• State
  • Locked Locked
  • Replies 8 replies
  • Subscribers 30 subscribers
  • Views 1805 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TPA3221: TPA3221

Markus Friberg
Prodigy 150 points
Part Number: TPA3221

Hi,

I wonder if there are any specific guidelines or recommendations for EMI-filter on the DC-power-supply-input for a design using TPA3221!

In my design I will use 2x TPA3221 and when I look at the EVM schematic there are only 3 caps on the DC-supply inputs! Is this sufficient from an EMC(EMI) point of view?

I will supply my design from an AC/DC adaptor with about 1.5m DC-cable.

Do I need to add for example a common mode choke at the DC-supply-input to my board?

Best regards

Markus

  • 0
    TI__Guru 62730 points
    Markus,

    Let me clarify this with the team and get back to you.

    From my point of view the EVM itself shouldn't have an EMI issue.

    Regards,

    -Adam
  • 0 in reply to Adam Sidelsky
    Prodigy 150 points

    Antipop.pdfHi,

    I have another question regarding the 3221:

    The EVM has a voltage monitor that forces the device in RESET when supply voltage and/or the +15V (mid voltage) goes below a certain threshold level. For example when the power supply is removed (switched off) this circuit prevents click-pop-noise. My design is single supply and therefore I only have 1 single voltage to monitor - PVDD.  How should I connect to the voltage monitor? See my proposal attached!

    Thanks and best regards

    Markus

  • 0 in reply to Markus Friberg
    TI__Guru 62730 points
    Markus,

    Are you planning on using the internal TPA3221 regulator for 5V for VDD/GVDD/AVDD? Will you need any on board pull-ups?

    Regards,

    -Adam
  • 0 in reply to Adam Sidelsky
    Prodigy 150 points
    Hi Adam,

    Yes, I intend to use the internal (on chip) 5V LDO! I also have an external +5V (DC-DC step down 24V-to-5V) and a 3.3V LDO for a DSP available on the same board!

    Regards
    Markus
  • 0 in reply to Markus Friberg
    TI__Guru 62730 points

    Markus,

    That reset circuit works best when the voltages it monitors are the same ones the device uses. For this reason the latest TPA3221EVM (releasing soon) uses the board 5V instead of the 15V on the resistor divider as shown. I would use the same resistor values on your board for this. The goal is to bias that input pin at about 3-4V so we do 1k and 4k for 4/5th of 5V.

    As a reminder, the AVDD output only works while the TPA3221 is powered and out of RESET so pull ups are best powered by an external 5V if you need them up at power up.

    Regards,

    -Adam

  • 0 in reply to Adam Sidelsky
    Prodigy 150 points
    Hi Adam,

    I can use my regulated 5V or 3.3V for pull up!

    But I still dont see the actual transient function of the circuit above! Having PVDD rail dissapearing (dip), given the component values above, does not pull down the node (U7.4) enough to cause a reset. Only when 5V goes down the RESET will kick in. Or do I misunderstand the purpose of the circuit?

    My experience, from f x TDA3118, is that the major POP noise appears when I abruptly switch of the supply (PVDD)!

    Regards
    Markus
  • 0 in reply to Markus Friberg
    Prodigy 150 points
    Hi again,

    Does that also mean that gain/SLV cannot be pulled to AVDD if I use the internal LDO? What about FREQ_ADJ and HEAD?

    Regards
    Markus
  • 0 in reply to Markus Friberg
    TI__Guru 62730 points
    Markus,

    You can use AVDD to pull up the TPA3221 pins, any other pins such as those on other EVM circuits should not rely on AVDD as it is low current only and is OFF when the TPA3221 is in RESET.

    On the EVM we have the option to use AVDD for all the board pull ups but don't do so because we have additional things like LEDs and such that would take too much current and also need to always be on even if the TPA is in RESET.

    Regards,

    -Adam