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TAS5414C: 25 W Stereo into 8 Ohm load

Daniel Potts
Prodigy 110 points
Part Number: TAS5414C
Other Parts Discussed in Thread: TAS5414, TAS6424,

Hi All,

Looking to design a constant power stereo amplifier that can output 25W into 2, 4, and 8 Ohms. The datasheet seems to indicate that the TAS5414 is fine to output 25W into 2 and 4 Ohms, but it doesn't seem to mention 8 Ohms at all (to my knowledge). Let me know if this is impossible or if maybe a different Class D IC is better suited for this application.

Thanks,

Dan

  • 0
    TI__Expert 6295 points

    hello,

        we have new device TAS6424 device which can support 2ohm, 4ohm, 8ohm 25W application.

    Regards

    Linda

  • 0 in reply to Xiaolin Qin
    TI__Mastermind 35865 points

    Daniel,

    Please explain your need for constant power into these loads.  An audio amplifier is constant output voltage, so it if you change the load, without changing the output voltage, the power will change.  P=V^2/R 

    We have many parts that can support your output power and your speaker load needs.  TAS6424, TAS6422, TAS6421 for digital input.  We have the TAS5414C and the TPA6404 for analog input.

  • 0 in reply to Gregg Scott
    Prodigy 110 points

    Hi Gregg,

    Thanks so much for the answer. I actually forgot to specify that it needs analog inputs but you already answered my question! I fully understand that a typical power amp will output higher power into lower impedance loads and would require complex external circuitry to adjust the voltage rails to maintain constant power across differing loads. I'm simply looking for an amplifier that could be used in this type of constant power circuit and is capable of outputting 25W into all three loads mentioned previously (2, 4, and 8 ohm).

    The TAS5414C and TPA6404 both seem promising. I can see that their product pages state that they can output 28W and 27W into 4 Ohms respectively (and can handle 2 Ohm loads as well). What I'm confused on is where in their datasheets you are able to determine their output specs for 8 Ohms (I don't see any mention of 8 Ohms in the datasheets at all). Also, is there a more in depth datasheet for the TPA6404? The one on its product page is a little brief.

    Dan

  • 0 in reply to Daniel Potts
    TI__Mastermind 35865 points

    Hi Dan,

    Basically, if you can drive 4 ohms, you can drive 8 ohms.  For the 8 ohm case you will need to increase the power supply voltage to near its highest allowed value so that you can meet 25W.

    We do not spec 8 ohms as it is not typically used in automotive systems.  These devices are designed for automotive use and therefore, we do not spec for 8 ohms.    

  • 0 in reply to Gregg Scott
    Prodigy 110 points

    Hi Gregg,

    Good to know. Thanks for the prompt replies. This was very helpful!

    Dan