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TPA3255-Q1: synchronizing with an external processor

Part Number: TPA3255-Q1

Hello,

I was wondering if it was possible to synchronize the PWM chopping frequency with an external processor.
I saw there is a slave input that can be selected synchronized through OSC_IOM.
My Idea was to synchronize the chopping frequency to minimize noise by supplying the OSM_IOM frequency.
Can it work? If yes what is the relationship between the synchronization frequency and the PWM chopping frequency.
Also what is the range of allowable frequencies?

  • Hi Daniel,

    I'd recommend taking a look into section 9.2.1.2.4 Oscillator of the datasheet. Your plan should work as long as you take into account any phase delays on the output due to operating the device in slave mode. 

    The oscillator frequency needs to be between 2.58MHz - 5.75MHz. The oscillator frequency (Fosc) relationship with the PWM frequency (Fpwm) is Fosc = Fpwm*6.

    Best Regards,

    Robert Clifton

  • Hello Robert,

    Thank you for your quick answer.
    I wanted to know if it was possible to synchronize the PWM chopping signal with  409.6KHz. The frequency of Fosc would then have to be 2.4576MHz which is 130KHz lower than what is allowed.


    Would it still work? I am only interested in producing sub 1KHz signals. I just want to know if the reason is that it will reduce audio quality at higher frequencies or if there is a hardware limiting factor as to why it can not be lower.

  • Hi Daniel,

    We wouldn't be able to guarantee any of the device performance specs but the device should theoretically still work. Just be aware that you might see THD+N not be as low at about 400kHz. 

    Best Regards,

    Robert Clifton