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TPA3116D2 SYNC frequency

toshi-e2e
Genius 4830 points
Other Parts Discussed in Thread: TPA3130D2

Hi! all,
When using two units of TPA3116 as a master and a slave mode,
what is the relationship of the frequency of the fOSC setting and SYNC output?

When OSC is set to 400kHz, SYNC out is 100kHz.
Is 100kHz a PWM frame frequency?
Also, according "Figure 37. Schematic" of the datasheet on Page 26, there is a low pass filter between a SYNC output and a SYNC input.
And the cutoff frequency is about 15.9kHz. It seems too low cut off frequency against the SYNC out frequency,
How is the cutoff frequency determined?

Regards,
Toshi

  • 0
    TI__Mastermind 37045 points

    Hi Toshi-san,

    PWM output freq is 4x SYNC freq default (but also depends on the AM pins settings). SYNC input freq is 100KHz nominal.

    Please refer to the EVM user's guide for recommended RC values (4.7K ohms and 4.7P Farad). I think Fig 37 has a typo. 1nF should be 1pF instead.

    reg,

    Paul.

  • 0 in reply to user5276421
    Prodigy 50 points

    I confirmed this on my scope today, as I'm in the middle of a multi-channel design with the TPA3130D2. I'm wondering if I can use an external 100kHz oscillator for driving the sync pins, as it will make the PCB layout easier since all channels will be the same. I'm planning to use 8 of these chips and would like them all synchronized.

    I also noticed the SYNC output on the EVM has an almost triangular wave shape. Is this to reduce audible noise on the input lines, or is there another reason behind it?