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TPA3112D1EVM: The EMV will not start up

Markus Fuchs
Prodigy 110 points
Part Number: TPA3112D1EVM
Other Parts Discussed in Thread: TPA3112D1

We want to use for an new produkt the Amplifier TPA3112D1PWPR to drive an 8Ω Horn speaker.

For testings and measurements we bought the EVM but we've got issues with powering it up.

Befor powering up with +24DC:

- set the jumpers: JP1, JP2, JP5.

- SD pin to GND (after power up i've got an high Signal +21VDC)

- 100K resistance betwen AVCC

- 1KHz 800mV on INP

The only output signal I've got is a little swing from 100mV.

Measured on the jumper JP1 i've got an high level from +21VDC.

Sometimes the AMP starts up, when i often plug and unplug the power supply or once i forgot to switch of the Powersupply and after 3 Hours it starts out of nowhere.

When it runs once there are no problems. Then when i switch off the supply for some seconds it will start instantandly with no issues.

  • 0
    TI__Mastermind 19410 points

    Hi Markus,

    The JP1 is out or in?

    Did you try to reduce PVCC and input signal level?

    Regards,

    Derek

  • 0 in reply to Yanming Gong
    Prodigy 110 points

    Hi Derek,

    JP1 is in but i've testet it also out

    Yes i've tried it with +10VDC PVCC and 200mV input signal.

    It started up with the first try so i've wanted to test it with +24VDC PVCC but nothing happened when i switch the power on.

    When i tested it again with +10VDC PVCC it never started again, so i've tested it with an another Board with an new TPA3112D1 on it but it didn't work.

    Did i over see a simple thing?

    Regards,

    Markus

  • 0 in reply to Markus Fuchs
    TI__Mastermind 19410 points

    Hi Markus,

    Did you monitor the Fault pin? Is it low?

    And please also check GVDD voltage, it should be 6.5~7.3V.

    Regards,

    Derek

  • 0 in reply to Yanming Gong
    Prodigy 110 points

    Hello Derek,

    The blue graph is the measure on JP1

    No my GVDD pin is at +4,8V ~ +5V (yellow)

    The timescale is as low as possibile

    Regards,

    Markus

  • 0 in reply to Markus Fuchs
    TI__Mastermind 19410 points

    Hi Markus,

    Are the JP3 and JP4 in or out?

    They should be in.

    And please check PWM output waveform without audio input.

    Regards,

    Derek

  • 0 in reply to Yanming Gong
    Prodigy 110 points

    Hi Derek,

    JP3 und JB4 are now in, but nothing changed.

    I also had to change the connection for the Speaker from the pin-header "Out" to the Test plugs "Out-" and "Out+".

    There is no PWM-Output or other Signal on the Out Pins 23,25 / 21,17 they are straight on 0V like GND (measured no connection to GND).

    Regarts,

    Markus

  • 0 in reply to Markus Fuchs
    TI__Mastermind 19410 points

    Hi Markus,

    The device is not switching.

    To check the root cause, I suggest you can simplify the circuit. Remove the LC filter, OUT the JP1, remove the input source.

    Check the pins one by one. Focus on the PVCC, SD, Fault, AVCC, PLIMIT, GVDD, PWM out.

    Regards,

    Derek

  • 0 in reply to Yanming Gong
    Prodigy 110 points

    Hi Derek,

    I only have the FB1 and FB2 soldert on the output, no input signal and the jumper JP1 is out.

    PVCC:   +10,5V

    SD:        +10,5V

    Fault:     0V

    AVCC:   +6,2V (looks like an sawtooth signal from +5,1V to +6,2V)

    PLIMIT: +5,4V

    GVDD:  +5,4V

    PWMout:0V

    Now the device does not "istantly" (i mean 2-4seconds) start up. It starts only when i trigger it. (this is easier since i remove the FB1A, FB2A, R9 and R12)

    It had let trigger when i measure with the probe or play with the input signal to GND.

    Regards,

    Markus

  • 0 in reply to Markus Fuchs
    TI__Mastermind 19410 points

    Hi Markus,

    AVCC must be same as PVCC.

    And there is fault happened.

    I suggest you check the AVCC problem firstly.

    Regards,

    Derek

  • 0 in reply to Yanming Gong
    Prodigy 110 points

    Hi Derek,

    I've got the problem, the Resistor R5 is normaly 10Ω.

    I Don't now how this can be. In both boards where solderd 10Ω from two different manufacturer but both have now a resistance >300Ω.

    When i exchange this weird Resistors, it starts up instantly with +10V and +24V.

    Any Idea why the value of the resistors have changed?

    Thank you very much.

    Regards,

    Markus

  • 0 in reply to Markus Fuchs
    TI__Mastermind 19410 points

    Hi Markus,
    I am glad to hear that you have fix the problem.

    I do have no idea why the resistor value is changed...

    Is the boards new ones? I think the EVM bom is no problem.

    Regards,

    Derek

  • 0 in reply to Yanming Gong
    Prodigy 110 points

    Hi Derek,

    yes i've found the problem.

    But every time when i am plug in the supply from +24V the resistor triggers like a fuse. No issues with +10V

    The 10Ω resistor got values over 2MΩ so i've solderd an 2 Watt resistor in but the resistor starts smoking.

    I think i am destroying the TPA3112D1 everytime when i am using +24V directly. 

    In the datasheet "A 10-μF capacitor the AVCCpin is adequate." but on the EVM-board is an 1μF solderd must this one get exchange?

    Is the 100kΩ resistor between pin7 and pin14 also a must with PVCC +24V?

    Regards,

    Markus

  • 0 in reply to Markus Fuchs
    TI__Mastermind 19410 points

    Hi Markus,

    R5 and C3 is the RC filter. Because when AMP switching, PVCC would have some noise and ripple. Adding RC filter can filter some noise and ripple. 

    That does not need add 100kohm between pin 7 and pin 14.

    Regards,

    Derek