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TPA6211A1-Q1: Max power dissipation

Andy Snawerdt
Intellectual 1810 points
Part Number: TPA6211A1-Q1
Other Parts Discussed in Thread: TPA6211A1

Hi Team,

My customer is planning to use our TPA6211A1-Q1 to drive a 1W speaker with 8Ω load at Vdd = 5V with max Ta = 85°C . From the spec table, we show the following:

Taking derating into consideration, we land on ~1.11W at Ta = 85°C:

Couple of questions on this:

 1) Why does the Po spec indicate 1.36W typical with an assumed Ta = 25°C, however the dissipation ratings show 1.36W at Ta = 70°C?

 2) I assume the limit to the output power primarily comes down to a thermal limitation of the device, correct? If this is the case, why does the TPA6211T-Q1 have the same Po and dissipation derating specs with a drastically better Rthetaja spec?

 3) What is the max output power for Ta = 85°C? If 1.36W is a typical number, I assume the dissipation rating of 1.11W is also typical. I need to ensure I can at least supply 1W @ 85°C.

Thanks for the clarification!

-Andy

  • 0
    TI__Mastermind 33510 points

    Hi Andy,

    The Power Dissipation table is showing how much power can be internally dissipated before damage occurs. The Output power table is how much power will be retained and be used to drive the load. 1.36W will typically drive the load at 25C with 1% THDN. 1.36W is also how much power can be dissipated before the IC is damaged at 70C ambient temperature. The two quantities are related but the fact they are the same number under different conditions is likely a coincidence. 

    The two devices might have different thermal specs because of different test conditions they were put under. I honestly don't know for certain why they are different considering the schematics and power ratings of the device are identical. If you're concerned about the temperature you can certainly use the TPA6211T. This paper will hopefully help you understand why they might be different: https://www.ti.com/lit/an/spra953c/spra953c.pdf?ts=1646866408398

    There isn't a hard maximum because it depends on how long/continuously you're driving the load, as well as what your actual temperature inside the chip is. Regardless, this device (TPA6211A1) should suit your needs. Table 2 in the data sheet shows that you can drive a 1W 8ohm load with a 5 Vdd supply (1.6W draw) and be within spec for up to 105C. You should have plenty of margin to implement the device under your conditions.