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TPA3100D2: TPA3100D2 speaker output voltage

satya dutt
Prodigy 250 points
Part Number: TPA3100D2

Can somebody tell me what should be the voltage on the speakers outputs of TPA3100D2 in BTL format, the supply voltage is about 24 volts. None of the speaker outputs is grounded or supplied through a capacitor.

Thanks

Satya

  • 0
    TI__Mastermind 24835 points
    Hi Satya,
    I'm sorry I'm not sure if I understand your question correctly. Do you mean the max voltage on the speaker + and - with 24V PVCC power supply? Generally the max voltage on the speaker is close to PVCC and -PVCC. But it's also limited by the output current and thermal peformance. Make sure the OC and OT fault is not triggered.
    Best regards,
    Shawn Zheng
  • 0 in reply to Shawn Zheng
    Prodigy 250 points

    Thanks, I mean what is the voltage expected on the output? In my experience the four outputs should show 8 or 9 volts on each of the pins. I have an  amplifier whose ic TPA3100D2 appears to be  not working and it shows 9 volts each on two of the outputs and zero on the other two.

    I am trying to determine if the ic is defective or there is a defect in the parts connected to it.

    The speakers have been tested and are OK.

  • 0 in reply to satya dutt
    TI__Mastermind 24835 points
    Hi Satya,
    With 24V PVCC and no input signal, the device is working in idle status. In this case, the device is outputing 50% duty-cycle PWM, so the common voltage on the output pins should be around 12V. If the voltage on the pins are zero voltage, it means that there is no PWM output from the device. Please replace the device to see if it works normally. Or check the components/soldering on the board to see if there is any system application issue.
    Best regards,
    Shawn Zheng
  • 0 in reply to Shawn Zheng
    Prodigy 250 points

    Hello Shawn,

    Thanks for your message. With audio being fed in,there are about 2.4 volts in three of the inputs, while the fourth has 3.4 volts. I can trace the audio in each of these inputs.

    There is no capacitor but a resistor of 103 ohms feeding these inputs.

    The two speaker outputs are showing 9 volts on one side EACH and zero on the other side, with speakers disconnected.

    When I connect the speakers, the smps power supply goes to zero.

    Do not have a circuit diagram otherwise would have sent you.

    With best wishes.

    Satya

  • 0 in reply to satya dutt
    TI__Mastermind 24835 points

    Hi Saya,

    Sounds like the DC block capacitors on the input are NOT used in your application, please add 1uF capacitors on the input.  The Figure24 in the datasheet shows a typical application circuit for TPA3100D2. 

    Best regards,

    Shawn Zheng  

  • 0 in reply to Shawn Zheng
    Prodigy 250 points

    Thanks, let me see if I can do it. This ic runs the tweeters and there is a different ic which runs the woofer, but both are powered from same smps. Even the other ic does not have any

    capacitor to to its input. The other ic and the woofer work, if I do not connect the tweeters to the ic.

    With best wishes.

    Satya

  • 0 in reply to satya dutt
    TI__Mastermind 24835 points
    Hi Satya,
    The input DC capacitors are necessary for both differential and single-ended mode for the AMP. So please try to add them in the application. We could help to review your desgin if you could show us your SCH.
    Best regards,
    Shawn Zheng
  • 0 in reply to Shawn Zheng
    Prodigy 250 points

    Thanks, I have today replaced this ic , but i am still not getting any sound in the speakers (tweeters) though now both sets of output pins show 7.6 volts with speakers connected.

    As I had mentioned earlier previously the smps used to go to zero volts when speakers were connected, this is not happening now, with the new ic.

    I am able to trace the audio into the input of the ic.

    Unfortunately I do not have a schematic of this set.

    With best wishes.

    Satya

  • 0 in reply to satya dutt
    Prodigy 250 points

    I forgot to mention that I tried to measure voltage at fault, mute and shutdown it shows zero volts. I tried to give voltage at shutdown but did not have any luck.

    The voltage at vreg shows 4 volts.

    With best wishes.

    Satya

  • 0 in reply to satya dutt
    TI__Mastermind 24835 points
    Hi Satya,
    THe /Shutdown pin should be in High voltage to make the AMP device work normally.
    Best regards,
    Shawn Zheng
  • 0 in reply to Shawn Zheng
    Prodigy 250 points

    Hello Shawn,

    Thanks, I made a mistake and can read about 3.1 volts on the shutdown, not sure if this is still too low.

    With best wishes.

    Satya

  • 0 in reply to satya dutt
    TI__Mastermind 24835 points
    Hi Satya,
    3.1V should be high enough. Could you please show me the SCH?
    Best regards,
    Shawn Zheng
  • 0 in reply to Shawn Zheng
    Prodigy 250 points

    Hello Shawn,

    Unfortunately I do not have a schematic. Also wanted to ask you the voltage on ROSC is 1.7 and shows a resistance of about 35 K. The VBYP shows 1.2 volts.

    I think the speakers pinout voltage which show about 7.6 on both are a little low, I believe it should be half of powers supply.

    With best wishes.

    Satya

  • 0 in reply to satya dutt
    TI__Mastermind 24835 points
    Hi Satya,
    It's very hard to debug without SCH file. The 1.2V voltage on the VBYP looks reasonable. We usually use 100kOhm resistor for the ROSC to get a 217~294kHz PWM frequency. In idle state, the DC level on the output pins is expected to be PVCC/2.
    Best regards,
    Shawn Zheng
  • 0 in reply to Shawn Zheng
    Prodigy 250 points

    Hi Shawn,

    I am getting about 11.7 volts on BSRP, BSLP etc. and only 7.6 on the output pins. Is the voltage for BSRP etc. OK?

    Best regards.

    Satya

  • 0 in reply to satya dutt
    TI__Mastermind 24835 points
    Hi Satya,
    Are you using PVCC=24V power supply? If yes, the Vbst=11.7 is quite low. Did you measure the waveform on the output pins? It's expected to be PWM with 50% duty-cycle in idle status and the amplitude is close to PVCC.
    Best regards,
    Shawn Zheng
  • 0 in reply to Shawn Zheng
    Prodigy 250 points

    Hi Shawn,

    You are right the supply voltages is 24. I do not have a scope to check the waveform.

    Can you tell me what should be the voltage at MSTR/SLV if I want to run it by itself, as master?

    Kind regards

    Satya

  • 0 in reply to satya dutt
    TI__Mastermind 24835 points
    Hi Satya,
    Usually the MSTR/SLV pin is set to High voltage to enable master mode.
    Best regards,
    Shawn Zheng