Regarding current consumption

Question

I am using max98303 audio amplifier for one of my project at 5v supply.There will be load of 2 ohm on each output so total 4 ohm of load is at output side.So, my query is how much current it will take from 5V and what will be the total current consumption.(it will be better if calculations is also shown).

MikeNunnery · Answer

When you say that &lsquo;there will be load of 2 ohm on each output so total 4 ohm of load is at output side&rsquo; do you mean that there the speakers (as shown in this diagram) are 2&Omega;? Or do you mean something else? Please provide a diagram to show the arrangements of loads if it is something other than the intended use case shown here. 
 
 Calculating the current consumption of the amplifier requires that you first find the power consumption of the amplifier. Pconsumed = Vsupply * Iconsumed 
 The power consumption is based on the efficiency of the amplifier to deliver power to the load plus the base quiescent power draw of the amplifier. 
 Pconsumed = Pquiescent + Poutput/efficiency 
 From the datasheet: 
 
 So, Pquiescent = 5V * 2.7mA = 13.5mW 
 Peak efficiency in the datasheet is listed as: 
 
 This is the amplifiers&rsquo; ability to turn input power into output power which varies with load. It is based on the resistor divider between the load and the output resistance. Due to this relationship, we can also use this to get a close approximation of the output resistance of the amplifier (RON) which will help us determine power consumption using other loads. 
 In this case, 0.93 = 8/(8 +RON) => RON = 0.6&Omega; Note that is the sum of output resistance for OUTP + OUTN. So, for 4&Omega;, the efficiency would be 4&Omega;/(4&Omega;+0.6&Omega;) = 0.869 
 Based on the above, you should be able to derive the efficiency for any load and, based on your expected output power, derive the input power and input current draw.

MikeNunnery · Answer

If there is no voltage driven on the output, you can see from the above equations that the input current will be only the quiescent current (2.7mA). 
 To really answer your question, we need to know the output signal you are intending to deliver to the load. 
 If you are driving an output voltage, the output current will be VOUT/4&Omega; = IOUT. You should be able to plug into all of the already provided equations above to solve for any of the relevant parameters.

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Regarding current consumption