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TPA3255: TPA3255 application problem

aggil liang
Expert 2660 points

Part Number: TPA3255

Hi Teams

   when we used TPA3255, we have some questions. 

1.  In the datasheet,  7.1 Absolute Maximum Ratings, the INPUT_X to GND range is  –0.3 to  7 V, but  page 18, 10.2.4.1 Design Requirements, Analog Inputs INPUT_A = ±3.9V (peak, max) INPUT_B = ±3.9V (peak, max), how we understand it ? 

www.ti.com/.../slasea8a.pdf

2. In the TPA3255EVM user's guide,  Part 1, TPA3255EVM is a complete 2-Vrms analog input 2 × 315-W stereo/1 × 600-W mono high-power amplifier ready for evaluation and excellent listening experience.

but in part 1.1, Standard 4-VRMS differential input or single-ended line input. 

 this two describtion have different input voltage, which is right ?

www.ti.com.cn/.../slou441.pdf

3. In the EVM user guide, PVDD cap,  C32/C33/C47/C48. customer is also use the 1206 package, 100V /1uf. but it always happen to broken down ? The input power is steady.  Can you give some suggestion ？

  • 0
    TI__Mastermind 28120 points
    Hi Aggil,

    1. Sorry this is a bit confusing. The TPA3255 input pins can take a maximum of 7V inputs for the full scale input (over 10% THD). Technically you can go a bit further to +/-3.9 V peak, or 2.757Vrms but you are way into clipping with over 20% THD. Depending on how much THD you want on the full scale output of your application, you should tune the input signal max to that amplitude.

    2. The 2 Vrms figure is per pin. So in SE, the 2Vrms for one input is correct, in BTL you look across two pins meaning 4 Vrms differential.

    3. I am not sure what you mean, are you saying the local bulk caps are failing on the board? I have not seen this issue before.

    Justin
  • 0 in reply to Justin Bohr
    Expert 2660 points

    Hi Justin

           I mean below caps in the red highlight area. they are easy to fail. How we select these caps ?

       

  • 0 in reply to aggil liang
    TI__Mastermind 28120 points
    Hi Aggil,

    The image = did not come through.

    If you are talking about the bulk caps, then I am not sure why they are failing. Are they under a heat sink and possibly shorting to it? with the 100V/1uF there should not be any reliability issues. What type of capacitor are they?

    Justin