TAS5815: How to set the TAS5815 Clipper register

takeru ishibashi

Part Number: TAS5815

Tool/software:

Regarding the TAS5815, I have a question about the clipper function described in 3.8 Clipper in "TAS5815 and TAS5802 Process Flows".

When changing the clipper settings, I think the register values such as 0x18, 0x1C, and 0x20 in Book: 0x8C, Page: 0x2E will change, but I would like to know：
Are there any other register values that change?
How do the register values change depending on the clipper adjustment parameters?
What does each register bit adjust?

I would like to use the clipper function of the TAS5815, but would like to know the specific adjustment method.

Ishibashi Takeru

4 months ago

0 Ramsey Foote 4 months ago

TI__Genius 9175 points

Hi Ishibashi,

Registers 0x1C and 0x20 control the postscale gain for the left and right channels respectively. Register 0x18 controls the prescale gain. This app note describes the functionality of the blocks and parameters.

Regards,

Ramsey

0 takeru ishibashi 4 months ago

Prodigy 90 points

Thank you for your reply.
How does the register value (bit string) change when these gain values are changed?

Regards,

Ishibashi

0 takeru ishibashi 4 months ago in reply to Ramsey Foote

Prodigy 90 points

What is the status of this additional question?
Thank you for your response.

Regards,

Ishibashi

0 Ramsey Foote 4 months ago in reply to takeru ishibashi

TI__Genius 9175 points

Hi Ishibashi,

The registers will change as you modify the clipping level and makeup gain. In general, the prescale value increases as you decrease the clipper threshold and the post scale decreases in magnitude as you decrease the clipper threshold. You can use PPC3 to get exact values for different thresholds and use the document I mentioned earlier for how to convert between the pre and post scale to the clipper threshold and makeup gain..

Regards,

Ramsey

0 takeru ishibashi 4 months ago in reply to Ramsey Foote

Prodigy 90 points

Hi Ramsey

Thank you for your reply.
Is it correct that the register corresponding to the clipper threshold setting is 0x18, and the registers corresponding to the makeup gain setting are 0x1C and 0x20?
Also, what do registers 0x19~0x1B, 0x1D~0x1F, 0x21~0x23 represent?

Regards,

Ishibashi

0 Ramsey Foote 4 months ago in reply to takeru ishibashi

TI__Genius 9175 points

Hi Ishibashi,

Not quite. As mentioned in the document I linked to, these registers correspond to prescale and post scale which can be derived from the makeup gain and clipper threshold. This derivation is explained in the document. Each of these data values are 4 bytes long to they take up 4 registers. This means that register 0x18 is the upper 4 bits of the data stored in registers 0x18, 0x19, 0x1A, and 0x1B. If you used the I2C monitor in PPC3 when setting the clipper, you will be able to see setting of these registers.

Regards,

Ramsey

0 takeru ishibashi 4 months ago in reply to Ramsey Foote

Prodigy 90 points

I understand that the above registers represent pre scale/post scale.
In the document you sent me (TAS58xx Tuning Guide), the pre scale value is 2 when the threshold is -6dB, but how should I calculate this from the register values 0x18~0x1B?

Regards,

Ishibashi

0 Ramsey Foote 4 months ago in reply to takeru ishibashi

TI__Genius 9175 points

Hi Ishibashi,

Register 0x18 is stored in a 9.23 format. This means that for the 32 bits of data (the 4 registers), the MSB is a sign bit, there are 8 bits of data greater than the decimal point, and then 23 bits below the decimal point. Registers 0x 1C and 0x20 are stored as 2.30 data formats. Data formats are explained in the document shared and the TAS5815 Process flows document.

Regards,

Ramsey

0 takeru ishibashi 4 months ago in reply to Ramsey Foote

Prodigy 90 points

Hi Ramsey

I understand how to interpret the bit strings in registers 0x18, 0x1C, and 0x20.

I think 0x18 is the register that determines the pre-scale coefficient value, but what does this value tell us?
For example, if I set the clipper level = -6 dB, how does this value relate to it?

