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TAS2557: how to implement stereo by 2x TAS2557

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Replies: 6

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Part Number: TAS2557

Can customer implement stereo by 2x TAS2557?

For echo reference, both TAS2557 need to output its DOUT1 to SDM636 respectively. It looks Dout needs two I2S, but TAS2557  only one I2S input.

Can you teach me how to implement stereo speaker in TAS2557?  if not, is there any stereo amp supporting stereo speaker?

 

  • Hello, Peter,

    Unfortunately, we don't have stereo low-power amplifiers with digital input, customer would require to use an analog input for a single chip solution.

    However, customer may use two TAS2557 in stereo mode. It is supported in this kind of devices.

    The idea is to use both channels of I2S protocol. By default, the TAS2557 uses the left channel to receive audio data (see ASI_CTRL_1 register for details). So, the second TAS2557 must be configured to use the right channel. For more details, he may take a look at section 9.4.3 of datasheet:  http://www.ti.com/lit/ds/symlink/tas2557.pdf#page=35.

    In addition, if customer is looking to have a different registers configuration in both amplifiers, he may use ADR0_SCLK and ADR1_MISO pins to set different I2C addresses for both devices.

    I hope to have been clear. Please let me know if you have additional questions or comments.

    Have a good day!

    Best regards,
    Luis Fernando Rodríguez S.

  • In reply to Luis Fernando Rodríguez S.:

    Hello Luis Fernando
    3 more questions from customer.
    1) looks that 2 tas2557 will have a common DIN1 signal that could be shorted together :
    => So it means that it didn’t need to connect to CPU I2S output pin ? No any signal output to smart PA for playback?
    2) if separate DOUT1 signals that have to have independent Pins on the AP. From the AP perspective will be just 1 I2S channel with two DIN pins.
    => does it need Two output to CPU I2S input?
    3) Could you mention in detail and Using TDM, or I2S?
  • In reply to Peter Chen(ICP_FAE):

    Hi, Peter,

    Please take a look at my answers below and let me know if you have additional questions or comments.

    1) looks that 2 tas2557 will have a common DIN1 signal that could be shorted together :
    => So it means that it didn’t need to connect to CPU I2S output pin ? No any signal output to smart PA for playback?

    DOUT pin is used when the Smart Amp feature is required. DOUT sends all the information about the speaker characteristics such current and voltage. If this feature is not required, then DOUT won't be needed to be connected to an external processor. However, if customer requires this feature for signal processing and to optimize output signal, then he would need to connect the DOUT pins together in TDM mode.

    2) if separate DOUT1 signals that have to have independent Pins on the AP. From the AP perspective will be just 1 I2S channel with two DIN pins. 
    => does it need Two output to CPU I2S input?

    Normally, the APs have the capability to interpret multiple channels from one serial interface. Customer has the choice to route an entire serial interface (BCLK, WCLK, DOUT, DIN) per device or, if both devices share the same clock lines, DOUT and DIN pins may be routed together in TDM mode. The AP would be capable to take the data from both devices.

    3) Could you mention in detail and Using TDM, or I2S?

    I2S is an audio protocol that requires a WCLK that separates the channels to be sent, a BCLK that send each data bit per channel and DOUT/DIN lines for data transmission. This protocol is limited to be used per device, sending/receiving data for audio conversion.

    TDM mode is a capability of send data from multiple devices sharing the clock and data lines. TDM mode places the data lines in high-impedance mode when no valid data is sent. This avoid any collision in the data lines that may affect the communication.

    Best regards,
    Luis Fernando Rodríguez S.

  • In reply to Luis Fernando Rodríguez S.:

    Hello Luis Fernando
    Thanks for replying and 2 more questions

    1) So both Din of two smart amps should connected together and connected to I2S output from CPU. -> this is for stereo playback.

    2) We will use Dout from smart amp to CPU for echo reference, because we have two smart amp, could we need two I2S input from CPU?Or Could we use one I2S input from CPU since they are in the same clock?
  • In reply to Peter Chen(ICP_FAE):

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  • In reply to Peter Chen(ICP_FAE):

    Hi, Peter,

    1) So both Din of two smart amps should connected together and connected to I2S output from CPU. -> this is for stereo playback.

    That's right. Both DIN pins can be connected together to the I2S output from CPU. Customer only must ensure that the data being sent from one device doesn't generate a collision with the data of the second device. He may separate the first device data in left channel and the second device data in the right channel, respecting the I2S protocol.

    2) We will use Dout from smart amp to CPU for echo reference, because we have two smart amp, could we need two I2S input from CPU?Or Could we use one I2S input from CPU since they are in the same clock?

    If the CPU supports TDM mode, you may also send all the data to one I2S input. Otherwise, you would need of two I2S inputs from CPU.

    Best regards,
    Luis Fernando Rodríguez S.

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