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TAS5616 in a noisy 12v environment

Nick52556
Intellectual 280 points
Other Parts Discussed in Thread: TAS5414A, TAS5508B, TAS5086

Hi,

I am looking to use the TAS5616 in an automotive environment which limits me to a noisy 12v to 14v power supply signal. The chip says it requires a 50v input which according to the spec video is for high power output correct? Would it work ok to use a 12v to 50v boost converter to power a chip like this? Would the ripple be too much in the system? Are there other chips out there more purpose built for the application?

  • 0
    TI__Mastermind 18510 points

    Nick, you could use TAS5616 with a boost converter, but ripple and noise would depend on the quality of the boost converter.  TAS5616 requires power supply DC between 25 and 50 V.  At 50V it can output 160W per channel stereo into 8ohm loads.

    However, we have other chips that are designed directly for automotive applications.  What are your power targets (output power, load impedance, number of channels), assuming typical 12 to 14 V car battery supplies?  I'll try to suggest some chips.

    Best regards,

    Steve.

  • 0 in reply to SteveCrump
    Intellectual 280 points

    I would like the highest output power possible. At least 100W per channel.

    If I use the TAS5616, what is the maximum ripple voltage that it can filter out? Is there a preferred switching frequency when dealing with this chip? I would love to use a chip designed for automotive environments, but the ouptut powers have seemed meek so far.

  • 0 in reply to Nick52556
    TI__Mastermind 18510 points

    Nick, we have chips like TAS5414A and TAS5424A that are designed for operation from battery voltages.  These are 4-channel amplifiers, but it is possible to parallel pairs of outputs to provide a stereo output at 45W/channel into 2ohm loads.  You might want to look into those.

    However, if 100W per channel stereo is mandatory (into 8ohms minimum speaker impedance rating for TAS5616), you will have to use a device like TAS5616 with a boost converter.  You will need 39 or 40 Vdc at TAS5616 from the converter for 100W at 10% THD.

    How much ripple the converter can produce depends partly on your audio quality requirements.  In any case I would advise that RMS total ripple should be a couple of hundred mV maximum.

    Converter frequency could be important because of potential for audio-frequency beats between its switching and TAS5616.  Maybe you can sync TAS5616 to the converter or vice versa.  I expect you will place a TAS5508B or similar modulator on the PCB with TAS5616, as in the EVM.  It's better to send digitally encoded audio around a car than PWM signals.  Other electrical signals in a car can easily interfere with PWM edges, and this can modulate PWM duty cycles, causing distortion and/or noise.

    Best regards,

    Steve.

     

  • 0 in reply to SteveCrump
    Intellectual 280 points

    Thankyou, that is what I figured, just wanted clarification.

     

    I will be using a TAS5086 for the PWM processing into the TAS5616. What do you mean by "syncing" the TAS5616 to the SMPS?

     

    Also I had a question about the TAS5086. It says that the chip can provide a stable clock section by using the internal oscillator clock when MCLK is absent or unstable. Does this mean a design can not use the MCLK and have the chip internally provide it? Or must a 64fs clock be given to the external pin?

     

  • 0 in reply to Nick52556
    TI__Mastermind 18510 points

    Nick, to avoid beats between the boost converter and the class-D amplifier, it's wise to make one of the switching frequencies an integer multiple of the other.  This eliminates difference frequencies that could be audible in the audio range.

    I am checking about TAS5086.  I think you are asking if TAS5086 can generate MCLK for the system, maybe so you can simplify your circuit.  Did I understand that correctly?

    Best regards,

    Steve.

  • 0 in reply to Nick52556
    TI__Mastermind 18510 points

    Nick, TAS5086 does not provide an output from its internal oscillator, so an external MCLK must still be provided.  The internal oscillator provides the functions described on page 10 of data sheet SLES131C.

    Best regards,

    Steve.