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PCM1865: 25dB gain issue

li darren
Intellectual 520 points

Part Number: PCM1865

Hi,

I used PCM1865 in MIC input design, 100mV input, I set 20dB gain in PCM1865, DA output is ok, but I set 25dB gain, output wave is not ok, as following picture shows. by the way, DA is 0dB gain, if I adjust DA gain, there is on issue. So, can PCMd1865 not be set so much gain?

  • 0
    TI__Expert 5645 points

    Hi Li,

    The input signal of 100mV for mic input w. 25dB gain should not cause any issue as there is enough head...I will replicate the same test condition in the lab here and will let you know the results but would you be able to share more details as far as diff/SE mode and other configuration details for your testing.

    Thanks.

    Best regards,
    Ravi

  • 0 in reply to li darren
    Intellectual 520 points

    this is config file,

    unsigned char reg[1] = {0x00};
    reg[0] = 0xff;
    _write_pcm1865(reg, 0x00, 1);
    delay_ms(5);
    _read_pcm1865(reg, 0x00, 1);
    delay_ms(5);

    reg[0] = 0x00;
    _write_pcm1865(reg, 0x00, 1);
    delay_ms(5);
    _read_pcm1865(reg, 0x00, 1);
    delay_ms(5);

    reg[0] = 0x11;
    _write_pcm1865(reg, 0x20, 1);
    delay_ms(5);
    _read_pcm1865(reg, 0x20, 1);
    delay_ms(5);

    reg[0] = 0x07;
    _write_pcm1865(reg, 0x26, 1);
    delay_ms(5);
    _read_pcm1865(reg, 0x26, 1);
    delay_ms(5);

    reg[0] = 0x3F;
    _write_pcm1865(reg, 0x27, 1);
    delay_ms(5);
    _read_pcm1865(reg, 0x27, 1);
    delay_ms(5);

    reg[0] = 0x03;
    _write_pcm1865(reg, 0x0b, 1);
    delay_ms(5);
    _read_pcm1865(reg, 0x0b, 1);
    delay_ms(5);

    reg[0] = 0x01;
    _write_pcm1865(reg, 0x0c, 1);
    delay_ms(5);
    _read_pcm1865(reg, 0x0c, 1);
    delay_ms(5);

    reg[0] = 0x00;
    _write_pcm1865(reg, 0x0d, 1);
    delay_ms(5);
    _read_pcm1865(reg, 0x0d, 1);
    delay_ms(5);

    //reg[0] = 0x40;
    reg[0] = 0x40;
    _write_pcm1865(reg, 0x06, 1);
    delay_ms(5);
    _read_pcm1865(reg, 0x06, 1);
    delay_ms(5);

    // reg[0] = 0x46;
    reg[0] = 0x46;
    _write_pcm1865(reg, 0x07, 1);
    delay_ms(5);
    _read_pcm1865(reg, 0x07, 1);
    delay_ms(5);

    reg[0] = 0x41;
    _write_pcm1865(reg, 0x08, 1);
    delay_ms(5);
    _read_pcm1865(reg, 0x08, 1);
    delay_ms(5);

    reg[0] = 0x41;
    _write_pcm1865(reg, 0x09, 1);
    delay_ms(5);
    _read_pcm1865(reg, 0x09, 1);
    delay_ms(5);

    reg[0] = 0x00;
    _write_pcm1865(reg, 0x01, 1);
    delay_ms(5);
    _read_pcm1865(reg, 0x01, 1);
    delay_ms(5);

    reg[0] = 0x00;
    _write_pcm1865(reg, 0x02, 1);
    delay_ms(5);
    _read_pcm1865(reg, 0x02, 1);
    delay_ms(5);

    reg[0] = 0x00;
    _write_pcm1865(reg, 0x03, 1);
    delay_ms(5);
    _read_pcm1865(reg, 0x03, 1);
    delay_ms(5);

    reg[0] = 0x00;
    _write_pcm1865(reg, 0x04, 1);
    delay_ms(5);
    _read_pcm1865(reg, 0x04, 1);
    delay_ms(5);

  • 0 in reply to li darren
    TI__Expert 5645 points

    Thanks for providing the additional details. I'll review the SCH and look at the configuration details to run the tests on EVM. I should get back w. you following the testing on my end and SCH review 

    Best regards,
    Ravi