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Original question:

TPA0172 I2C issue - Not completing power up sequence

TPA0172: Powering Up Sequence issue

Paul Chacko
Intellectual 623 points

Part Number: TPA0172

Dear TI Team,

We are facing a problem with TPA0172. The power up sequence is not getting completed.

We have seen in another E2E thread that it may be the problem with the BYPASS capacitor at BYPASS pin.

We tried changing the by pass capacitor also tried a new part. But still the issue is not resolved.

Could you please help?

Thanks and regards,
Paul

  • 0
    TI__Genius 13610 points

    Hey Paul,

    Thank you for reaching out and sorry for the delay.

    Could you provide more details regarding the schematic and/or code associated with your power on sequence?

    Best,

    Carson

    Low Power Audio Applications

  • 0 in reply to Carson Allen
    Intellectual 623 points

    Dear Carson,

    Thanks for your response.

    Please find the attached Schematic portion.

    Code: I shall add it in the next message.

    Thanks and regards,

    Paul

  • 0 in reply to Paul Chacko
    TI__Genius 13610 points

    Hey Paul,

    I am not seeing your schematic. Could you please post again.

    Best,

    Carson

  • 0 in reply to Carson Allen
    Intellectual 623 points

    Let me try again Carson, There is no option in the reply to add attachment. I dragged and dropped in to the editing window and it had shown upload complete.

    Code:

    void initPowerAmp(void)
    {
        WaitforpowerUpSeq();
           
        if(writePowerAmp() != 0)
        {
            printString("Power amp configuration fail\r\n");
        }
        readPowerAmp();    
        printString("Codec power amp i2c success\r\n");
    }
    void WaitforpowerUpSeq(void)
    {
        printString("Waiting for power amp power up...\r\n");
        int i;
       
        while(1)
        {
        T1CON = 0x8030;
        TMR1 = 0;            
        while (TMR1 < DELAY);    
            wbuff[0] = 0x0f;
            wbuff[1] = 0x0f;
            wbuff[2] = 0x0f;
            wbuff[3] = 0x0f;
            wbuff[4] = 0x07;
            wbuff[5] = 0xe2;
            writePowerAmp();
            sprintf(msg,"Power amp Writing = %x %x %x %x %x %x \r\n",wbuff[0],wbuff[1],wbuff[2],wbuff[3],wbuff[4],wbuff[5]);
            printString(msg);
                   
            readPowerAmp();
            if(!(rbuff[4] & 0x80)){
                break;
            }
        }
        printString("Power amp power up complete\r\n");    
    }
    **I am not sure if the above schematic image is legible. If not could you please let me know how can I upload as a pdf attachment?
  • 0 in reply to Paul Chacko
    TI__Genius 13610 points

    Hey Paul,

    I will take a look at this and get back to you soon.

    Best,

    Carson

  • 0 in reply to Carson Allen
    Intellectual 623 points

    Hey Carson,

    Any update on this?

    We are waiting for your inputs.

    Thanks and regards,

    Paul

  • 0 in reply to Paul Chacko
    TI__Guru** 114295 points

    Hi Paul,

    I'm following up on this.
    Regarding bypass pin let me ask a couple things:

    • You mentioned you tried different capacitors, what values did you tried? What was the material? If you have part numbers it would be best.
    • How is bypass pin voltage looking during power up? Is it getting at VDD/2 or close to it? Is this a long ramping?
    • Have you tried forcing VDD/2 to bypass pin? Kind of trying to emulate the capacitor charging on this pin.

    In addition, have you tried disconnecting the device output from the next stage? Not sure if the output of the amp goes directly to a speaker or some other amplifier. Let's try to isolate only this device during debugging.

    Best regards,
    -Ivan Salazar
    Applications Engineer 

  • 0 in reply to Ivan Salazar
    Intellectual 623 points
    Ivan Salazar said:
    • You mentioned you tried different capacitors, what values did you tried? What was the material? If you have part numbers it would be best.
    • How is bypass pin voltage looking during power up? Is it getting at VDD/2 or close to it? Is this a long ramping?
    • Have you tried forcing VDD/2 to bypass pin? Kind of trying to emulate the capacitor charging on this pin.

    Dear Ivan Salazar,

    The values of capacitors were 0.47uF and 0.1uF. Tantalum and Ceramic capacitors.

    Bypass pin voltage was staying near to 300mV and it was not at all ramping up.

    We tried a voltage divider at bypass pin with 10K resistors. But still the powering up did not complete.

    We did not try connecting a regulated 2.5V output to this pin. Should we do that?

    Thanks and regards,

    Paul

  • 0 in reply to Paul Chacko
    TI__Guru** 114295 points

    Hi Paul,

    Yes, please try with an external supply to bypass pin. Want to check if forcing the voltage is working or not.
    In addition, could you also try different supplies for the device itself? Are you using a power supply onboard in the same system? Or some external bench supply?

    Best regards,
    -Ivan Salazar
    Applications Engineer