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TAS5411-Q1: Short load detection and fault state

na na78
Guru 16770 points
Part Number: TAS5411-Q1


Hi

Our customer is facing a issue for short load detection.

Short across load detection during load diag after de-assertion of STANDBY can work.

If load is shorted in play mode (output is switching with audio), a device can go into fault state (overcurrent protection).

After fault detection, the device should go into load diag mode, but short across load is not detected in high probability.

So we have questions as follows.

1.  

How to detect short load threshold (0.9ohm) during load diagnostics?  

What is DC bias at output while load diagnositc? 

2.

Is there any difference of load diagnostics sequence between de-assertion of standby and going into fault state?

Or should both cases follow the Figure 11?

3.

Is there possibility of impact for load diag by overcurrent fault?

BestRegards

  • 0
    TI__Expert 6985 points
    Hello, Gregg will take a look at your question. Thanks, Jeff
  • 0 in reply to Jeff Kohnle
    Genius 4175 points

    Hello Jeff-san and Gregg-san,

     

    This application uses 4th order LPF total 4.4uF capacitor across GND same as another sled TAS5411-Q1: Load Diagtopic.

    On TAS54x4C design guide SLOA196 Page14 Fig7 shows below sequence at load diag.

    Here is one assumption, if large cap insist to detect status as Open load before move to Short load test phase then it cannot report Short load and keep output the signal. Is that case?

     

    Regards,

    Mochizuki

     

  • 0 in reply to Mochi
    TI__Mastermind 45085 points

    Mochizuki-san,

    The 4.4uF violated the maximum capacitance on the OUT_X pins.  See table 6.3 in the datasheet, third item from the bottom.  This capacitance is not allowing for the load diagnostics to ramp correctly and provide a proper test.

  • 0 in reply to Gregg Scott
    Genius 4175 points

    Hi Gregg-san,

     

    Thank you for your reply, we recognized our customer used just above the recommended capacitor value.

     

    We will ask them to change value and see improvement of diag accuracy.

     

     

    Regards,

    Mochizuki