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TAS5614LA BTL 3ohm load consideration

user4292685
Intellectual 935 points
Other Parts Discussed in Thread: TAS5614LA, TAS5624A

Hi,

I'm working to drive TAS5614LA as BTL 3ohm and found adding shottky diode (CR1-CR4) on each OUTPUT pins in TAS5614LA EVK's schematic below.

Could you tell me the reason why these shottky diode are needed in case of 3ohm load?

In addition, the document said that ROC should be changed to 22ohm in case of 3ohm load. Please also tell me why.

Thanks, 

  • 0
    TI__Guru* 95335 points
    Hi user4292685,

    These recommendations present in the TAS5614LA user guide were originally made for TAS5612L/14L. Schottky rectifiers are not needed.
    You need to take care of the heat sinking with 3 ohm load operation. If you need better efficiency you can take a look at TAS5624A.

    Best regards,
    Ivan Salazar
    Texas Instruments
  • 0
    TI__Prodigy 475 points
    Hi user4292685,

    I noticed that you included a question about ROC. When you decrease your load to 3 Ohms, you will need more current to drive the speaker to clipping, compared to the 4 Ohm case. To avoid early current limiting, which would limit your maximum power, you will need to decrease ROC to the minimum value. The lower ROC goes, the higher current the TAS5614LA will put out before reaching a current limit. However, if you look at the latest TAS5614LA datasheet, 24K is the minimum allowable value, not 22K. The default ROC value in the TAS5614LA EVM is 30K, which is really best suited for a 6 Ohm load. You can try 24K on your EVM and see if it meets your needs. If you require more current, as suggested by Ivan you could use the TAS5624A which will drive 3 Ohms easily in BTL mode. It is pin compatible with TAS5614LA.
  • 0 in reply to Jeff Berwick
    Intellectual 935 points

    Hi Jeff-san,

    Thank you for your reply.