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TAS5713 - Inconsistent Error reg answers

Erik Lundh
Prodigy 200 points
Other Parts Discussed in Thread: TAS5713

Hi!

I'm trying to debug a system based on a TAS5713 and a LM3S9B96, I've finally got the processor to output some I2S-data but I dont get any switching on the output of the amp. The amp is configured for BD-mode, and ASEL_FAULT as output. Fault isn't indicated but when I poll (after writing error reg with 0x00) I get different answers in a sequence:

Error: ff
Error: 30
Error: 30
Error: 30
Error: 30
Error: ff
Error: f0
Error: 97
Error: 01
Error: b8
...

I'm just polling the register a couple of times, and its the same sequence after a restart.

Any ideas? =)

  • 0
    Prodigy 200 points

    Additional information:

    I get this "error sequence" in both running and shutdown mode. The amp asserts FAULT low directly at exit shutdown, the supply voltage is 12V and there is a resistive dummy load at the output.

    I've noticed that there is a small peak at the output every 1s when in run-mode (not switching), could this be some sort Overcurrent thats kicking in?

  • 0 in reply to Erik Lundh
    TI__Mastermind 33420 points

    Hello Erik:

    Did you do an oscillator trim?  What is your initialization sequence?  Please also make sure that the I2S clocks are stable.

    Best regards,

    Tuan

  • 0 in reply to Tuan
    Prodigy 200 points

    Hi!

    Yes the oscillator trim should be done, and the clocks seems to be stable.

    My initialization sequence is (pseudo code):

    Drive PDN High

    Wait 1ms

    Drive RESET high

    Wait 14ms

    Run Oscillator Trim

    Wait 50ms

    Configure ASEL as Fault

    Configure ICD Registers for BD Modulation

    Configure mux Register for BD Modulation

    Exit shutdown

    Wait 200ms

  • 0 in reply to Erik Lundh
    Prodigy 200 points

    Replaced the board and now It starts switching atleast. But the switching frequency isn't properly filtered out, there is a 4Vpp ripple on the output (I'm using 10uH inductors and 680nF capacitors)

    The polling error reg answers is still the same even though it now is running.

  • 0 in reply to Erik Lundh
    TI__Mastermind 33420 points

    Hello Erik:

    I am not sure if you clear out the error register by writing 0 before you read it back.

    What is your PVDD level and your load impedance?

    Thanks,

    Tuan

  • 0 in reply to Tuan
    Prodigy 200 points

    Yes, the register is written with 0.

    PVDD is 12V and the impedance is close to 8Ohms

  • 0 in reply to Erik Lundh
    Prodigy 200 points

    After a while I realized that I was using a AD-filter for the BD-modulation, information about the output filter in the datasheet maybe would be smart?

    Well, soldered in the SSTIMER cap and use the amp successfully in AD-mode...

     

    But still the main question remain, why does the error reg register errors when its running succesfully?

  • 0 in reply to Erik Lundh
    TI__Mastermind 33420 points

    Hello Erik:

    The TAS5713 is in an autodetect mode, meaning when the I2S clocks are good, it will run.  It won't report any faults unless there are some glitches in the clock or the ratio between Fs/MCLK and/or Fs/SCLK are not correct.  So when you clear the faults and then if the glitches are there, it will report again.  If you run sine wave through, do you see any discontinuity?

    Best regards,

    Tuan

  • 0 in reply to Tuan
    Prodigy 200 points

    Hi again!

    The thing is that it seems to be working just fine, I get a glitch free sinewave, but when I poll the error-register it indicates an error, and as you can se the response  isn't consistent.

    I'll try to check my code again.

    Greets, Erik