stereo 2X20W streamer with high quality lineout

Hi Jean, 

Welcome to E2E, Thanks for your interest in our products!.

I think that the best part for this could be the TAS5760MD. the gain of the line driver can be modified when the driver is being used as a headphone amplifier, but it can be easily configured so that noise, stability, and input capacitor size are kept within acceptable limits for line applications. 

Best Regards,

  -Diego Meléndez López
   Audio Applications Engineer

Hello Diego,

Thanks for the answer. I agree that TAS5760MD seems interresting. But the problem with this chip is that I don't know how to make the link between the I²S and the Line driver amplifier input.

Do I need a second codec? Or Do I have missed somethnig that allow to route the audio signal to the Line driver?

Regards,

Jean

HI Jean,

Thanks for the feedback, I understand your request. Unfortunately, the line driver of the TAS5760MD does not have a way to select I2S audio of the amplifier as the input source. A codec may be required if you need to stream the same source trough the outputs of the amplifier and line driver. For this, I may recommend the use of a codec of the TLV320AIC310x as the line driver and audio source, and the TAS5760M as the amplifier (same as MD but without line driver). 

Regards,

  -Diego Meléndez López
   Audio Applications Engineer

Hello Diego,

Thanks for the info. Is it possible to connect both TLV320AIC310x and TAS5760M on same I²S bus and have them suing same data?

By the way, what do you think of the idea to pick-up the analog signal of TAS5756M between the DAC and the amplifier to use it as line out?

Best regards,

Jean

Hi, Jean,

Yes, I²S bus can be shared between codec and amplifier. About your second question, the TAS5754 requires the DAC output to be connected to SPK_INxx pins, so using it as a line out is not an option.

 Best Regards,

  -Diego Meléndez López
   Audio Applications Engineer

Hello Diego,

The idea was to use DAC_OUT as Line_out (probably with a small buffer) and as SPK_INxx. If the buffer input is high impedance, it should not degrade the signal received at SPK_INxx?

Regards,

Jean

Hi, Jean,

We have no information of the device being used in the configuration you mention, so we can't guarantee that the amplifier will work correctly if used like that.

Best Regards,

  -Diego Meléndez López
   Audio Applications Engineer

Hello Diego,
I have some new information from our customer and from my colleague from software side.

If we have to add an additional codec, our customer would like that we use PCM1792A or PCM1796A, which are very good and add a real marketing value.

From software, it doesn't seem obvious to tell linux that there are two codec on the same I²s and that it must configure them correctly.
Therefore, we wonder if it would not be easier to have only one PCM1792A on I²S and to split the analog signal between lineout and analog input of class D amplifier (TPA3132D2 for instance)?
What do you think about this?
Which analog buffer circuit do we have to foresee to split the analog signal?
Is TPA3132D2 a good choice or can you advice a more efficient and/or better audio quality to output 2X20W?

Hi Jean,

I think there is a misunderstanding, I2S bus can be shared between several devices, because the data stream is digital Audio. There is no address required for the slave device in I2S protocol, as in the case of I2C where you can have several devices in the bus, but all with different addresses.  

About the application, I think the use of a buffer as you mention won't be required as you can use the I2S bus to provide the audio input for a TAS5760M or TAS5754M (closed-loop, very good audio performance and reduced BOM), and using an DAC (I think PCM5122 may be a good option) as the line driver.

Best Regards,

  -Diego Meléndez López
   Audio Applications Engineer

Hello Diego,

We agree that sending the i²S data to two IC is not a problem. But what we don't understand is how Linux will know how to configure the two chip (through the I²C bus). As far as we understand, Linux will have to tell trough I²C to the two IC how will be the I²S format (bit rate, word size, ...) and chip specific configurarion (P0-R61 for volume control of TAS5754 for instance)

We don't know how to explain to Linux that the "sound device" includes two different codec. Do you have application exemple under Linux of such dual codec implementation?

Best regards,

Jean

Hi, Jean,

I am not very familiar with Linux, but I think the easiest way to get the configuration done will be using a generic I2C read/write tool in Linux, specifying the device address and sending the register writes to configure the devices. Another option may be to use the TAS5760M in HW mode, so you will only need to configure the codec via I2C (or not, if you use it in HW mode as well). 

Best Regards,

  -Diego Meléndez López
   Audio Applications Engineer