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Single Ended to Differential Input Stage for TPA3250

aggil liang
Expert 2660 points
Other Parts Discussed in Thread: NE5532, TPA3250

dears

     When TPA3250 is in BTL mode，Can supply dual power ±12V(positive and negative) for the Vcc of input op-amp NE5532  to inprove THD+N? How setup referance volatge of op-amp's noninverting input ? could give the referance schematic

   Another, if it use the dual power supply for op-amp, whether it need to use the Star Ground Configuration such as below ?

    

    

  • 0
    TI__Guru*** 140146 points
    Aggil,

    Your image didn't work, please try again.

    The TPA3250 suggest a AC coupled input so it won't case about the NE5532 supply or the DC component.
    The non inverting input can be connected to (clean) ground via a small series resistance.

    How much gain is needed?
  • 0
    TI__Genius 9175 points
    Hello,

    +/- 12V rails for the NE5532 can be used for better front end performance with some slight modification to the EVM. Note a DC blacking capacitor is still required since the input of the TPA3250 has a common mode voltage.

    The schematic for the EVM can be found here: www.ti.com/.../slvuam9.pdf
    Resistors R37 and R38 provide common mode voltage of 6V "VMID" for the op-amps when running with a single 12V supply.

    The star ground topology is recommended for designs coping the EVM onboard SE to Diff converter. Since it is a single ended system, it is subject to noise injection from the ground plane. The EVM op-amp stage was designed this way to support all input and output configurations of the TPA32xx amplifiers. Dual power supply may help with this.

    Best Regards,
    Matt