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TAS5411-Q1: Load Diag

na na78
Guru 16770 points
Part Number: TAS5411-Q1
Other Parts Discussed in Thread: TAS5414C

Hi

I have a question of Load diag.

According to datasheet, it says load diag test takes approximately 229ms to run.

I will include discharge (75ms), ramp up (52ms), check (50ms) and ramp down (52ms).

However, datasheet says if a fault is present or large capacitor to GND is present on output, check phase will repeat up to 5 times.

So if a fault is present during load diag, check phase (50ms) repeat 5 times additionlly and takes additional 50 ms x 5 = 250 msec?

If yes, total diag time will be 75 + 52 + 50*6 + 52 = 479 msec as maximum.  Is it correct?

BestRegards

  • 0
    TI__Mastermind 45085 points
    You are correct. The length of the time can increase by 200msec.
  • 0 in reply to Gregg Scott
    Guru 16770 points

    Hi Gregg

    Thank you for your reply.

    I found similar question as follows.

    e2e.ti.com/.../480949

    Let me confirm the following.

    In upper link, you answered the check phase will perform all 5 test in 50msec.
    Does it mean load diag can finish within 257 msec even if check is repeated up to 5 times?

    BestRegards

  • 0 in reply to na na78
    TI__Mastermind 45085 points
    Hi,
    I was mistaken as I thought you requested info on another device. My apologies. The correct answer is in the post you found.
  • 0 in reply to Gregg Scott
    Guru 16770 points
    Hi

    Thank you for reply.

    > I was mistaken as I thought you requested info on another device.
    Actually, the device which had been discussed in other post is different from TAS5411.

    Can we regard TAS5421 and TAS5411 are the same about load diagnostics function?

    After all, TAS5411-Q1 takes 257 msec as maximum for load diagnostics. Is my understanding correct?

    BestRegards
  • 0 in reply to na na78
    Genius 4165 points
    Hello Gregg-san,

    Here is related question, because our customer used 4th order LPF configuration 15uH+2.2uF and 15uH+2.2uF.
    So total capacitance from output pin to GND is 4.4uF, it is quite large. What is limitation of the capacitance to keep accurate load diag function on TAS5411?
    In TAS5414C design guide SLOA196 page14, it said
    "The need for the longer duration allows for larger common mode capacitors in the output filter. To prevent
    false or inconsistent short indications the total capacitance on each output pin to ground for the S2G and
    S2P should not exceed 680 nF."

    If after 5 times "50msec check phase" trial and timeout, but there is still large error occurred caused by large capacitance on TAS5411 system, then which diag status report will be out? Open Load?

    Regards,
    Mochizuki
  • 0 in reply to Mochi
    TI__Mastermind 45085 points
    There are several threads on this subject. The 4.4uF violates the absolute max specification in table 6.3.
  • 0 in reply to Gregg Scott
    Genius 4165 points

    Hi Gregg-san,

    TAS5411EVM is arrived in our lab and checked Diagnostics functions. Here is our findings at 4ohm load 14.4V Vdd.

     

    1. After start Diag sequence, sound is out with 1.2sec delay even without retry Diag sequence as below waveform.

            What is cause of this latency on TAS5411EVM/GUI setup?

     

    2. Increased Vdd to 17.3V, GUI cannot finish Diag sequence, retry Diag with 1.2sec cycle. Register showed "Over current shutdown fault" and red LED is on.

            3.3uF LPF cap is stuffed on the EVM, is that still too large to complete accurate Diag function?

     

    3. Is there any workaround to improve response speed of Diag function and accuracy?

            To keep EMI characteristics, customer wants to keep enough LPF capacitance at least 4.0uF.

     

    Regards,

    Mochizuki 

    TAS5411 waveform.xlsx

     

  • 0 in reply to Mochi
    TI__Mastermind 45085 points

    Mochizuki-san,

    The waveforms that you provided in the document do not look correct.  I will take this offline so we can have a discussion on your test set up.