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Original question:

TPA3116D2: drawback if not using SYNC in application with two amps

TPA3116D2: Two amps in master mode - Request for clarification on conflicting information given in forum

Fabian Knutti
Prodigy 30 points

Part Number: TPA3116D2
Other Parts Discussed in Thread: TAS5760M,

The related thread describes the usage scenario of two TPA3116 on the same board but with different supplies. TI's answer on whether configuring the two amps in master mode was:

"If the devices PWM switching frequency are same, that's fine to configure all devices to master."

so it basically suggests to use the same PWM frequency on both amps when not synchronized.

The thread "TAS5760M: SYNCing a TAS5760M with a TPA3116D2?" is about choosing the PWM frequency for two amps that are not synchronized (Namely a group of synchronized TPA3116 and the TAS5760). The suggestion there is just the opposite. Namely TI's advise is to configure the PWM frequencies such, that the difference doesn't fall within the audible spectrum, i.e., well greater than 20kHz.

For me, this just adds to the confusion. Therefore what I would really appreciate your advise on is, if two TPA3116 are used on a single PCB, unsynchronized, i.e., both in master mode, but with with separate power supplies

1. Is this feasible

2. What is your suggestion regarding the choice of PWM frequency on the two amps? Same or suffciently different?

Thank you in advance and best regards,

Fabian

  • 0
    TI__Expert 6295 points

    hello Fabian,

      for 2x TPA3116, if it is synchronized or not synchronized, what issue you may meet in your application? its EMI related or something else?

    regards

    Linda

  • 0 in reply to Xiaolin Qin
    Prodigy 30 points

    Hello Linda,

    Thank you for your reply.

    I'm primarily concerned regarding the audible beats noise issue mentioned in the datasheet. As I understand the datasheet, suppressing audible beats noises is the main purpose of the sync input/output?

    Best regards,

    Fabian

  • 0 in reply to Fabian Knutti
    TI__Mastermind 19950 points

    Hi Fabian,

    The Sync is used for PWM switching frequency synchronization when several device used on one board.

    It can not generate noise.

    Regards,

    Derek  

  • 0 in reply to Yanming Gong
    Prodigy 30 points

    Hi Derek,

    Thank you for your reply.

    What you are saying, corresponds to my understanding, since I cannot see how two devices playing the same audio signal could lead to audible beats noise, just because their PWM signals are not synchronized. Therefore your statement 

    Yanming Gong said:

    It can not generate noise.

    makes sense to me. The datasheet of the TPA3116D2 however reads:

    "The device can be configured for either master or slave operation by using the SYNC pin. This helps to prevent audible beats noise."

    which is what created the confusion in the first place. So if this audible beats noise issue does not exist, I suggest to remove this sentence from the datasheet to prevent confusing more people?

    Best regards,

    Fabian