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TAS5822M: TAS5822M no audio output

Michele Iandoli
Prodigy 30 points

Part Number: TAS5822M

Tool/software:

Hello, 

we are working on a prototype consisting of TAS5822M which is configured with a microchip microcontroller.

So far we have configured the class D amplifier with the I2C protocol and we are sending te I2S protocol correctly. We checked the output terminals with an oscilloscope but there is no signal. 

We also tried to connect the same I2C and I2S buses to the TAS5822MEVM and it worked, there is our audio output, that means that the protocols work fine.

We followed the schematic in the datasheet of the TAS5822M, but we missed the connection of the pad (pin39) to the ground. Could that be the problem?

this matter is in great urgency so I look forward to your response.

Kind regards.

  • 0
    TI__Mastermind 20541 points

    hi Michele

    pad has to be connected to GND. otherwise it affects the thermal, also the signal quality.

    but your problem should not be caused by this.

    can you read the register 0x68, 0x70,71,72,73.

    they can tell us what kind of fault might have in amp so that no sound come out.

    thanks

    jesse

  • 0 in reply to Jesse Ji
    Prodigy 30 points

    Hi Jess, thanks for your immediate reply.

    These are the value on the registers when PVDD is 20Volt:

    0x68 -> 0x01

    0x70 -> 0x03

    0x71 -> 0x01

    0x72 -> 0x00

    0x73 -> 0x04

    These are the value on the registers when PVDD is 24Volt:

    0x68 -> 0x01

    0x70 -> 0x02

    0x71 -> 0x01

    0x72 -> 0x00

    0x73 -> 0x04

    We are using hte PBTL mode and this is our schematic.

    The CF1 net (DVDD)  is 3.3 Volt.

    EDIT:

    Pin 29 (PDN) is connected to 3.3 Volt by 10K pull-up.

    kind regards.

  • +1 in reply to Michele Iandoli
    TI__Mastermind 20541 points

    hi Michele

    it is strange, you have so many fault be reported by registers.

    this usually because the amp hasn't really be powered up correctly.

    have you noticed below items:

    1.the power up sequence if fig 7-15.

    2.each power supply voltage.

    thanks

    jesse

  • 0 in reply to Jesse Ji
    Prodigy 30 points

    Hi Jess, thanks for your suggestion.

    We solved the error but still no audio and no signal is coming out from the amplifier.

    These are the value on the registers when PVDD is 12Volt:

    0x68 -> 0x03

    0x70 -> 0x00

    0x71 -> 0x00

    0x72 -> 0x00

    0x73 -> 0x00

    These are the value on the registers when PVDD is 22Volt:

    0x68 -> 0x01

    0x70 -> 0x00

    0x71 -> 0x00

    0x72 -> 0x01

    0x73 -> 0x04

    It means that we have a temperature problem, but it still should play at 12 Volt. 

    Any suggestion?

    kind regards.

    EDIT:

    we tried again at 7 Volt and now it is working, thanks for helping us out.