• Resolved

TPA3255: Single-ended for TPA3255 without op amp stage

Part Number: TPA3255

Hello, i am thinking if i can connect the inputs of the TPA3255 without the op amp stage ensuring that the single-ended signal are converted into balanced connexion? Is it possible to only connect the single-ended connexion to one input channel (by putting a dc blocking capacitor on the input A pin and connect it directly to the main signal source, and the input B pin to a same value capacitor, (like 10uf) but to the tpa3255 ground), like it is commonly done on the TPA3116 ? If i would like to do this, it's to minimize cost and achieve a better sound quality.

Thanks for your response to come.

  • Hello,
    I think you are asking whether TPA3255 supports single-ended input mode, right?
    Best regards,
    Shawn Zheng
  • In reply to Shawn Zheng:

    Yes, that's it. I would like to know if this chip can support single-ended input mode.
  • In reply to Lulu Lulu:

    Hi Lulu,

    Yes the TPA3255 can support a single ended input into the A side for a BTL mode, but you will not be able to get the full output, as you are only providing half the input amplitude of the differential signal.

  • In reply to Justin Bohr:

    Hello, that's not an problem for me, as i don't plan to connect the amplifier to powerfull speakers. But single ended connexion aside, is it possible to create a first order rc crossover by using a resistor and capacitor before the tpa3255's audio inputs to minimize the value of the capacitor (i assume that the input impedance of the amplifier is already making a rc crossover with the capacitor, but, due to the weak input impedance of the tpa3255 chip, it implies to use a relatively high value capacitor of 10uf, that should be electrolytic for cost and proportions reasons, so by making a rc filter, it allow me to use a smaller capacitor like a film one that is better)? But i think that, if i make a rc capacitor before the tpa3255's input, the input impedance of the chip will compromise the total filter operability as, there isn't directly a resistor in paraller to ground in the tpa3255's internal circuit, but most a voltage divider or something alike... So if i do so, i suppose that there will be some noise/pop issues resulting of that ? I am wrong ? Cordially
  • In reply to Lulu Lulu:

    Hi Lulu,

    Adding a large RC to try and change the response with the DC blocking cap would significantly reduce the input amplitude to the amplifier. I would recommend using at least a 2.2uF capacitor since this will still give a corner frequency of less than 10Hz.