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TAS6421-Q1: TAS6421-Q1

user6286721
Prodigy 30 points
Part Number: TAS6421-Q1

Hello, I am using TAS6421-Q1 in my project. I am playing sound via I2S. I have some problems. I dont use external MCLK. I connected BCLK and MCLK together. 

1) Playing sound has too much noise. And I got too much clip error because of this problem. About this problem I put  series 500R resistor on I2S data line. Noise decreased but not gone. Also volume is decreased. 

I tried to put pull Up/down resistors but noise didnt changed. what should I do about noise problem?

2) While playing ( also in MUTE mode) there is another noise at background ( like sound "sssssssssssssssssss") This noise is always same. I think output swithcing frequency causes this problem but I am not sure. 

  • 0
    TI__Genius 9140 points

    under I2S mode, you can not simply connect BCLK with MCLK.  MCLK should be >=6.144MHz, please check that.  the noise shows your AMP is not playing music at all.

    Dylan

  • 0 in reply to Dylan Yao
    Prodigy 30 points

    Hi Dylan,

    Thanks for reply.

    I solved 2nd problem. it was caused because of output frequency. I changed Miscellaneous Control 2 Register bit from 0x62 to 0x72. ( 111: 48 × fS (2.12 MHz / not supported)  ) and 2nd problem is solved.

    for first problem: 

    I am using s32k148 evb  and there is not MCLK output. and its writen " 

    In TDM mode SCLK and
    MCLK can be connected together. If SCLK and MCLK are connected together or the frequency of SCLK and
    MCLK is equal, FSYNC should be minimum 2 MCLK pulses long.

    in datasheet. So I tried connect MCLK and BCLK together in I2S mode. 

    İf I put 500R-1K on data line, the noice is decreasing. 

    How can i use  TAS6421-Q1 without MCLK. 

  • 0 in reply to user6286721
    TI__Mastermind 34305 points

    You must have a MCLK in all cases.  Just in the special TDM input case, can the MCLK and SLCK be tied together with the same clock.