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TAS5825M: TAS5825M FSMODE selection

Kazuki Kuramochi
Genius 10785 points
Part Number: TAS5825M


Hi professional,

My customer has question for TAS5825M's FSMODE resister.

Datasheet p48 Table 11. SIG_CH_CTRL Register Field Decrictions said "Need set it manually If the input Fs is 44.1kHz/88.2kHz/176.4kHz".

Is this meaning we couldn't use Auto detection for 44.1kHz/88.2kHz/176.4kHz digital audio signal input and must need to configure FSMODE manually?

Do you have any way to use Auto detection for 44.1kHz series input signal?

By the way, datasheet table11 mentioned FSMODE has 1bit in 0x28 for configuration. However FSMODE need 4bit for configuration. In PPC3, FSMODE has 4bit (3~0) in 0x28.

I think datasheet is typo and PPC3 is correct. Is this right?

I'm looking forward hearing back from you.

Best regards,

Kazuki Kuramochi

  • 0
    TI__Expert 6720 points

    Hi Kazuki,

    The reason for "Need set it manually If the input Fs is 44.1kHz/88.2kHz/176.4kHz" is that TAS5825 does not make a difference with 48kHz & 44.1kHz, 96kHz & 88.2kHz... which means the PLL frequency factors are the same.

    It's highly suggested to keep these bits to default Auto detection configuration if you do not mind the PWM switching frequency varies between 384kHz & 354.2kHz.

    Regarding the register description, you are correct. Please follow PPC3 four bits.

    Rdgs,

    Matthew

  • 0 in reply to Matthew Miao
    TI__Genius 10785 points

    Hi Matthew,

    Thank you very much for your prompt reply.

    Is your description's meaning that FSW will be 384kHz when we input 48kHz and will be 352.8kHz when we input 44.1kHz?(If we set FSW_SEL(2h) to 384kHz) In other words, does  FSW will be 384kHz if we set 44.1kHz on FSMODE manually?

    Best regards,

    Kazuki Kuramochi

  • 0 in reply to Kazuki Kuramochi
    TI__Expert 6720 points

    Hi Kazuki,

    Even manually setting to 44.1kHz, the PWM output frequency is still 352.8kHz. Because internal only has 8 times option.

    The motivation of this registers setting for 44.1k is to have the capability for EQ bank. (different EQ parameters for 48k and 44.1k). However, final TAS5825M can't automatically switch EQ. The only option is 2 Band DRC & AGL flow supports manually EQ bank switch.

    Rdgs,

    Matthew