TAS5431-Q1: Class-D amplifier

Hello Shadow He,

Thank you so much for the quick response.

1.The Max amplified value by internal class-D amplifier will be 4.5Vrms. any how we can limit that value to max. 3V.

2. We will be fine with Resistor setting on PCB  or GPIO configuration from MCU.

3. Yes we need amplifiers for three different channels.

       a) Differential outputs SPKLP, SPKLN or SPKRP, SPKRN ( Loud speaker) from internal Class-D amplifier. Either speaker Left or right we will be using. Not both.

       b) Single ended outputs HPL, HPR(Headphone) from internal Class-H amplifier

we are fine to use separate amplifiers for Headphone and Loudspeaker if not available in single package.

4. The amplified outputs from TI amplifier will be connected to external speaker and Headphone. Can you suggest us a solution for Protection from ESD, TVS and EMI/EMC ? or TI has built in protection?

Thanks and Regards,

Pedaiah G.

Hi Pedaiah

Pedaiah G said:

1.The Max amplified value by internal class-D amplifier will be 4.5Vrms. any how we can limit that value to max. 3V.

  I think the most easy way is to restrain the input signal level. Or you can use another amplifier to reduce the voltage level before send into our Amp.

Pedaiah G said:

2. We will be fine with Resistor setting on PCB  or GPIO configuration from MCU.

I'm really sorry that I checked the Auto side products, they don't support to adjust Gain setting in this way, must use I2C.

Pedaiah G said:

3. Yes we need amplifiers for three different channels.

If you like to use TPA54xx products, as they don't have Line OUT mode to connect headphone, we recommend to add RC series after the filter to ensure the stability. Like below picture. If you choose newer products like TPA6304, you can set one channel as Line OUT mode, that can connect headphone without problem.

Pedaiah G said:

Can you suggest us a solution for Protection from ESD, TVS and EMI/EMC ? or TI has built in protection?

The ESD protection already been built into our product. For EMC, to pass the Auto standard, we'd recommend to use a π filter from PVDD input, put additional10nF cap for every OutP and OutM at the PCB port side. Take care of the LC loop, make it smaller also close to our Amp. Put the output trace at the middle layer of the PCB.

Hi Shadow He,

1. OK Noted. As per your suggestion we will limit the output to 3V and provide as input to TI amplifier.

2. OK Noted. We will change the design such way that gain should be controlled by I2C.

3. We will go with newer product TPA6304 for both Headphone and Loud speaker amplification.

since MAX98090 CODEC Headphone output has Class-H amplifier and Loudspeaker output has class-D amplifier, Any issue in Cascading these outputs with TPA6304 inputs for more amplification? Below is  MAX98090 CODEC Block diagram.

4. OK Noted.

5.Since MAX98090 CODEC Speaker output is Differential and Headphone output is single ended, But TPA6304 input looks single ended and output is differential. Do i need to use Single ended to differential and differential to single ended converters for Interfacing MAX98090 and TPA6304?

Thanks and Regards,

Pedaiah G.

Hi Pedaiah

Pedaiah G said:

Any issue in Cascading these outputs with TPA6304 inputs for more amplification?

Should be no problem about this using, our device is able to filter out the high switching noise. But still suggest you to add a filter after your CODEC output before send the audio into our amp.

Pedaiah G said:

Do i need to use Single ended to differential and differential to single ended converters for Interfacing MAX98090 and TPA6304?

This is one choice, but maybe inconvenient to you. Considering your CODEC output, we can choose TPA6404 device. It's very similar with TPA6304, but with differential input port. Can support both differential and single end input. Please follow below link, and request for detailed datasheet.

https://www.ti.com/product/TPA6404-Q1?keyMatch=6404

Hello Shadow He,

1. OK. Noted.

2. we have requested for TPA6404 Datasheet. Once we receive, we will design and share the design for your review.

    Does TPA6404, also support both Single and differential ended analog output?

3. For TPA6404, Single ended and differential ended input to be configured through software or hardware??

Thanks and Regards,

Pedaiah G.

Hi Pedaiah

Pedaiah G said:

Does TPA6404, also support both Single and differential ended analog output?

Sorry, for our newer designed devices, only support differential output.

Pedaiah G said:

Single ended and differential ended input to be configured through software or hardware?

Only change hardware connection would be fine.

Hello Shadow He,

1. OK, Noted.

   For HPL & HPR channels of  Headphone requires single ended input.

   So,Can we use OUT_1P to HPL and OUT_1M to GND,

                            OUT_2P to HPR and OUT_2M to GND ?

   or Do you suggest to use Differential to Single ended converter?

2. OK, Noted.

Thanks and Regards,

Pedaiah G.

Hello Shadow He,

if my headphone Left and Right channels requires single ended input, How to do i interface headphone to TPA6404 differential outputs?

Thanks and Regards,

Pedaiah G.

Hello Shadow He,

We are using a Headphone, having Single ended Left and Right channels.

