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AIC3254 + TPA3110D2 "Click" when starting playback

Mario Raffin
Expert 2405 points
Other Parts Discussed in Thread: TPA3254, AM3358, TPA3110D2

Dear Support,

    my design exploits an AIC3254 codec with a TPA3254 classD amplifier. When I start playing, I get a annoying "click", caused by I DC step which I can see at the input if the amplifier (see picture below). I wonder if I missed something in the codec configuration. 

The signal outputs from the LOL pin of the codec, it is coupled with a 4.7uF, filtered by an RC (R 100ohm, C 100nF between signal and ground) before entering in the ampli. 

The big problem is that this DC is detected by the TPA3254 amplifier which goes in FAULT condition.

Thank you.

  • 0
    TI__Guru* 84915 points
    Hello, Peregrinus,

    Could you provide more information about this issue, please? Could you provide a schematic and register configuration? Additionally, does this "click" appear only on the DC step or can it be heard all the time? Also, could you give more details about this DC step? How is it generated?

    Thank you.

    Best regards,
    Luis Fernando Rodríguez S.
  • 0 in reply to Luis Fernando Rodriguez S.
    Expert 2405 points

    Thank you for the reply Luis,

        below you can find more datails about the schematic af the codec section, the amplifier section, and a codec register dump before and after the aplay command (the codec is connected to a Sitara AM3358 processor).

    I experience the problem as soon as I enable the amplifier with the SD pin and it goes immediatly in fault condition which can not be recovered with and SD cycle (short circuit fault) but only with a power cycle (DC component fault).

    Sometime I can enable the apli with not fault. In this case I can hear the click the first time I start playing an audio file (aplay command), then the following aplay commands does not generate any click but if I wait some minute and I play a sequence I get the click. 

    I assume the click is caused by the following reason: the voltage at the input of the amplifier TPA3110D2, on the right side of R50 in the picture below, is about 3V. During silence the output of the codec is floating, when codec inner mux enables the output, the voltage is set to 800mV and a step of -2.2V is generated at the input of the TPA3110D2. This step produces a DC component which causes the fault of teh ampli. 

    I have to say I have used the AIC3254 with other amplifiers and I didn't experienced this problem. 

    Regards,

    mario

    Fullscreen dump_silent.txt Download 
    PAGE0
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f    0123456789abcdef
00: 00 00 60 00 00 11 04 00 00 00 00 01 01 00 80 02    ..`..??....??.??
10: 00 08 01 01 80 01 00 04 00 00 01 4c 00 08 01 00    .?????.?..?L.??.
20: 00 00 00 00 44 00 00 00 00 00 00 00 00 00 00 00    ....D...........
30: 00 00 00 00 00 12 03 02 02 00 00 00 01 01 00 14    .....????...??.?
40: 00 f9 f9 00 6f 38 00 00 00 00 00 ee 10 d8 7e e3    .??.o8.....???~?
50: 00 00 00 06 06 00 00 00 00 00 00 00 00 00 00 00    ...??...........
60: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
70: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
90: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................

PAGE1
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f    0123456789abcdef
00: 01 00 01 00 00 00 00 00 00 00 00 10 08 08 08 08    ?.?........?????
10: 3c 3c 0e 0e 00 00 00 00 00 00 00 00 00 00 00 00    <<??............
20: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
30: 00 00 00 00 44 00 44 40 00 50 00 32 32 00 00 00    ....D.D@.P.22...
40: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
50: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
60: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
70: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
90: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................

    Fullscreen dump_playing.txt Download 
    PAGE 0
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f    0123456789abcdef
00: 00 00 60 00 03 a1 07 1a 90 00 00 8f 81 03 00 02    ..`.?????..???.?
10: 00 08 ad 84 40 01 00 04 00 00 01 4c 00 01 98 00    .???@?.?..?L.??.
20: 00 00 00 00 00 ee 11 00 00 00 00 00 c0 00 00 00    .....??.....?...
30: 00 00 00 00 00 12 02 02 02 00 00 00 01 01 00 d4    .....????...??.?
40: 00 f9 f9 00 6f 38 00 00 00 00 00 ee 10 d8 7e e3    .??.o8.....???~?
50: 00 00 00 06 06 00 00 00 00 00 00 00 00 00 00 00    ...??...........
60: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
70: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
90: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................

PAGE1
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f    0123456789abcdef
00: 01 00 01 00 00 00 00 00 00 3c 00 10 08 08 08 08    ?.?......<.?????
10: 3c 3c 0e 0e 00 00 00 00 00 00 00 00 00 00 00 00    <<??............
20: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
30: 00 00 00 00 44 00 44 40 00 50 00 32 32 00 00 f0    ....D.D@.P.22..?
40: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
50: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
60: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
70: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
90: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................

  • 0 in reply to Mario Raffin
    Expert 2405 points
    The problem addesses mostly the amplifier, I found the solution in the audio amplifier forum:

    e2e.ti.com/.../514913

    Thank you for the support.