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TAS5805M: False overcurrent trigger happened occasionally in PBTL mode

Zhanpeng Li
Intellectual 2140 points
Part Number: TAS5805M
Other Parts Discussed in Thread: TAS5805, TAS5825M

Hi team,

this is brandon. we met some problems in debuging TAS5805M.

Our project uses the TAS5805 amplifier. When playing songs at the maximum volume, over-current protection is occasionally triggered. Could you help give some suggestions on this?
Two power amplifiers, one of which is U100, BTL mode is connected to intermediate frequency SPK, connected in series with 3.3uF followed by high frequency SPK. Another U200, PBTL mode is connected to low frequency SPK.

The phenomenon is as follows: I tried two machines. When playing <the ferry>, there was 1 out of 10 times that triggle the false overcurrent protection. At a certain point in the playback process, the low-frequency SPK BOX stopped sounding. Will not recover by itself. Press stop on the menu, and then the playback will ring again. The software reads the register to show the overcurrent protection.

Below are some tests on my side for reference.

1. On the low-frequency power amplifier 16V stabilized capacitors C201, C202, the voltage ripple of the flying line does not exceed 500mV at the Ferry and Hotel California

2. In the mid-high frequency power amplifier 16V voltage stabilized capacitors C104, C105, the voltage ripple of the flying line does not exceed 500mV at the Ferry and Hotel California

3. Add the L flying lead of the LC output from the power amplifier and the current clamp to measure the maximum current at low frequency L200. Ferry 1.08A California Hotel 1.46A The waiting game 1.55A life is wonderful 1.5A

4. Add the L flying lead of the LC output from the power amplifier to the current clamp and measure the current to capture the maximum value at the intermediate frequency L102. Ferry 1.61A California Hotel 2.02A The waiting game 2.32A life is wonderful 2.2A

could you help give some guide on this?

layout截图.zip

MEISSA_MINI2_AUDIOPA_H103_200629.pdf

BR

Brandon.

  • 0
    TI__Genius 9995 points

    Hi Brandon,

    For both TAS5805 and TAS5825, please try to change all the 0.22uF BST cap to 0.47uF. Then try again to see whether this issue is eliminated or not.

    For TAS5825M, datasheet indicates a 0.47uF rather than 0.22uF.

    BR,

    Alix Wan.

  • 0 in reply to Alix Wan
    TI__Intellectual 2140 points

    Hi Alix,

    we change the BST CAP from 0.22uf to 0.47uf, the issue could be solved in some song play and from our statistics,The probability of false triggers has decreased, but still will happened in some song.

    from our experiment, this situation would cause the trigger easier.

    the green one is the supply votage;

    the yellow one is the voltage on BST Cap;

    the pink one is the current on L200;

    could you kindly give me more insight on this?

    BR

    Brandon

  • 0 in reply to Zhanpeng Li
    TI__Intellectual 2140 points

    Hi Alix,

    could you give us more insights on this?

    BR

    Brandon

  • 0 in reply to Zhanpeng Li
    TI__Genius 9995 points

    Hi Brandon,

    From the waveform, i see not big current spike that may trigger OCT (7.5A). You can configure GPIO as fault by setting eg. GPIO0:

    w 98 00 00

    w 98 7f 00 book 0;

    w 98 60 01 #GPIO 0 as output

    w 98 7f 0B #GIOP as fault, note need a pull up resistor

    Then you can use the fault to trigger to capture waveform of: BSTA+ , BSTB+, BCLK, GPIO0

    BR,

    Alix Wan.