Can we use OUT_1P to HP Left and OUT_1M to GND,

                    OUT_2P to HP Right and OUT_2M to GND ?

  if not, can you suggest Differential to Single ended converter for TAS6404 outputs?

Thanks and Regards,

Pedaiah G.

Hi Pedaiah

Pedaiah G said:

Can we use OUT_1P to HP Left and OUT_1M to GND,

                    OUT_2P to HP Right and OUT_2M to GND ?

   Your description is actually the single end using, our device don't support it. I'll double check about the converter.

Hello Shadow He,

Sorry for the delay in response as i was facing issue with TI E2E support forum maintenance issue.

Since Headphone Left and Right channels Output of MAX98090's are single ended, I have used Both TPA6404-Q1 + INA1620 and Implemented the Final required circuit.

Please find the attached circuit and Request your comments. 

we are also open for better solution other than TPA6404-Q1 + INA1620 devices.

AMPLIFIER CIRCUIT.pdf

Thanks and Regards,

Pedaiah G.

Hi Pedaiah,

Shadow is out this week on the National Day holiday in China.  I will respond to your questions and your review your schematic while he is out.  

1. I do not see any coupling capacitors on the audio input piins.  Replace R84, R86, R89 and R90 with 470nF capacitors.  R81, R82, R83, R85 with 470nF capacitors, if you do not have them on the MAX98090 Outputs.
2. The Mute Pin logic is inverted.  Your logic keeps it muted all the time
3. The LC Filter for the outputs that go to the INA1620.  They need to match in the input impedance of the INA1620 circuit
4. Can you bypass the TAS6404 and connect the INA1620 directly to the headphone outputs of the MAX98090?  
5. If bypassed, can you use a TAS5441?
6. Could you use a TI codec or ADC that can meet your needs?

I cannot comment on the INA1620 schematic.  

Regards,
Gregg Scott

Hello Scott,

OK. Thank you for your quick response.

1. OK Noted.

2. OK Noted.

3. As per datasheet, INA1620 has Differential input impedance of (60kohm II 0.8pF) and Common mode input impedance of (500Mohm II 0.9pF) .

   Can you please share any application note or design equation to match the impedance with LC Filter?

4. Since MAX98090 CODEC headphone output left and right channels are single ended, that is why we have connected through TAS6404.

    Can i connect single ended inputs to  INA1620 ?

5. Can i connect single ended inputs to TAS5441 ? if yes, i can use Two devices such for headphone left and right channels.

6. We don't have any provision to change the current design right now i mean we cannot change CODEC MAX98090.

Thanks and Regards,

Pedaiah G.

Hi Pedaiah,

1. noted
2. noted
3. I would use an RC filter instead of a LC filter in this position.
4. I am sure you can connect the INA1620 in a single ended input.  
5. You can easily connect the inputs of a TAS5441 as single ended, Two of these makes good sense, especially on price.
6. Understood

Regards,
Gregg Scott

Hello Gregg Scott,

As per your suggestion, we will implement an amplifier circuit with TAS5441.

Attached the Block diagram of our final requirement.

Audio amplifier Block diagram.pdf

can i connect in the following way??

1) Headphone Left channel - Device 1

IN_P --> HPL 

IN_M --> GND

OUTP --> HPL_OUT

OUTN --> GND

2) Headphone Right channel - Device 2

IN_P --> HPR

IN_M --> GND

OUTP --> HPR_OUT

OUTN --> GND

or Do you suggest any better solution?

Thanks and Regards,

Pedaiah G.

Pedaiash,

You can also use the TAS5441 for the loudspeaker connection.  Basically. you can use three TAS5441 for this circuit.  No need for I2C as this device does not need it unless you want to monitor the faults and warnings.  Also, you do not need a heatsink as the pcb ground plane is used as a heatsink.

Regards,
Gregg Scott

Hello Scott,

OK Noted.

We will use Three TAS5441 for Loudspeaker, Headphone Left and right channels.

Differential output of TAS5441 connected as single ended for Headphone Left and Right channel.

Attached modified block diagram for your reference.

Audio amplifier Block diagram VER1.pdf

is this correct to meet our requirement?? if Yes, we will share the final design for your review.

Thanks and Regards,

Pedaiah G.

Hello Gregg Scott,

Thank you so much for Block diagram review.

Please find the attached Amplifier circuit for Loud speaker, Headphone Right and Left channels using TAS5441.

TAS5441 AMPLIFIER CIRCUIT.pdf

Request your comments on the design and impedance matching with MAX98090 CODEC.

Thanks and Regards,

Pedaiah G.

Hello Gregg Scott,

Thank you for the circuit review.

OK Noted.

Request your feedback on Impedance matching between TAS5441 and MAX98090 CODEC in the attached file.

TAS5441 AMPLIFIER CIRCUIT VER.1.pdf

Thanks and Regards,

Pedaiah G.