TLV320AIC3254: CC3200AUDBOOST POP Noise

Hi Diljith,

If we need to add the Schottky diode(http://www.ti.com/lit/slaa492a.)

Do we need to modify the following register?

AudioCodec_regWrite(TI3254_PWR_CTRL_REG, 0x08);  // Disabled weak connection of AVDD with DVDD
AudioCodec_regWrite(TI3254_LDO_CTRL_REG, 0x01);  // Over Current detected for AVDD LDO

BR

Trevor

Hi Diljith,

Regarding LDO Control Register(P1_R2), current we set to 0x01(00: DVDD LDO output is nominally 1.72V , AVDD LDO output is nominally 1.72V), but we measured the the voltage level, the AVDD = 1.683V and the DVDD = 1.69V.

we also measure the sequence for AVDD & DVDD, please see the following figure(the blue line is AVDD and the yellow line is DVDD):

# Without Schottky diode

# With  Schottky diode

Do you have any suggestions to us?

Thanks.

BR

Trervor

Hi Diljith,

Update some information for you.

Please see the following sequence for internal LDO. we found that the POP noise occurs in the yellow circle.

Do you have any suggestions to us?

BR

Trevor

Hi Diljith,

Regarding your headphone out sequence, the pop noise occurs in the following line :

# Power up HPL/HPR and LOL/LOR drivers

w 30 09 3C

Do you have any suggestions?

BR

Trevor

Hi Diljith,

We also checked the POP noise on the AIC3254 EVM, there are four POP noises on EVM.

The first one is to plug USB cable into EVM(Power on codec). The second one and third one are happen when using AIC3254 CS to load "High Performance Stereo Playback". The last one is unplug the USB cable from EVM(Power off codec).

We also conducted some experiments:

1. Regarding 2nd POP, we found the 2st POP is related P1R9.

2. Regarding 3rd POP, it is related to P1R20:

    If set to 2k resistance, 2nd POP & 3rd POP are very close

    If set to 25k resistance, 2nd POP & 3rd POP are far away.

    BTW, regarding 3rd POP, it only happens when a silent source is played.

Do you have any suggestions for us?

BR

Trevor

Hi Diljith,

Do you have any update?

BR

Trevor

Hi Trevor,

We can only minimize the pop through the de-pop register settings and sequencing the power-up of various elements in the signal chain; we cannot eliminate it. If you try to remove the de-pop setting (P1R20), you will find that the power-on pop (P1R9) will be much louder. So the overall strategy of the register writes that I shared is to minimize the pop. Would this level of pop be a matter of concern for your application?

I reviewed the results with and without the Schottky diode and I can see that the diode is supplying the voltage to AVDD after DVDD is powered up. So there should be a reduction in the pop. Were you able to measure pop with and without the diode?

Best Regards.

Hi Diljith,

As previous state, there are four POP noises on the EVM, could you observe this result?

Regarding remove the de-pop setting (P1R20), the 2nd & 3rd pop will be mixed together. so the pop will be much louder.

Currently, we are focusing on 1st & 4th pop noise.

Currently, we are focusing on the first and fourth popular noises. Regarding these two pop noises, I think it is related to power sequence.

As I know the EVM uses external DVDD & AVDD power supply and the CC3200AUDBOOST uses the internal DLDO and ALDO power supply. 

Regarding the Schottky diode, it should apply to internal DLDO and ALDO power supply. I don't understand why the EVM need to add the Schottky diode.

Anyway, could you provide your AVDD and DVDD sequence to us(waveform)? Could you also provide the your Schottky diode(part number / DS)?

About 4th pop noise, could you provide the register setting for power off?

Thanks.

BR

Trevor

Hi Diljith,

Thanks for your power off sequence, we will try it later.

Regarding "http://www.ti.com/lit/slaa492a.", there are two power supply sequences in this app note(section2 & section3).

Our customer board(design reference cc3200audboost), default use internal DLDO and ALDO. The AIC3254 EVM use external DVDD & AVDD.

We also change our design to use external DVDD & AVDD. we can got the same result with AIC3254 EVM.

We can plot the signals sequence for you. What kind of power supply do you want to check(internal or external)?

BTW, as my previous post(Dec 28, 2020 8:28 AM), we have measured DVDD& AVDD sequence, you can check first.

Thanks.

BR

Trevor

I want to know where the pop is happening with respect to the AVDD and DVDD power-up signal. Also while powering down I would like to know where the exact pop is occurring. Just the AVDD and DVDD power up signal is not enough. Use the internal LDO mode (customer board) for the measurement.

Best Regards.

Hi Diljith,

We need some time to prepare the sequence for you(with internal LDO mode).

Do you have the AIC3254 EVM board? If yes, could you check whether it uses the external AVDD & DVDD? And could you check there are four POP noises on EVM?

The first one is to plug USB cable into EVM(Power on codec). The second one and third one are happen when using AIC3254 CS to load "High Performance Stereo Playback". The last one is unplug the USB cable from EVM(Power off codec).

BR

Trevor

Trevor,

You can do it on the customer board directly. No need to do it on the EVM.

Best Regards.

Hi Diljith,

We can't measure the POP signals with an oscilloscope.

Do you know how to use the oscilloscope to measure POP signals?

BR

Trevor

What is the difficulty that you are facing? You would need to trigger based on DVDD or IOVDD. Are you not able to capture the instance when pop occurs?

Best Regards.

Hi Diljith,

We use an scope probe to measure the headphone output, but when the pop noise appears, we can't see anything on the oscilloscope.

We doubt whether this is a pop noise. but we could confirm that we can hear the same sound on AIC3254 EVM.

Do you have the AIC3254 EVM board? If yes, could you check whether it uses the external AVDD & DVDD? And could you check there are four POP noises on EVM?

BR

Trevor

Hi Trevor,

I shall try to set up the measurement on the EVM later in the week and get back to you with the results.

Best Regards,

Hi Diljith,

Thanks for your help.

There are four POP noises on EVM. Please help us check whether it is the pop noise.

The first one is to plug USB cable into EVM(Power on codec). The second one and third one are happen when using AIC3254 CS to load "High Performance Stereo Playback". The last one is unplug the USB cable from EVM(Power off codec).

We also conducted some experiments:

1. Regarding 2nd POP, we found the 2st POP is related P1R9.

2. Regarding 3rd POP, it is related to P1R20:

    If set to 2k resistance, 2nd POP & 3rd POP are very close

    If set to 25k resistance, 2nd POP & 3rd POP are far away.

    BTW, regarding 3rd POP, it only happens when a silent source is played.

BR

Trevor

Hi Diljith,

Thanks for your help, we will will perform the measurement again according to your scope configuration.

Regarding your measurement, what does it mean "during codec power-up on the EVM"?

Is it equal to our first one pop noise?

We believe that adding a Schottky diode should avoid the first one noise. Do you have any comment for the second one pop noise?

BR

Trevor

Trevor,

The de-pop settings register is the TI3254_HP_DRV_START_UP_CTRL_REG register and you are already setting it in the configuration script.

What it the level of pop that you are seeing with the current settings?

Diljith