    TI__Mastermind 31580 points

    Hi  Mochizuki

        Our newer device all use BD modulation, it will reduce the high frequency components flows into the speaker, better for the EMI and efficiency. TPA3251 only use BD.

        Even in AD modulation, we still recommend to use the capacitor connected to GND. Because in realities, AD is not perfect differential. 

  • 0 in reply to Shadow He
    Genius 3865 points

    Hello,

    Thank you for the reply.

     We understood even AD mode D-amp, placed bypass cap between GND is better for lowering EMI.

    The other hand, attached waveform is TPA3251 PWM output waveform, we believe it is AD mode.

    In our knowledge, TPA3251 is the first generation of TPA32xx family device, TPA3245 and TPA3255 are younger generation device but it is employed AD mode modulator as described it on the datasheet.

    So, would you please check it out again about TPA3251 is using AD mode too.  And AD mode D-amp device can accept all of Type-1, Type-2 and Hybrid LPF configuration.

     

    Regards,

    Mochizuki

  • +1 in reply to Mochi
    TI__Mastermind 31580 points

    Hi  Mochizuki

     

    Mochi said:

    So, would you please check it out again about TPA3251 is using AD mode too.  And AD mode D-amp device can accept all of Type-1, Type-2 and Hybrid LPF configuration.

     

     

      You are correct, thank you.