Regards,

Ishibashi

0 Jesse Ji 4 months ago in reply to takeru ishibashi

TI__Mastermind 20041 points

hi Ishibashi

pls using our ppc3 gui to get the corresponding register values. it is more efficient to use.

also, about the tas5815 gui, pls download from below link for temporary using.

the official release need some time for going through application progress.

https://tidrive.ext.ti.com/u/rakvOIOpL1W_qS80/755a129d-e047-4216-bf13-9d867220cc04?l

zK199^FR

tks

jesse

0 takeru ishibashi 4 months ago in reply to Jesse Ji

Prodigy 90 points

Thank you for suggesting checking using the GUI.

However, what we would like to know are the following points that probably cannot be confirmed using the GUI.
・An explanation of each byte that makes up the pre-scale coefficient (0x18~0x1B)
　For example, what do the 8 bits from 0x19 7bit to 0x18 6bit make up?

Regards,

Ishibashi

0 Jesse Ji 4 months ago in reply to takeru ishibashi

TI__Mastermind 20041 points

hi Ishibashi

can you kindly tell me why you need these information?

it seems like GUI already can give enough information about how to use the clipper.

thanks

jesse

0 takeru ishibashi 4 months ago in reply to Jesse Ji

Prodigy 90 points

Hi Jesse

During development, I need to fine-tune the clipper settings, and I would like to know the above information because I would like to reduce the process of having to check the PPC every time I adjust the values.

Currently, it is possible to set the clipper using the GUI, but when adjusting the settings via I2C, I need information such as which byte corresponds to the threshold, what the other bytes represent, and how the coefficient value changes depending on the value of the byte.

Regards,

Ishibashi

0 Jesse Ji 4 months ago in reply to takeru ishibashi

TI__Mastermind 20041 points

hi ishibashi

let me confirm with team how much info can be released to customer.

thanks

jesse

0 takeru ishibashi 4 months ago in reply to Jesse Ji

Prodigy 90 points

Hi Jesse

I understand that you will have the team look into this.
Thank you in advance.
When will we know the results of the review?

Regards,

Ishibashi

0 Jesse Ji 4 months ago in reply to takeru ishibashi

TI__Mastermind 20041 points

hi Ishibashi

i already contacted with team.

but haven't got the reply. i think it should be ok get a reply by this week.

tks

jesse

0 takeru ishibashi 4 months ago in reply to Jesse Ji

Prodigy 90 points

Hi Jesse

Thank you for contacting your team.
I understand that I will receive a reply within this week.
Please respond when you receive the reply.

Regards,

Ishibashi

0 Jesse Ji 4 months ago in reply to takeru ishibashi

TI__Mastermind 20041 points

hi takeru

sure, i will share you the result by Friday.

thanks

jesse

0 Jesse Ji 4 months ago in reply to Jesse Ji

TI__Mastermind 20041 points

hi Ishibashi

let me send you the excel for the calculation by email.

thanks

jesse

0 takeru ishibashi 3 months ago in reply to Jesse Ji

Prodigy 90 points

Hi Jesse

I have just sent you an email asking you to tell us the password to unprotect the file you provided.
Thank you for checking.

Regards,

Ishibashi

0 Jesse Ji 3 months ago in reply to takeru ishibashi

TI__Mastermind 20041 points

hi Ishibashi

let use discuss this by email.

as it need NDA between TI and your company.

thanks

jesse

0 takeru ishibashi 3 months ago in reply to Jesse Ji

Prodigy 90 points

Hi Jesse

Thank you for removing the protection for this file.

I have an additional question:
In how many dB increments can the clipper threshold and MakeupGain values be set?

Regards,

Ishibashi

0 Jesse Ji 3 months ago in reply to takeru ishibashi

TI__Mastermind 20041 points

hi Ishibashi

threshold: -24dB ~ 0dB

makeup Gain: -110 ~ 6dB.

thanks

jesse

0 takeru ishibashi 3 months ago in reply to Jesse Ji

Prodigy 90 points

Hi Jesse

What is the smallest increment for these parameters?
For example, is the next smallest value after threshold=0dB -0.1dB? Or -0.01dB?

Regards,

Ishibashi

0 Jesse Ji 3 months ago in reply to takeru ishibashi

TI__Mastermind 20041 points

hi Ishibashi

0.01dB accuracy is recommended to use.

thanks

jesse

0 takeru ishibashi 3 months ago in reply to Jesse Ji

Prodigy 90 points

Hi Jesse

Understood.
Thank you for your reply.

Regards,

Ishibashi

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TAS5815: How to set the TAS5815 Clipper register