LM4670: I need clarification for an audio power amplifier circuit component

Hi Hari,

1. Will the PA I selected w be able to drive this 4 ohm speaker?
   1. Yes, it can.
2. What are the things to be considered when selecting the PA for driving a speaker?
   1. Depends what the system is and the requirements.  Are we looking for efficiency, THD+N, max output power?  How good is the speaker performance to match an appropriate amp to it.
3. How much power will I get at the output?
   1. 
4. In digikey during PA selection I can see that, Max Output Power x Channels @ Load is "3W x 1 @ 4Ohm" May I know what you mean by this?
   1. This means that it's a 1 channel device and under a resistive load of 4 ohms, it can output 3W RMS continuously. 
5. What will happen if I used the PA with above spec to 8 ohm speaker 
   1. You would get better THD+N at the same comparative power level
   2. You would get better efficiency
   3. But, you would 1/2 your max output power

As for you schematic,

1. Input sensitivity.  Make sure you set your gain correctly using R563 and R564 to get your desired max output voltage.

2. These protection diodes look like 5V?  Please make sure that the supply voltage is at least 1V below this threshold.

-Jeff

Hi Hari,

This overview can help you select which part is correct for your application.

https://www.ti.com/audio-ic/amplifiers/speaker-amplifiers/overview.html

-Jeff